Vorshlag Motorsports Forum

Vorshlag Motorsports Forum (http://www.vorshlag.com/forums/index.php)
-   Vorshlag Project Cars (http://www.vorshlag.com/forums/forumdisplay.php?f=39)
-   -   Vorshlag Budget TT Build: Project DANGER ZONE (http://www.vorshlag.com/forums/showthread.php?t=8341)

Fair! 12-19-2014 07:28 PM

Vorshlag Budget TT Build: Project DANGER ZONE
Project Introduction, Dec 19th, 2014: Welcome to Vorshlag's latest crazy project build thread. Many of you know how we have documented our various project builds on the forums over the past 12 years and this will be another fun one. I will (soon) be cross-posting this on a number of forums, listed below. Pick your favorite, subscribe, and feel free to join in the conversation! If you've never seen my build threads before, there are links buried throughout (usually in bold) as well as LOTS of pictures. Click on any picture posted and it usually goes to a larger resolution version. I will embed videos in here, too.
Before we get started I have to admit that this is just an introductory, background laying TEASER post. In it I will describe in basic terms what we are doing, and why, but we ARE NOT revealing what this new TT build car is until AFTER our first time trial competition event (NASA at MSR Houston Jan 17-18, 2015). Why? Everyone likes surprises, and I want to spring this on our competitors before they pitch a fit and leave the class, hehehe! This car will be built to run in a NASA Time Trial "letter class" (something from TTB to TTF) as well as SCCA Club Trials (when the two clubs' events don't overlap!). We might sneak it into a few other series and classes, if it looks like a good fit.

Who Are These Vorshlag Guys?


Some of you know Vorshlag (primarily a suspension parts manufacturing and supply company + street/competition prep shop) from our various online build threads, like our 2011 Mustang GT, shown above. We purchased this "test mule" to use for parts development, and with it we tested with 3 brands of shocks (AST, Moton and MCS), all with custom valving. We developed our second revision of the S197 camber plate set-up, helped Whiteline develop and test lots of parts, developed an 18x10" D-Force wheel for the S197 chassis, and tested and race proved Forgestar wheels, among other items.

We tested these things by campaigning it in various racing groups over the past past 4 years (GTA, SCCA, NASA, USCA, Optima, Goodguys) and it was extremely competitive in the last 2 seasons in NASA's TT3 class, with dozens of wins and setting 13 NASA class track records. We also won with this car in Optima/USCA, SCCA Club Trials, Goodguys autocrossing, and more. All of the development on this car has been shared on this Project Build Thread, but that car is currently for sale (here) and off limits to me on a race track from now on. We kind of went overboard on the custom fabrication and suspension work with that build, so somebody is going to get a smokin' deal when they buy it.

This Mustang was an example of Winning at All Costs. We used the best (and most expensive) suspension, high end aero parts, lots of custom body mods, and we ran on brand new "sticker" sets of Hoosier A6 tires ($1700 worth per weekend) at each event to guarantee success. Maybe we over did it... we set every TT3 track record for 2 years on the NASA Texas calendar and in 2014 had win margins over 2nd place by 5-7 seconds on most race days. Overkill costs extra. This DANGER ZONE project will be more about Winning with Low Costs, spending just enough to get that win, without massive overkill modifications or needless expenses. The inherent nature of the TT lettered classes limits our ability to go hog wild with spending or mods, too.

http://vorshlag.smugmug.com/Projects...422281_o-S.jpg http://vorshlag.smugmug.com/Projects..._3898-X2-S.jpg
Our TT3 Mustang was a big brawler - we ran it HEAVY, with the biggest tires Hoosier made, and with huge aero

We learned a lot of valuable lessons with the TT3 build, with breakthroughs and mistakes, and shared them all publicly. While we had generally excellent results the last 2 years, the first 2 years of competition were a bust (poor planning on my part put it into the wrong series & wrong class), and even in 2014 I made a critical error that caused a high speed off. That little shunt at Road Atlanta caused some injuries to my back, but barely hurt the car or the splitter - this car is a tank! I am not keen to repeat those mistakes - so we will use all test data we can get and over-do the safety aspects on this car (spending far more on safety upgrades than are required in Time Trial - so I'm not counting that in the "race prep" budget). That TT3 car progressed greatly the last 2 years, winning 13 of 15 NASA TT events in 2013 and all of the TT events we entered in 2014, while securing the Regional TT3 championships both years by huge margins (with the maximum possible 800 class points). We relearned the importance of tires (width and compound) in TT, the value of proper testing, where to spend money on suspension, and of course we played with a lot of aero.

At Vorshlag, when we purchase "shop car" it is to develop new parts + to go prove those parts in competition. We usually only keep a car for one or two years, jumping around from different makes and models that have ranged from BMWs, Mitsubishis, Subarus, Mazdas, Chevys, Fords and more. Running the same red Mustang four seasons in a row has somehow made us into a "Mustang shop" in many people's eyes. But Vorshlag is much more than that - we make suspension products for over 24 different makes/models and prepare and build race-oriented cars for many motorsports venues, including autocross, HPDE, TT, Club Racing, Pikes Peak, drag race, rallycross, and even top speed competitions.

http://vorshlag.smugmug.com/Customer...B61G1869-S.jpg http://vorshlag.smugmug.com/Vorshlag...492641_o-S.jpg
This pair of Subarus we have worked on aren't track cars. Left one is made for running Bonneville, the other for Pikes Peak

We hope this new build will show some of the variety of cars we work on, across all budgets, and show off some of the fabrication and race prep skills our crew excels at. Of course we are known for LS1 swaps into BMWs (E30, E36, E46, Z3 - see below) and we have Alpha Builds (development projects for future kits) for the Miata NB chassis and Scion FR-S/Subaru BRZ as well. We have sold over 120 V8 swap kits since 2007 and we keep picking up new platforms to add big aluminum V8s to. Sadly, project DANGER ZONE won't be getting LS1 V8 powered swap, but it will make good power for it's class.

http://vorshlag.smugmug.com/Projects...%20final-S.jpg http://vorshlag.smugmug.com/Projects...%20final-S.jpg

A lot of people that see us at the track or read our build thread think "These Vorshlag guys spend a lot of money!", but the reality is we build our cars to run on a tighter budget than you might think. How did we stay on sticker sets of Hoosier A6s in 2013 and 2014? We won all of them, except for 1 set purchased at the beginning of the 2013 season. Our service shop also has experienced mechanics and fabricators who do all of the work on our cars between paying customer work - so we have the manpower, tools and skills, but not always the big bags of cash. We kept the engine bone stock on our TT3 car because it was easier for us to do suspension and aero mods than "purchasing horsepower" (we don't build or tune motors here). We also have two guys in the front office that are crew chiefs on outside race teams, and everyone that works here is a racer with regular motorsports experience, track side and/or behind the wheel. So a lot of times we build the things that might seem "expensive" to others, but are really just hand built items that come from hard work and experience - which can often be worth more than just throwing money at a race car.


We have done some very low budget builds, too. In late 2009 we wanted to try our hand at a budget-restricted magazine shootout, so we jumped into the Grassroots Motorsports sponsored $20XX Challenge. This is an annual 2-day competition event with 3 differing categories: autocross, drag race, and concours. You have roughly two grand to spend on the car and parts, plus a rigid set of rules to go by. With an all-volunteer crew (15 people helped put in 1200+ man hours!) we built a BMW E30 in my home garage with a truck LS-series V8 and ran it in the the GRM $2010 Challenge (as in: we spent less than $2010). We did fairly well that first year, learned a LOT by going to that event, recognized what mattered most by watching the winners, and came back in 2011 and won the whole thing. Lots of people fell in love with that car - whether it was the home built wide body, the nasty little V8 under hood, the BMW Art Car inspired graphics for 2011, or the extensive custom fabrication work done throughout the car to keep the parts budget low.

http://vorshlag.smugmug.com/Projects...DSC_8417-S.jpg http://vorshlag.smugmug.com/Projects...DSC_8298-S.jpg

I also ran our little GRM E30 in NASA TTU class (where it fit with the power to weight ratio it ended up with) and had a blast there as well. It was actually a better track car than an autocross car, funny enough. We cleaned it up, added a splitter, added some good looking 18x11" CCW wheels and sold that car for $18 grand... so sometimes your budget builds DO pay off after all!


Our very first NASA TT car was the TTU BMW E36 LS1 shown above, and it set an overall TT track record in its debut event way back in 2008. After that car left our stable we had a couple of other autocross cars that we ran briefly in TT lettered classes as well. My blue 2001 BMW E46 330 coupe (below left) was built initially around SCCA's DSP autocross class, flared with big 285s under all four corners, but it proved to be a MUCH better track car in TTD. It was run exactly one time and set a TTD record in the process. Same went for our STU autocross prepped 1997 BMW M3, which set a TTC record in one outing without any considerations made for track use.

http://vorshlag.smugmug.com/Projects...copy%203-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5536-S.jpg
These two Bimmers were initially built as SCCA autocross cars but ran briefly - and won - in NASA TT lettered classes

Before This Our 2015 Race Season Looked... Bleak!

After the last two successful seasons running our Mustang in NASA TT3 and a couple of other series, this car was tidied up for SEMA with new flares, new paint, and new aero. We ran it at the Optima Challenge after SEMA as well, then when we came back home in November mid it went up for sale. The car looks so perfect right now that nobody here will let me take it out on track. They think I'll bang up the bodywork or paint... and with as wild as I drive, they are probably right. ;) It now sits to await its new buyer, untouched and undriven.

http://vorshlag.smugmug.com/photos/i...-qLMGZQ5-S.jpg http://vorshlag.smugmug.com/Racing-E...B61G0646-S.jpg
A major shop upgrade + new machines and equipment + extended SEMA/Optima trip all cost a lot of money

We just moved into a new shop that is twice as big as our old place, and did construction here for 6 weeks before we moved. The move happened 2 days before we went to SEMA, which was a 10 day trip for almost everyone here at Vorshlag. The pair of CNC machines arrived a month later. So needless to say, a lot of money was spent on the pre-SEMA car work, the move, construction and equipment of late. My "its a done deal" buyer for the Mustang fell through right before SEMA, too. All of that combined put a series dent in my personal 2015 racing budget!

http://vorshlag.smugmug.com/Projects..._DSC7555-S.jpg http://vorshlag.smugmug.com/Projects...DSC_6713-S.jpg

There's a whole program of cars I was hoping to kick off with a shop built BMW E46 with a BIG nasty LS1 motor planned, and I've got 3 more chassis sitting in my home shop along with this E46, awaiting this turn-key race car program to start. But getting the drivetrain parts and wheels alone is going to take about $20K in cash, which seems to be missing at the moment, heh. So this project is delayed a bit while we get our CNC machines up and running and finish the construction at the new shop, so that meant no Vorshlag team car would be on track for at least 6 months. Sucks.

In Texas we race dang near year round. We did some track testing with the new S550 Mustang as recently as this December and there are NASA and SCCA road course events we need to hit in January and February, so there's no "off season" to complete any big build. Even if we kicked off the E46 build TODAY it wouldn't be on track until May or June. That's the majority of our Texas race season, and NASA Nationals West is in August. Long story short: We're out of time, and need to make a quick, low budget race car to be able to make the 2015 NASA race season.

continued below

Fair! 12-19-2014 07:29 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

Well as luck would have it, something came up and I am picking up a semi-finished race car this weekend. Until we fix a few things, and do a track test, I'm keeping "identities withheld to protect the innocent", so the make and model of the car are under wraps. It will be prepped and stored off site in a secret skunkworks facility...

NASA Time Trial Classing - A Brief Summary

This next bit might be confusing, but I'll be quick. So NASA Time Trial series rules are nearly identical to the Super Touring (ST) wheel to wheel club racing ruleset, without a lot of the safety requirements. Those two series' subsets of classes have a lot of common competition rules but with two distinctly different main philosophies. The "Lettered Classes" (TTB/TTC/TTD/TTE/TTF) are set-up where every car model gets assigned a "base class" then you get 19 points per class to use for "mods", which could be added tire width, aftermarket springs, aero tricks, various tire compounds have differing points values, motor upgrades, etc. If you modify the car beyond your allocated 19 points the car bumps up a class (like from TTD to TTC), and you get another 19 points to use in that class.

NASA Time Trial Rules: http://www.nasa-tt.com/rules

We bought the Vorshlag shop TTB, TTE and TTU cars to a NASA event once and ran them all. That was a hectic day...

These classes also each have their own minimum weight to power ratio that you cannot exceed even if your points expenditure is on lowering weight or horsepower additions, and each base classing includes a "base weight" you start with. If you want to run lighter than the base weight, it costs you points. If you want to run more tire than the base class tire, points. Some base classing also come with either a 7 or 14 point penalty, too (one star or two stars).

Each competition letter class has an assigned a minimum “Adjusted Weight/Power Ratio”. Regardless of how many points a car has, or which base class it begins in, it may not exceed the minimum “Adjusted Weight/Power Ratio” for its competition class. We will have to play with weights or power levels to stick with the limit for the class we're choosing, which could be one of the following:
  • TTB 10.50:1 (10.5 pounds per dyno measured wheel horsepower)
  • TTC 12.00:1
  • TTD 14.25:1
  • TTE 16.50:1
  • TTF 19.50:1
Each letter class is also has an assigned "base tire width", regardless of what the OEM tire is. That list is below, as is small sample of typical base class listings.

TTB: 265mm, TTC: 255mm, TTD: 245mm, TTE: 235mm, TTF: 215mm, TTG: 195mm, TTH: 175mm
  • BMW 330 ('01-'06) (factory 225hp models)... base class TTE... minimum weight 3285 lbs... Base tire is 235mm, power to weight limit is 16.5:1. You have 19 to play with before bumping up a class and could dyno a maximum 199 whp at the minimum weight shown (with driver).
  • Ford Mustang GT ('05-'06)... base class TTD**... minimum weight 3450 lbs... Base tire 245mm. power to weight limit is 14.25:1. Two stars (-14 penalty) means you only have 5 points to play with before bumping up a class and could dyno a maximum 242 whp running at the minimum weight shown (with driver).
  • Mazda RX-8 (R3 model) ('09-'11) ... base class TTC... minimum weight 3045 lbs... Base tire 255mm, power to weight limit is 12:1. You have 19 to play with before bumping up a class and could dyno a maximum 253 whp at the minimum weight shown (with driver).

http://vorshlag.smugmug.com/Racing-E...DSC_1395-S.jpg http://vorshlag.smugmug.com/Racing-E...DSC_1476-S.jpg

The inherently faster and less rules encumbered "Numbered classes" (TT1/TT2/TT3) are different and modifications are almost completely "free" and your power to weight ratio is what matters. Some cars are so fast in stock form they get a base classing in TT1/2/3. There are "modifiers" to that ratio if you run non-DOT racing slicks, sequential transmissions, AWD, and other major parts or changes like that. TT3 is unique in that any non-base trim level OEM aero mods cost you a big 0.5 modifier on your power to weight (we took that in our Mustang build, for example), but aero mods are free in TT1 and TT2. TTU is the "Unlimited" class for NASA TT as well - you can run it as light and as powerful as you want, so long as it meets safety rules and has bodywork over the wheels (NASA eschews all open wheeled race cars).

That was a brief summary only, and I hope that made sense. We wrote this basic primer on NASA TT back in 2008, and of course the TT rules are linked above.

http://vorshlag.smugmug.com/Projects...B61G9401-S.jpg http://vorshlag.smugmug.com/Projects..._DSF3727-S.jpg
We like making track cars fly - using non-stock aero tricks helps in Numbered Classes, but costs "lots of points" in Lettered Classes

We weighed the options for our TT3 and took the aero penalty (running a massive wing out back and splitter/ducted hood up front), maxed out the power to weight ratio (running at 3802 pounds to keep power at 433 whp peak, off of an adjusted 8.8:1 pounds per horsepower ratio), and ran the biggest, stickiest tires made by Hoosier (335F/345R Hoosier A6). On that car we realized early on that the softer tire allowed us to get our fastest lap in the first two laps, before the front of the field tends to catch the back markers, which usually ensured a traffic free lap. That matters. We also noted the wider we went on tires (we started at 265, then went to 275, 305, 315, 335 and 345) the faster the car got. The added areo helped the car in high speed corners, of course, but also seemed to make braking better as well. We hope to apply some of this experience on our new TT car here, which is almost old enough to qualify as a vintage car, but spend less than 1/10th the budget. Will it work?? Are we delusional or genius?? You shall soon see...

Maximum Effect from Minimal Investment

This time we're not starting with a $40,000 brand new car, we're starting with an aging a 24 year old... well.... beater. This car was purchased by the previous owner for $3000, and then he sold the interior bits and some other discarded parts and recouped $1000 of that, so it was s cheap starting point. He then semi-prepped it for TT use but got busy with other projects and he suddenly wanted it gone - so it will soon came to my home shop to knock out the repairs and finish race preparations.

It happens to be "base classed" particularly well, and once people who know TT classes see where it ends up they might cry foul - but is has been classed there for many years and I've been waiting for someone to build one. We will document all of modifications we do openly, show all testing performed looking for every ounce of speed, and post any race wins or losses along the way. Like we tend to do with all of our builds, we will be pouring over the rules looking for the optimum modifications allowed, and with several 25+ year veterans of amateur and pro racing working at Vorshlag, we know how read rules and seek out the most advantages possible.

"Rulebook Research" and bench racing is all part of the fun of building a new race car, for us, and we've probably spent over 25 hours so far just looking at the "free" mods. We have run countless permutations allocating every point in the class (it isn't going to jump up a class), and going over every tire width/compound option, but there are still many unknowns in this build. Will an aero trick worth two points be worth more than a cat-back exhaust? We'll test that. What about this +10 point compound narrow tire vs a much wider +2 point tire? Testing it. Can it meet the power-to-weight limit? We'll dyno test the car early and often through the build.

http://vorshlag.smugmug.com/Projects...B61G2027-S.jpg http://vorshlag.smugmug.com/Projects...DSC_6070-S.jpg

Of course it wouldn't be a Vorshlag build without digital scale pics; we will weigh EVERYTHING we touch. A lot of the interior has already been removed (its 400 pounds under the "base weight", so it will be getting some serious ballast added along with my 200 pound body) and nearly 50 pounds of drivetrain mass has been removed (100% legally), so the bone stock OEM motor is pretty "peppy". Look forward to lots of tech in this build thread which you might enjoy reading - or enjoy applying to your own track build.

If You're Not First You're Last

That Ricky Bobby logic above is going to apply here. As with our most recent TT build, pushing the limits but keeping it 100% legal is our goal for this project, so we won't be satisfied with anything other than a dominant performance and squeaky clean results in after-race inspections. We want to set ALL of the track records, win ALL of the trophies, get ALL of the points, and take home ALL of the contingency tires ... we basically want to swoop into a class we've not run before, act like a school yard bully and take all of their lunch money! :D

http://vorshlag.smugmug.com/Customer...B61G2460-S.jpg http://vorshlag.smugmug.com/Projects...B61G5247-S.jpg
We will be adding a roll cage and fire system, but that's not going to be shown as part of the TT "race prep budget"

Total build budget for this build for the 2015 season we are shooting for is $7500, all-in with initial purchase price + parts. That's not a lot of money for what we think we can pull off with this car, and what we predict the lap times will be (shooting for 6-8 seconds a lap slower than our TT3 records). We will continually be upgrading the car all season, as shop time and budget permits, and it will have proper safety gear (full cage, fire system, nets) very quickly. Who knows - it might even become legal for the mating ST class?

Tune in next time to see if we managed to win our first TT race or failed in epic fashion - either way, it will be entertaining! I will go back after the January NASA race coverage and show the initial 4 week build-up, any pre-race testing, and all of that. I also reserve the right to delete this thread and disavow all knowledge of it if the results are dismal. :P

What's Next + Vorshlag 2015 Race Schedule

These are the Time Trial and other competition events we want to enter with this car in 2015:
  • January 17-18 - NASA @ MSR-Houston Clockwise
  • January 17-18 - SCCA Club Trials @ MSR-Cresson (GRR! Why do they book the same weekends!?!)
  • February 14-15 - SCCA Club Trials @ TWS
  • March 14-15 - NASA @ MSR-Cresson
  • March 22 - Goodguys AAS at TMS (200 treadwear)
  • March 28-29 - USCA @ TMS (200 treadwear)
  • April 25-26 - NASA @ TWS
  • June 13-14 - NASA @ Hallett Summer Shootout
  • July 31-Aug 2 - NASA @ Laguna Seca - Western States Championships
  • September 4-6 - NASA @ VIR - Eastern States Championships
  • September 26-27 - NASA @ MSR-Houston Counter-Clockwise
  • October 17-18 - NASA @ "TBA" (???)
  • November - NASA @ "TBA" (probably ECR)

The main goal is to hit all of the NASA Texas events, and while the Laguna Seca "NASA Nationals West" event isn't that likely for us, "NASA Nationals East" at VIR might be in the cards. Right now we have only FOUR weeks until our first NASA race (we will skip SCCA for NASA, you double-booking dingbats), so its going to be a thrash to get it prepped for track use in less than 30 days! Our shop is very booked with suspension and race prep work, so I will work on it after hours if need be to get it done. Sleep is for the dead!

http://vorshlag.smugmug.com/Projects...B61G9085-S.jpg http://vorshlag.smugmug.com/Projects...B61G9181-S.jpg
Our fab shop just took this street car and turned it into an ST3 prepped race car - cage, wiring, fire systems, aero - in 6 weeks

This is going to a gutted/stripped car with NO compromises for street use at all, which we believe gives us the best chance for success. Daily driven cars haven't won many (any?) TT national championships with NASA in a while. This car has some great prep by the previous owner but it still needs some basic upgrades before it is fully track ready. We need to swap out the radiator for a racing-duty version, add an oil cooler, build in some major front brake ducting, install a proper racing seat (have one sitting in the lobby that I will steal), bolt in some harnesses and wrap them around a 4-point roll bar (initially; cage will be done hopefully by the February event). It also needs tires, a new windshield and a few other small repairs. Again, this is a CHEAP car to start with but when we're done its going to be embarrassingly quick on track. Cheap and Quick!

My final reason for building and racing this car in 2015 is - I'm a degenerate racing junkie, and I was clawing my eyes out thinking I was going to miss the next race season. Sure, I'm bummed that we cannot have the TT1 car built in time to run with NASA this year, so this was my only possible racing option. But I figured that running in a quarter century old beater has to be more fun than NOT racing anything at all, right?

What's in a Name?

We're going to be focusing exclusively on The Things That Matter, so there will be very little time spent on cosmetic improvements or other frivolous upgrades. But of course we do have a vinyl plotter, and a big part of running this car is MARKETING for Vorshlag, so we will throw some simple graphics on the car based loosely on the Martini stripes on the Porsche 918 shown below (substituted with Vorshlag's Red/Black/Silver colors). We're trying to show that we can make anything fast and win, even aging 1980s era cars that have been mostly forgotten.

http://vorshlag.smugmug.com/photos/i...-kw2fJ7s-M.jpg http://vorshlag.smugmug.com/photos/i...-9XTrvv8-S.jpg
“Something, something, danger zone! I know. I’m not even trying anymore.” - Sterling Archer

We've come up with a project name (gotta call it something other than "Broke Ass, Last Minute Backup Racing Plan") which has some obscure references to the 1980s, when this particular car was designed. After about 3 minutes of brainstorming we picked Project (DANGER ZONE), which might make more sense when we get this thing on track (there is usually an inherent "Zone of Danger" surrounding me on track, especially in nearby grass areas). We tossed around some ideas to get there, like: the fact that this car designed in the 1980s, it may or may not have been on a cheesy 80's detective show called Miami Vice, which led us to the cars featured in Grand Theft:Auto Vice City, which inevitably led us to the last season of ARCHER season 5: Vice. That's only one missing step to tie into Kevin Bacon, I think. And who doesn't like Archer? Think of all the quotes I can use in my write-ups! This car would fit in well that TV series, if we added an in-dash mini-bar.

...and THAT'S how you get ants...

Other than those obscure hints, I'm keeping my lips sealed. The car will be built at a "secret location" (Dick Cheney's basement), so no matter what you think see in the Vorshlag shop, I won't reveal this dirty little secret until after Jan 17th. I will be posting more clues on the Vorshlag Facebook page, so keep an eye out there.

Until next time,

twoquack 12-25-2014 11:51 AM

Re: Vorshlag Budget TT Build: Project DANGER ZONE

Fair! 12-29-2014 04:40 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for December 29th, 2014: This is an unexpected update - I'm going to break "radio silence" early because too many of you have guessed the car we are building before it's first race. Many of the guesses were hilarious and infinitely entertaining, and some of them were pretty good ideas for TT builds. More importantly this little project got some engagement and feedback. I'm always looking for feedback and comments, in case you have a better idea or way to do something, so keep it up! Now let's get to the answers to "The What and the Why" in this update.

Lucky guesses and True Detectives

Here were the initial clues I put in the first post, then some follow up clues on social media and various replies to questions and guesses on the forums. The clues became more specific as more folks chimed in with better ideas and guesses. If they gave their reasoning in their replies I would often answer yes or no, which led to more clues over the past few weeks.
  • It's not a Mustang
  • It's nearly 25 years old (so roughly a 1991 or 1992 model)
  • It's a chassis designed in the 1980s + something related to Miami Vice?
  • It does not have an LSx V8 in it, but it will be run with the factory installed engine
  • Worth about $3000 nowadays (in poor condition!), when purchased right
  • Not a turbo nor a 4 cylinder, and definitely not Front Wheel Drive
  • I stated that we would be racing on a tire 30mm smaller than the OEM size
  • I drove through Madisonville, Texas on the way to pick up the car from Dallas (hence a lot of guesses that it was in Houston)
  • After picking the car up I said it had a flywheel/clutch 50 pounds lighter than stock, and spun the tires through the 1st three gears
  • I hinted that I had possibly owned one of these cars before, and towards the end I said it was domestically produced
  • Lastly I said I worked "under the bonnet" one day last week, but then admitted not everyone calls it that but it was "more than just a hood"

All of these things were 100% true. The "Danger Zone" name was the only red herring, heh. That last clue was what triggered an avalanche of correct guesses. Jason Newman was the first to guess correctly - and he knew he was right a week before anyone else - with only about half the clues. That guess gets him a free Vorshlag T-shirt! Several others guessed "C4" along the way as well.

My Past Was Also A Hint

It helped that Jason knew more about me than most - he was a racing friend from college, when I raced in and helped run the largest collegiate sports car club in the country, the Texas A&M Sports Car Club. This was a club with over 150 members when I was there and we had one of the best autocross sites in the country - an old air force base that the school owned (Riverside Annex).

http://vorshlag.smugmug.com/Customer...verster1-S.jpg http://vorshlag.smugmug.com/Customer...S/Cam001-S.jpg
Left: My 1994 LT1 6-spd Corvette Z07. Right: One of three V8 1992 Camaro 1LE/B4Cs (ex-pursuit) I owned

We set up huge autocrosess there, joining multiple runways at times. We also had lots of fun at nearby Texas World Speedway (TWS) running annual time trial events we called Aggiecross. This little college club was holding Time Trials back in the late 1980s, which didn't happen in NASA for decades. A lot of us worked at TWS while we were in school, and when we worked corners for PCA HPDE events we got free track time in our clunky, broke-ass student cars as well.

http://vorshlag.smugmug.com/Customer...S/Mus009-S.jpg http://vorshlag.smugmug.com/Customer...Mustang2-S.jpg
Left: My ex-pursuit 1987 Mustang LX 5.0 was one of 6 Foxes I've owned. Right: Amy's 92 Mustang GT and my 1969 Mustang (C Prepared)

During my time racing with TAMSCC, both during college and after, I ran in a variety of cars. Since I was the proverbial "starving student" while in school many of these cars were crappy and cheap, but most of them still V8 powered and RWD. When I met Amy she had an 86 RX7 but once she raced in some of my cars she jumped to Mustangs and then Firebirds. Between us we've owned about 16 pony cars (Camaros and Mustangs) of various years, from 1969 through 2013 models. Two years after graduating I landed my second post-college job, which allowed me to commute from the same town (College Station). I was making great money in an oil field mechanical engineering position, and had extremely low living expenses. At one point there I owned 7 cars, including two project builds and an immaculate two year old Corvette (the white 1994 shown above).

http://vorshlag.smugmug.com/Customer.../S/f4001-S.jpg http://vorshlag.smugmug.com/Customer...8Formula-S.jpg
Left: Amy's supercharged 1994 Trans Am on 17x11" HREs. Right: Her 1998 LS1 Formula

I tell you this because knowing what I used to own and race in my "Pre-Vorshlag Days" (nowadays I typically do NOT buy the cars I want but instead buy cars that need suspension development) helped clue in some old friends that knew this was to be a LOW budget build, but that somehow I knew it would be fast. Three amigos of mine were the ones to ferreted out the last few clues and got to the correct answer without question, before I confirmed it to them privately. These guys knew me too well, and were more racers from my days running with the TAMSCC: Matt Miller, John Scheier, and Doug Willie

Yet nobody correctly guessed that we'd keep it in TTC class.

Project Danger Zone Is...

So get on with the answer already! Sheesh...

This is the car we're building. It looks great, from this angle. This photo was staged perfectly - its a mess from any other angle!

This is it. What you are looking at is a 1992 Chevrolet Corvette 6-speed that is bone stock, except for being stripped of a nasty old interior. This is a base trim level car with the factory 5.7L "LT1" (Gen II) 300 hp iron block V8 and ZF S6-40 6-speed manual transmission. It has the strong Dana 44 rear axle assembly (not the Dana 36 that came in the early C4s and automatics). This particular car has 68K original miles and from the angle shown above doesn't look at all like a $2000 car. Regardless of how clean it looks now it was still a hot mess when purchased.

http://vorshlag.smugmug.com/photos/i...-Pq4jpMv-S.jpg http://vorshlag.smugmug.com/photos/i...-3bT7wzs-S.jpg
The entire interior is gutted, even most of the dash. We will finish what was started and put the dash cap back on

I will go over the issues on this specific car as we chronicle the repairs and upgrades to it this season. The previous owner (Brian Matteucci) has done a lot of repairs and refurbishment, and even a couple upgrades but we still have a laundry list of safety updates to tackle, as well as a few performance mods to "max it out" for TTC class points. We are keeping the car legal for TTC class so there aren't a whole lot of "points" we can burn on upgrades, so the car will remain stock in many aspects. Luckily, a stock 1992 Corvette doesn't suck!

Why is the C4 Still A Worthwhile Track Rat?

To understand why we consider this 24 year old car still relevant, we need to look at how this car was designed and what it came with that was ahead of its time. Here is a brief look at the C4 generation Corvette, which was produced from 1984 to 1996.

http://vorshlag.smugmug.com/photos/i...-r7n36Kj-S.jpg http://vorshlag.smugmug.com/photos/i...-5wNxQPr-S.jpg
We're already getting to work on this 1992 Corvette at Vorshlag. Parts are ordered and it was detailed by yours truly

GM calls the Corvette chassis the Y-body and it has been produced from 1953-current in 7 distinct chassis generations (see the Corvette Wiki). The "C4" generation was designed in the early 1980s and was delayed a bit before launched as a 1984 model (there was no 1983 Corvette). This chassis was a huge leap in sophistication from the C3 chassis it replaced. None of the subsequent Y-body chassis were this revolutionary - C5, C6 and C7 all share design aspects of the C4 and are instead mostly refinements (yes, the C5 had some serious updates!). The C4 was the first "Billion Dollar Chassis" design in the history of automobiles - and it doesn't share anything with any other GM chassis, so there was nothing to be gained for another, mass produced chassis (exception: almost all engines developed in the Corvette make their way into the F-body chassis and others).

With fairly low production numbers each year this has got to be a "loss leader" for General Motors at only about $40,000 when this car was new in 1991. And now with 3 newer generations of Corvette following the C4, this chassis has bottomed out in resale value - its not old enough to be considered a classic but its not new enough to be worth a lot of money. Some year C4s can be had for next to nothing, and even the later C4s can be snatched up cheap if it has any issues (like this one) and made into a low buck race car faster and more sophisticated than 75% of the cars at any given NASA race weekend. And this 1992 model one of the best of the C4 generation.

Engines: The C4 had 4 major engine designs in its 13 year run (1984-1996), which began in 1984 model with the abysmal Cross Fire V8. This was a horrid, 205 hp, early attempt at a fuel injected V8 and a complete carryover from the outgoing 1982 C3 Corvette. The Crossfire L83 has ZERO redeeming qualities and was only used for one model year in the C4. Starting in 1985 was the 5.7L L98, better known as the Tuned Port Injected or "TPI" V8. These long runner intake equipped V8s had LOADS of low end torque but petered out above 4000 rpms. With aluminum heads this "Gen I" Small Block Chevy (SBC) made decent power for the early 1980s (230 hp then up to 250 hp) but stuck around far too long (through 1991 model).

This was followed by the revolutionary 300hp 5.7L "LT1" Gen-II V8 in 1992, considered the first new design in the Small Block Chevy's long history (hence the Generation II engine; the LS1 in 1997 was the Gen III). There's tons of data out there about this motor, of course. In 1996 there was a special edition version of this motor called the "LT4" made 330 hp. Lastly, during the middle of the C4 model run was the LT5 DOHC V8 that came in the ZR1 (1990-95, 385-405 hp), which was a technological marvel for its time but was quickly overshadowed by the all aluminum OHV V8 that came out in the C5 - the LS1.

http://vorshlag.smugmug.com/photos/i...-mgppkCM-S.jpg http://vorshlag.smugmug.com/photos/i...-8pxFWGp-S.jpg

The Gen-II LT1 engine was unique in that it only lasted 5 model years, but it was also used in the 4th Gen F-body (1993-97 Camaro/Firebird) and the Caprice/Impala (1994-96 B-body) as well as one Cadillac (1994-96 Fleetwood). The reverse flow cooling was a big change but other than the bump to 10.5:1 compression ratio, produced very little benefit, and this "reverse" cooling style (heads cooled before block) was dropped in the Gen III LS1. The distributor (Optispark) is very unusual; it is driven by the camshaft and tucked behind the water pump. It is somewhat problematic and prone to water damage, but the later '95-96 "vented" style works better and aftermarket versions better still. The intake manifold is about as far from the TPI motors as you can get - it has larger but very short runners which produce a higher RPM range and a much flatter torque curve than the tractor motor curve of the TPI.

The Y-body LT1 always got 4-bolt main bearing caps (the other's all had 2-bolt mains), but the 1992 Corvette's LT1 is unique in one key way. The TPI motors (1985-1991) all used a crude form of Fuel Injection called batch fire port injection, and used a Mass Air Flow meter to meter incoming air into the engine. These early MAF designs used a circuit board that was in the airstream and were problematic from day one. The 1993-96 Y-body and 1993-97 F-body LT1/4 engines went to a more modern hot wire element MAF with the electronics housed outside of the airstream. But for the 1992 Corvette (and 1993 F-body) this new EFI system wasn't ready and for one model year only GM went with a speed density air metering system (no MAF). This uses Manifold Pressure Sensor along with a atmospheric pressure sensor to read incoming air. This lack of a MAF means a lack of a restriction in the airstream for that one year - and the 1992 model ran the strongest of all of the LT1s in stock form.

The manual transmissions used in the early C4s (1984-88 models) was a Doug Nash designed "4+3" transmission – a 4-speed manual coupled to an automatic overdrive on the top three gears. It was designed to improve fuel economy but was mostly a steaming pile of crap. For the 1989-96 model Y-bodies, GM went to the Germans and they offered up the S6-40, made by ZF. It is an unusual transmission and parts are hard to come by, and shops have popped up like ZFDoc that specialize in rebuilding these brutes. This trans is nicknamed the "ZF6" and is big, heavy and very strong, if a bit noisy. With 6 speeds and 2 overdrives (.75 in 5th and .50 in 6th), it made for excellent fuel economy. The Borg Warner/Tremec copied these overdrives for the later T56. With the ZF6 tall 2.68 first gear, the "black tag" version is rated to withstand 450+ ft lbs of torque (and is much stronger with a modern carbon synchro upgrade). To quiet the noises, GM used a heavy dual mass flywheel, which tips the scales at over 40 pounds. The clutch is also strong and the Dana 44 rear differential out back is also a brute. The limited slip unit in these 44s tends to last decades... and I hope so because we're not touching it. The halfshafts are big beefy aluminum tubular units with U-joints (cheap to replace!) instead of CV joints, and the driveshaft is built the same way.


The body is fairly aerodynamic (low height, low drag, small front area) and works well at high speeds. The body panels are made of fiberglass - which is good considering it has some chunks missing, and fiberglass is easy to repair. Some damned fool drove this car through a barbed wire fence back in its' checkered past, which damaged the front bumper cover and body panels on the left side. The driver's door was trashed but the replacement doesn't match the car's white paint well, so that will likely get repainted at some point. I will patch the fiberglass that is damaged myself and prime it for later repaint.

continued below

Fair! 12-29-2014 05:33 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

Where Did This Car Come From?

So about 3 years ago an old friend, Brian Matteucci, wanted to build a NASA Time Trial car. He was a long time autocrosser and former SCCA W2W Club Racer and watched what we were doing in NASA. He liked the cost-to-seat-time ratio of the TT series of classes, which was why we were in it as well. I helped him understand the NASA TT rules as well as the confusing TT classing formula and points classing system. We bench raced several builds over a few weeks and came up with the C4. That was no accident - because we had both raced these in the past. My history with Matteucci goes way back to about 1989, when he was a racer in the Texas A&M Sport Car club racing in a notchback 5.0L Mustang... I was about a year ahead of him and happened to be racing the same exact type of car.

We were competitors and friends through college, both helped create a new and popular autocross class called Super Street Mod in 1990 (we used this class to help push the SCCA to create Street Mod), and were roommates after college when we both worked at our first jobs in Houston as engineers. He and I both used to love digging through rule books looking for ringer cars and rules to exploit. After college we both autocrossed C4 Corvettes for a time - he was in a 1987 Z51 while I raced a 1994 Z07, both in SCCA's Super Stock class. When his 87 Corvette's fuel pump died on day 2 at Solo Nationals one year he co-drove my C4 - and hated it. ;)

My 1994 Corvette Z07 running in Super Stock at Solo Nationals in 1998. It was on Hoosier DOTs but was otherwise bone stock

The differences between our cars was dramatic back then - at low speed autocrosses - but it was obvious to both of us that the LT1 was far superior to the TPI engines at higher speeds. Already owning a C5 Z06, when he suggested a letter class TT build 3 years ago I immediately suggested another Corvette, but one that was a 100% dedicated, no-compromise race car build. Jason and I here at Vorshlag had often talked about the TTC classing of the late C4, and after some discussion with Matteucci, he agreed that it had a lot of potential in this class. He went out and bought this mess for $3000, sold off the interior bits for $1000, and had a $2000 platform to build a TT lettered class car from.

During the next 2-1/2 years Matteucci proceeded to strip hundreds of pounds out of this car and replaced lots of broken OEM bits (24 years can take its toll on anything), while testing it at various autocross events along the way. He did this while he was very busy with work, building a new house and shop, building a chump car, and autocrossing his C5 Z06. In December 2014 he got to a good stopping point and I bought the car for a great price - along with a promise to let him co-drive the car with me in NASA TT. Amy and I did that last year and it was a good way to get us both out on track for less money spent - which fits this project well.

With our "Team Vorshlag" entry we can both drive the car for one entry fee, doubling the chances for a fast time (two sets of eyes and brains are better than one). Matteucci worked at Roush Engineering for several years, and while there was responsible for building and developing a fleet of Bonduraunt school cars when Ford was their supplier in the 2000s. He lived at the track for many months, driving these cars for hours every day, so he's no stranger to finding a good track set-up: he was paid by one of the biggest engineering/racing companies in the world to do just this.

http://vorshlag.smugmug.com/photos/i...-rFxGSnQ-S.jpg http://vorshlag.smugmug.com/photos/i...-tZhzZqx-S.jpg
Left: The factory power steering cooler is a huge double-pass unit. Right: I pressure washed underneath to help find an oil leak

Last but not least, Matteucci was also the designer of our first three initial camber plate designs when he started Motor-Force Engineering back in 2002. We bought his company (and IP) back in early 2006 and several of the current Vorshlag camber plates can trace their roots back to his initial designs. Other than some manufacturing aspects and tweaks to materials and coatings, they are for the most part unchanged. So he has a long history with me and Vorshlag, whether he wants to admit it or not, heh. When I picked up the car on December 20th I gave him a bunch of Vorshlag swag, which was part of the deal with the car - he has to wear this stuff at the track, especially if he is the one who gets the wins!

TT Classing Looks Solid

So if you look at the NASA TT (and PT) classification for Corvettes something jumps out at you (go to page 20 of the TT rules) - most Corvettes either require a dyno test for an initial base classing (C1-C3) or are just shoved straight into TT1/2/3 numbered classes (C5-C7). The lone exception is the C4 generation, which has 5 separate letter class listings:

MODEL........................................BASE CLASS...... MIN WT
Corvette C4 ('85-'91)............................ TTD**......3223
Corvette C4 ('92-'96) (LT1)................ TTC*.......3203
Corvette C4 (LT4 option) (330 hp)...... TTC**......3350
Corvette GS ('96).................................. TTC**......3350
Corvette ZR-1 ('90-'95).......................... TTB*........3500

While the TTD entry for the 1984-1991 "TPI" Corvettes might look the most attractive place to start at first glance, the minimum weight is higher yet they make a lot less power (230-250 hp) than the LT1s. With two stars it is already -14 points out of 19 in TTD class, and strapped with TTD's 245mm base tire size, so it would be nearly impossible to stay in TTD class, meaning it would need a lot of work to be competitive in TTC. Of course upclassing adds 20 points to play with, so it might make the 12:1 power to weight ratio of TTC, with some dollars and points burned on engine upgrades. The two LT4 powered cars (all 1996 6-speed cars and the '96 GrandSport) have an extra star (-14 points in class) and extra 150 pounds of minimum weight, but the only advantage being +30 hp over the LT1 it is not ideal (plus they are worth more money used). Likewise the ZR1 has +300 pounds more minimum weight (and boy were they heavy!) and its up a class (TTB) and has one star (-7), plus these are somewhat rare and pricey, and expensive to maintain and upgrade. Yuck.

So the lighter, rugged and simple 1992-1996 LT1 cars are really the best bet, in my mind. TTC seems like an odd place to class the 1992-96 LT1 Corvette - and it might well be, but it is pretty old and I doubt many (any?) have been competitively run in NASA TT or PT. We shall soon find out if this base class makes sense, because that's where we are going to run it.

TTC 1992 Corvette Build Basics

While several folks guessed we would be building a "C4 in TTB", nobody guessed the TTC angle. And why would you? With the base classing of TTC* we only have 14 points to play with in class, so how could it be as "fast" as I predicted? For one, it doesn't need any points spent on power mods to meet the max power-to-weight ratio, as it will easily make the 12:1 limit for the class. So we save points there. How do I know? I owned a nearly identical 1994 Corvette that I had dyno'd on a modern DynoJet, where it made 277 whp in bone stock form, back in 1996 (these cars were a hair under-rated at "300 hp" crank). Another TAMSCC racer (Mike Mclure) owned a 1996 LT4 Corvette and dyno'd it at 308 whp the same day on the same dyno (also under-rated by the factory). If you know your dyno numbers, you will see that the LT4 makes almost exactly what a stock LS1 makes in a C5 (~310 whp), and the LT1 just a little bit down on that.

http://vorshlag.smugmug.com/photos/i...-4z5zTJr-S.jpg http://vorshlag.smugmug.com/photos/i...-ftdSNMt-S.jpg http://vorshlag.smugmug.com/photos/i...-JHkNqH8-S.jpg
Left: The 12" front brakes are adequate but can be upgraded to 13" rotors "for free" (no points). Right: The ABS system is ahead of its time

The factory brakes are also ahead of other cars from this era and not much if any off of the C5. GM developed its best ABS systems on the Y-body and this 1992 model has one of the best of the generation. And while the 12" diameter front brakes seem a little wimpy on the Base Trim Model, which this car has, they aren't total junk. The calipers are twin piston floating PBR units, a cast aluminum design used on the Y-body, F-body, and even the SN95 Mustang Cobra, to name a few. We have found a way in digging through the rules and Base Trim Level of the 1992-96 Corvettes to upgrade the discs to thicker, 13" diameter discs for zero points (more on that soon), so that saves us points and only costs a few dollars.

http://vorshlag.smugmug.com/photos/i...-8SFbtMw-S.jpg http://vorshlag.smugmug.com/photos/i...-fKDp2jN-S.jpg
We will show better suspension pics in the next update, but these will do for now

Suspension is very advanced for the time period, and better than what many of us race with on brand new cars from today. Forged aluminum uprights at both ends pivot on double A-arms up front and a multi-link rear IRS. Both ends are sprung by a composite transverse leaf with factory monotube Bilstein dampers. Other than some freshening and an alignment we're going to leave that pretty much alone.

Last up is the tires. The late C4 was designed to house massive wheels and tires (factory used 17x9.5" on almost all packages and up to 17x11" out back). While we won't be making flares to house big wheels, which is kind of one of our "go to" first mods, we will blow almost ALL of the available class points on tires (more on that next time).

Why not bump up to TTB? Sure, we think this car could be just as competitive there at this class' more aggressive 10.5:1 pounds-per-hp ratio, but it would allow for a lot more mods, and that costs $$. The goal of this is to keep costs down, but with +20 more points to play with after upclassing we could easily spend an extra $10,000 chasing down the points and the top cars in TTB (S2000 + E46 M3). While this would be fun, that's not our goal for the 2015 season. We want to instead focus on the "free mods" that TT allows as well as spend our precious 13 points as wisely as we can, as well as show some of our best "race prep" and safety upgrades - that are the same for virtually all classes.

In the next post we will sow our first few mods - brakes and shocks - that are both zero point upgrades. We will also show our first point mod and show the behind the scenes upgrades and race prep.

What's Next?

I always close my build thread posts with a teaser for the next entry. Well we haven't done much to the car yet, so there's still a lot of track prep to knock out. We did order OEM replacement brake parts and shocks, all zero point upgrades which I will explain in my next post. The next biggest things the C4 needs before the first event are all safety related.

http://vorshlag.smugmug.com/photos/i...-ttD4sGs-S.jpg http://vorshlag.smugmug.com/photos/i...-WqmMkkL-S.jpg

In early 2014 our crew here built the cage and did all of the fire/safety/lighting upgrades for a 1987 Corvette convertible that was initially run in Lemons and Chump but lately has been competing in WRL series endurance events (also known as - the Poorvette). We learned a lot working on that car that will apply to this TTC build, of course. One of the items we will replicate on our car is the roll cage, but due to time constraints (3 weeks to go!) before the first race we will only make the main hoop, harness bar and rear downbars (4 point roll bar) for now.

http://vorshlag.smugmug.com/photos/i...-JhqVTBt-S.jpg http://vorshlag.smugmug.com/photos/i...-R9s8rxn-S.jpg

We will go back and complete the full roll cage structure this car after the first event, to make everything safer (and to add some more ballast weight). Unlike this black 87, our 92 C4 has a roof - but its just a bolt-on targa panel, like all hardtop C4s. That removable roof panel makes it easier to build the cage and provides some aerodynamic advantages over the drop top, but the rear (glass) hatch main roof support structure will still be in the way and make this one a bit more challenging to build.

http://vorshlag.smugmug.com/photos/i...-kVj49Rs-M.jpg http://vorshlag.smugmug.com/photos/i...-SVhGM8q-M.jpg
Left: This is the seat we'll be using in the TTC car. Right: An adjustable seat back brace is visible in this pic

Another area that needs some attention fast is the seat mounting. The OEM seat that came with the car BROKE at an autocross event, which Matteucci warned me about ahead of time. We bought this Kirky 56700LW aluminum seat (see above left) for the Poorvette, but the driver wanted something different so we were stuck with it. This TTC4 project will get a lot of those cast away parts, some of which are brand new. Since the seat is a touch on the big side (17" width) we will make a poured foam seat insert, as well as a seat back brace tied to the cage (see above right)

http://vorshlag.smugmug.com/photos/i...-TjNmzTm-S.jpg http://vorshlag.smugmug.com/photos/i...-4JTtZBc-S.jpg

Due to the weird floor structure of the C4 chassis (some parts are composite and some are sheet metal), and some damage from a previous owner (aka: the Crack Head that tore up the interior and drove through the barbed wire fence), we need to repair and reinforce the floor areas. These cars are tricky to safely mount a racing seat into, as well as ballast plates, both of which we will need to do. The car is already 200 pounds under minimum weight (including a 200 pound driver) and that will only worsen as we (legally) replace OEM body panels and rear glass with lighter weight alternatives. We will run this car at the 3203 pound stated minimum weight and NOT burn points on running a lower weight. Running lighter might seem advantageous but we would have to lower the power output as well (the 12:1 ratio doesn't change for TTC class even if you burn points to "run lighter than minimum").

http://vorshlag.smugmug.com/photos/i...-ZGrpSCW-S.jpg http://vorshlag.smugmug.com/photos/i...-mL2PFQ4-S.jpg http://vorshlag.smugmug.com/photos/i...-W8D9DjS-S.jpg

Two zero-point mods Matteucci already added include the Moroso 20185 road race LT1 oil pan (allowed under TT rules, page 36), which at $288 includes more capacity, a Kicked-Out Sump and Trap Door Baffling for improved oil control, built-in Windage Screen and a port for an oil level sensor. The QuarterMaster 7.25" triple disc clutch ($599) and flywheel are also zero point mods (see page 36) and knocked nearly 50 pounds out of the drivetrain mass. It makes this little LT1 rev quite nicely and shift very well at speed - but driving it around at low speeds is a BITCH and it unlocks a LOT of transmission noise. Don't have accurate pics of these mods yet, but when we take them apart I will get better images and weights. I will include these "zero point" aftermarket part upgrades costs into our build budget, below.


That's all for this time. I will post another update before the first race, January 17th at MSR-Houston, where we will debut the car in NASA's TTC class with me and Matteucci at the wheel. That's assuming everything goes smoothly! The next update will show some actual work being done besides my initial clean-up, and I will also lay out more of our game plan for the season, including which tires we plan to run with. They are 30mm smaller the stock size, but it will make sense why soon.


Fair! 01-09-2015 11:45 AM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for January 9th, 2015: The first stage of "initial race prep" for this project is getting down to the wire with the NASA race debut only ONE week away! Let's get caught up on the work we've been knocking on Project DANGER ZONE, our TTC class prepped 1992 Corvette. I had intended this to be a quick update, showing the initial stages of race prep, but I started writing and somehow this post spiraled out of control. It now includes some aero/drag reduction theory, the History of Iron and Steel, a good bit on roll cage tubing and design, some tire analysis, and other random tidbits of tech. If you get bored easily just skip down to the pictures and enjoy.

Safety First, Kids!

There are many Safety Upgrades we want to add to (or repair on) this Corvette during the 2015 season, which are the same for virtually any dedicated road race build. Unfortunately we were pressed for time and won't get them all done before the first race. The Safety list includes: a full roll cage, racing seat install, 6-point racing harness, window nets, full fire extinguisher system, secondary 2.5 pound fire bottle, tow hooks at both ends, tie-down hooks at both ends (for towing), replace the broken windshield, replace the rear hatch glass with Lexan or Plexiglass, and more. That's a lot of parts and work on the "Punch List", but as far as what's "required" for NASA Time Trial, that is much less. We also have some repairs and performance upgrades to tackle, too. We got almost nothing done over the holidays (short weeks, busy on customer cars) so let's see what we can get done in two weeks.

Windshield + Small Aero Improvements

This repair is really a safety upgrade, because you cannot race with a busted windshield. Before I bought the car from Matteucci he had warned me about this problem - it had a lot of big cracks on the passenger side and chunk missing where the OEM rear view mirror attached, with the cracks propagating into the driver's view. The upper right corner of the windshield trim and weatherstrip took a hit when a former owner (ie: The Crackhead) drove it through a barbed wire fence. Matteucci literally found a crack pipe (maybe a meth pipe) in the car after he bought it. So yea, now you understand part of why this was a $3000 running and driving car purchase.

Nasty, broken windshield and trashed weatherstripping has to be replaced

We discussed delaying the windshield replacement because when you install a roll cage it is ALWAYS easier (and often required) to get the front windshield out of the way to access and weld tubes along the front of the cage. In some cars with a fixed rear glass window, that is often removed as well. The cages we built in the two cars below required the windshield to be out. At left is an SCTA legal cage for 200+ mph use on the salt flats, which has more of a "Funny Car" drag racing cage (built per the rules). To weld in the the front tubing gussets requires windshield access. The one at right is a NASA ST3 legal Mustang the the dimple-die gussets and front corner tubes need windshield access - as does a proper paint job on any cage.

http://vorshlag.smugmug.com/photos/i...-fcbC2Jp-S.jpg http://vorshlag.smugmug.com/Projects...B61G8468-S.jpg

We knew we wanted a roll cage in DANGER ZONE (to reduce the "zone of danger"), but with only 2 weeks of time build available after the short holiday weeks between Christmas and New years, and many other items that needed attention, meant only building a 4-point roll bar for this first race. Which meant the windshield didn't need to come out. But it was so cracked that it would never pass tech, so it had to be replaced. And when we go back and finish the full cage, out it will come again!

http://vorshlag.smugmug.com/photos/i...-F2CsJkK-S.jpg http://vorshlag.smugmug.com/photos/i...-5h6vmRp-S.jpg

We called our buddies at Titan Auto Glass and they extracted the old and busted and installed the new hotness. There are normally several windshield choices for most cars, varying in price, but for 24 year old Corvettes there was one - and it was a tick pricy at $260 installed. But hey, can't race with a busted windshield. Going to Lexan is an option but there are more downsides (more costly, harder to install, easily scratched, difficult to use wipers with them, more easily nicked by rocks or tire klag) than upsides (slight weight savings). A two layer, laminated, glass OEM style windshield is preferred by many racers when they have a choice.

http://vorshlag.smugmug.com/photos/i...-PXJF8B2-S.jpg http://vorshlag.smugmug.com/photos/i...-bJjWk5c-S.jpg

The OEM windshield surround rubber weather stripping was a total mess (above right). Matteucci had cut away the bits around the A-pillars when he gutted the interior and the top bit was destroyed by the barbed wire. The crackhead former owner had filled in the missing chunk in the rubber seal with SHOE GOO, and that had to be chiseled away (thanks Titan!).

I wasn't about to put this mangled mess of rubber seals back on, but we needed the top bit of rubber to seal the targa roof panel smoothly along the top of the windshield and I also wanted the seals back in place along the edge of the windshield at the A-pillar. This should help smooth the airflow in a high payoff "Green Zone" of potential drag reduction - the edges of the windshield. Read this NASA Speed News article called "Getting Into The Zones" (page 60) written by aero guru Neil Roberts (also read his ThinkFAST Engineering blog for more great articles!) and that will make more sense.


A smooth, new set of weather stripping should help aid the transition from the edge of the windshield (sides and top), reducing drag. We are looking to reduce drag in ALL of the Green areas (again, read Neil's article) on this car, and do so legally. We cannot run NASA events with the windows up, so the door window openings have to stay. We have tried to read the rules to say otherwise, but rule 7.2 of the NASA TT rules is pretty clear:

7.2 Front driver and passenger side fixed/Lexan windows are specifically not permitted unless they are factory installed during the manufacturing of the vehicle. Both front side windows must otherwise be in the down position while on track."

Running the windows UP would be a decrease in drag but it is not allowed in virtually any form of road racing, for safety reasons (easier extraction after a crash). Some drag racing classes and high speed events like Bonneville do allow for side windows, so the silver Subaru we're building the cage for above is getting a full Lexan window package (4 side windows + front and rear windscreens).

Why Terry Needs A Roll Cage

There isn't any additional safety requirements in NASA Time Trial groups than what is called for in HPDE run groups: a Snell SA2010 rated helmet and OEM seat belt, plus a roll bar for convertibles. There isn't supposed to be wheel to wheel contact in TT, but we are running for times and competing for contingency prizes, and many TT racers take it pretty seriously. I won six sets of Hoosier race tires racing in NASA TT3 class in 2014, and these were BIG tires that cost $1710 a set, so there is some decent swag on the line. When you are chasing a TT win you often push the limits and do stupid stuff...

Crap like this

My personal safety record, for the amount of laps I've driven on track, was pretty damned good up until 2014. In 27 years of running on road courses I only had a couple of "offs" that were worth mentioning. I de-beaded a couple of tires in a high speed off at TWS in the late 1980s that curled my hair a bit. A number of times I've had a quick "off and on" that bent a splitter or packed a grill with grass, sure. The stock brake pads came apart and I left Turn 7 at ECR at 90+ mph in 2013 in a stock '13 Mustang. But by far my most memorable off-track experience happened in 2014 (shown above).

After the crash I began wearing a HANS device and fire suit to complement the FIA halo seat, 6-poiont harnesses and roll bar in our TT3 Mustang

I briefly mentioned this in my first post, but it was a pretty spooky incident and I figured it might explain my "overkill" safety requirements for this TT build. After losing brakes at at Road Atlanta at a Global Time Attack event in May 2014, I went off the end of Turn 10A at 150mph, through the gravel trap, and took a big vertical hit coming out of a trap. I got hurt but the car barely took a scratch (splitter came off, was repaired and reinstalled and back on track 2 weeks later, but not with me driving). Even though I had a proper FIA halo seat, good harnesses, and a good roll bar, I wasn't wearing a HANS device. We think this might be why I fractured a vertebrae in my back and broke a rib. After this incident I was in a lot of pain, wearing a back brace for 2 months, and not racing.

http://vorshlag.smugmug.com/Projects...fitted_L-S.jpg http://vorshlag.smugmug.com/Projects...ng-chart-M.jpg

Having gone through the crash scenario many times and analyzing frame-by-frame pictures of the crash since, the injury seems to come down to too much "arching" of my back in the impact that broke these bones. A properly worn HANS device would have likely prevented this injury. The "off" happened because I ran out of brake pads, and had been ignoring measured brake caliper temp data of 490°F+ for months. I'm not going to make those series of mistakes again, and I also vowed in 2014 to start racing with better personal safety gear. I was setting a bad example and I needed to do better.

http://vorshlag.smugmug.com/Projects...B61G8907-S.jpg http://vorshlag.smugmug.com/Projects...B61G8908-S.jpg

So obviously, after this back-breaking scare I'm taking my safety on track a lot more seriously. I've starting using a HANS device (still haven't picked my favorite model after trying 4 different brands - and I'm about to try the brand new Schroth HANS design, since we are a dealer) and an FIA 3-layer driving suit in all TT events. I am also wearing my harnesses TIGHTER and keeping a much closer eye on things like brake fluid temps and brake pad material depth, so this scenario of failures never happens again.

Roll Cage Is Safety More Than Performance

The steel frame structure of the C4 Corvette. This is a 1984 model

After the personal safety gear, the next most important safety aspect of any race car is the roll cage. This structure is helpful to make the chassis more rigid, sure, but it is there mostly to prevent bodily injury in many types of crashes and "offs". These include single car off track frontal collisions with a barrier (somewhat common), a roll-over crash (very rare), or any car-to-car contact (more common). While a roll cage wouldn't have helped me in my gravel trap "jump" incident at all, there are other types of crashes where it could save your life - and do so more effectively than the basic 4-point roll bars we have used in my last 3 personal race car builds. I own a shop that builds roll cages and haven't had one in my own cars in 6 years... that's crazy.

http://vorshlag.smugmug.com/photos/i...-F7ghcfN-S.jpg http://vorshlag.smugmug.com/photos/i...-d77x9WB-S.jpg

Corvette roll cages are tricky. All Corvette chassis generations (C1-C7) have a strong metal frame (steel frames through the C5, with aluminum frames for C6 Z06 and all C7s) with a composite body attached to it. Adding a roll cage to these cars has some extra challenges, since you need to cut away fiberglass to access the metal frames, but its nothing we haven't done before.

As I spoke about above, TIME is not on our side for this first NASA event, so we had to cut back on the roll cage plans for the maiden voyage. We could have bought a second-hand 4-point roll bar but it would never fit as tight to the roof structure in this gutted car (they are usually made for full interior cars).

http://vorshlag.smugmug.com/photos/i...-Qrc5HKc-S.jpg http://vorshlag.smugmug.com/photos/i...-Fzb47DR-S.jpg
Frame differences on the 1984-1991 (left) and 1992-1996 (right) C4 Corvettes

Quick sidebar: the C4 Corvette had major changes to the suspension (1989) and even to the frame (1992), along with major changes to the drivetrain (1989 for ZF and 1992 for LT1), front crossmember, and transmission tunnel over the 13 year long model run. The two "body shop spec" images above show the changes to the frame at the 1992 model year, and we've noticed a lot of other differences to the interior fiberglass structure.


Last year we caged and safety prepped a 1987 Corvette convertible (shown above) and after looking at pictures of both that and our 1992, it had a lot of structural differences at the tunnel, firewall, and rear bulkhead (behind the front seats), not to mention the dash, body, and other obvious differences. The frame was also different in some key areas. We are using the NASA CCR for cage design specifications on our car, but the black 87 used a mix of NASA, WRL, Lemons and ChumpCar series cage rules.

A Brief History of Iron and Steel

OK, this is a big tangent. It might not be boring to a racer - unless you are a metallurgical engineer. Modern race car roll cages are made from steel tubing (aluminum is not allowed) and picking the right alloy and type of tubing for the job involves both a rule book (General Competition Rules or GCR/CCR) and some engineering knowledge. There are generally TWO accepted types of tubing allowed for roll cages in SCCA and NASA: 4130 Alloy steel and 1018/1020 Low Carbon (aka: Mild steel) Steel DOM tubing.


Working as a Mechanical Engineer at a foundry in my first job out of college exposed me to a lot of practical metallurgical design and lots of different steel alloys. I also took a welding class at college, where we talked a lot about steel and iron and the changes welding can do to metal's molecular structures. That's where I learned that steel is the best metal on planet earth, and in many ways unique among all metals.

Iron is is, by mass, the most common element on Earth, forming much of Earth's outer and inner core (same scenario in almost any rocky planet). It is also the fourth most common element in the Earth's crust, which means it is relatively easy for humans to get at and mine. The production of iron by humans began sometime around 2000 BC and was so significant it began what is now called the Iron Age - when iron replaced bronze in implements and weapons. This shift occurred because iron, when alloyed with a bit of carbon, is harder, more durable, and holds a sharper edge than bronze. For nearly four thousand years, until replaced by steel after ~1870, iron formed the material basis of human civilization in Europe, Asia, and Africa. Iron has shaped human history for the past four thousand years, and it's use accelerated technological growth.


Natural "iron ore" has a lot of oxygen in it, so it is smelted at high temperatures to extract a more pure mass of iron. Carbon naturally gets mixed in at these high temperatures (along with 2-3 other elements) which means cast iron has a relatively high proportion of carbon (3-4.5%). This makes cast iron hard and brittle; it is liable to crack or shatter under a heavy blow, and it cannot be forged.

Blacksmiths learned to work iron - after heating it in a furnace at high temps they removed a pasty mass and hammered it on an anvil to drive out the cinders and slag and to compact the metallic particles. This Wrought iron (“wrought” means “worked” or hammered) contained generally from 0.02 to 0.08% percent of carbon (absorbed from the charcoal), just enough to make the metal both tough and malleable. Wrought iron was the most commonly produced metal through most of the Iron Age.

Steel alloys have a little bit of carbon in them (0.2 to 1.5%), enough to make them harder than wrought iron, but not so much as to make it as brittle as cast iron.

continued below

Fair! 01-09-2015 12:02 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

Its hardness combined with its flexibility (from some other alloying elements) and high tensile strength make steel far more useful than either type of iron: it is more durable and holds a sharp edge better than the softer wrought iron, but it resists shock and tension better than the more brittle cast iron. After about 1856 (the invention of the Bessemer converter) and into the 1870's (Andrew Carnegie's grasp of the vital importance of chemistry in steel making) steel alloys became cheap to manufacture and exploded in use, replacing wrought iron rails in railroad tracks and other uses.

Some of the sources I used, other than past knowledge: This and this and that, and more.

Modern Roll Cage Steel Choices - 4130 vs 1020/1080 Alloys

There are two basic steel alloys used in roll cage structures and we will start with the "stronger" and more expensive alloy allowed: 4130. AISI 4130 alloy steel is about 97% Iron and has 6 other alloying agents that make up the last 3%. Chromium (0.80 – 1.10%) Molybdenum (0.15 – 0.25%) are the two key elements added that give this metal its higher tensile and yield strengths, and are the two most expensive elements in the alloy as well - hence the nickname "Chromoly Steel". These alloys are harder to weld properly (generally they are only TIG welded) when compared to Low Carbon/Mild steels. The yield strength of 4130 is 66,700 psi (67 KSI) and when this metal is used, a little LESS of this alloy is needed to achieve the same total assembly strength as Mild steel. It has a good strength to weight ratio, but the same density as all steels (all steel alloys and iron have nearly the exact same density, .284 lbs/cubic inch, due to the fact that all steel alloys are still almost entirely made of iron). In the past, roll cage rules allowed for thinner 4130 tubing to be used relative to Mild Steel, but that is no longer the case for most road racing bodies.

I used to use a lot of "A36" mild steel 15-20 years ago when I designed oilfield equipment, which had a minimum yield strength of 36KSI, which is relatively soft and very cheap. The modern 10XX series steels have gotten better and a lot stronger - closer in strength to 41XX Chromoly steels, but without the negatives. AISI 1018 and 1020 "Low Carbon" or "Mild" Steel alloys (also known simply as Carbon Steel) are lower cost and slightly weaker than 4130, but these 10XX series alloys have excellent weldability and offer a good balance of toughness, strength and ductility. Once cold worked (via the DOM or CDS process) these Mild steels become even stronger and stiffer.

1018 steel (0.14 - 0.20% Carbon) has a yield of 54KSI and 1020 steel (0.18-0.23% Carbon) has a 51 KSI yield - which isn't that far off of 4130 (67 KSI). Ultimately 4130 is about 20% stronger than Mild steel. But 1018 tubing that is DOM cold worked gets stronger, and is rated at 70KSI, and 1020 DOM tubing is rated is 65 KSI. Cold working 4130 tubing via the DOM process turns it up to 90 KSI yield... roughly 22% stronger.

http://vorshlag.smugmug.com/Projects...B61G5247-S.jpg http://vorshlag.smugmug.com/Projects...DSC_4623-S.jpg

The key benefit to racers building roll cages out of Mild steel over Chromoly is that 10XX alloy steel is much more forgiving with respect to weld embrittlement and tends to "crash better" than the harder "alloy" steels. When you weld the 41XX series alloys the molecular structure of the alloy changes near the heat affected zone, especially if you put too much heat into the weld (and some welders like to "weld hot", which can really make the weld area change), so 4130 cages are almost exclusively welded with the trickier TIG welding process (a Tungsten tipped torch with a shielding gas and a separate metal rod, with a variable control on the welding arc).


Mild steel isn't nearly as susceptible to this issue and can be TIG or MIG welded and generally does not lose much strength at the welded joints. 10-20 years ago 4130 was all the rage for roll cages but lately 1018 or 1020 Mild steel is the norm, as long as they are DOM. To me nothing beats a properly designed, TIG welded, Mild Steel DOM tubing roll cage. This has the best combination of variables and the least number of compromises.

DOM vs ERW Tubing?


ERW or "Electro Resistance Welded" tubing is how steel tubing and pipe is made (at least initially) - where a continuous, flat roll hot rolled steel is bent around round (or square or rectangular) dies and welded at a seam (see image above). That's how lower cost pipe and tubing is left - with this visible welded seam on the outside and often a physical "ridge" on the inside of the tube (see below). This problem is - seam ultimately becomes the weakest point in this type of tubing. And the hot roll plate material isn't ever as strong as cold worked steel.

http://vorshlag.smugmug.com/photos/i.../i-5XXNJVf.jpg http://vorshlag.smugmug.com/photos/i...-s28PS45-S.jpg
A visible seam and often a raised ridge is the result of the welding process from ERW tubing. All tubing starts as ERW...

The DOM process (Drawn Over Mandrel) takes ERW tubing and "cold works" it by drawing over a round mandrel and through round dies, inside and out. This makes the now DOM tubing "seamless" (its really hard to find the seam with your eyeball) and work hardens the steel structure - adding strength and removing the stress riser at the seam. ERW tubing was previously allowed in roll cages (up until just a few years ago) and the various CCR/GCR rules sometimes still reference ERW for "grandfathered" cages built before it was outlawed, but nowadays all roll cages are spec'd as seamless tubing - either 1018/1020 Mild Steel (DOM or CDS) or 4130 Alloy steel (DOM or CDS). There's another cold working seamless tubing process nowadays called CDS (Cold Drawn Seamless), but I can't seem to find any CDS tubing in common roll cage sizes - yet. The CDS specification seems to be more common in Europe. It could be the exact same process as DOM, but some U.S. tubing companies specify them separately, so I don't know.

The stiffness difference between ERW and DOM is shown in this video, with the same diameter and wall thickness tubes of both types in a side-by-side bending test. The lower strength of ERW + the stress riser of the seam are why it isn't specified in roll cages any longer, but it was a pretty recent deletion from roll cage specifications.

The FIA has updated their specified tubing to 350 N/mm2 (50.76 KSI) tensile strength (see page 46, rule 8.3 of Appendix K here), and material is simply listed as "Cold drawn seamless carbon steel". They used to only spec 4130 alloy tubing (or the European equivalent) but even the French have seen the benefits of using Mild Steel DOM/CDS tubing. As we have seen with changes to rules specs, ERW is no longer allowed and the advantages in welding Mild Steel outweigh the weight savings or 20% strength benefits of 4130 Chromoly.

Picking the Tubing Material, Tubing Sizes and Cage Design Layout

OK, that got a bit long, but it was hopefully worthwhile tech. Now that we know why we use steel, know more about the alloys, understand the benefits of the cold working and seamless processes that are required in the steel tubing specified, and why more cages are using mild steel DOM - let's pick the cage tubing size for this build and show some Corvette cage pictures already!

http://vorshlag.smugmug.com/photos/i...-RN4gtX5-S.jpg http://vorshlag.smugmug.com/photos/i...-2nJgS56-S.jpg

Many of the cars we work on at Vorshlag lately, that are built around NASA specs, weigh over 3000 pounds so we're often using 1.75" diameter x .120" wall thickness DOM Mild steel tubing. And since the 1992-96 C4 Corvette is listed as a base class of TTC and a Minimum Competition Weight of 3203 pounds, I assumed that we had to use this tubing size. This is nearly the heaviest cage tubing in all of the NASA CCR, but lower weight cars can use thinner tubing diameters and wall thicknesses, as shown below (copied from the 2015 NASA CCR).

NASA 15.6.18 - Roll Cage Tubing Sizes

For the purposes of determining roll bar tubing sizes, vehicle weight is as raced, but without fuel and driver. Minimum tubing size for the roll
cage is:

Up to 1500 lbs:
  • 1.375” x 0.095” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM
  • 1.500” x 0.080” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM

1501 - 2500 lbs:
  • 1.500” x 0.095” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM

2501 - 3000 lbs:
  • 1.500” x 0.120” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM
  • 1.750” x 0.095” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM

3001 - 4000 lbs:
  • 1.750” x .120” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM

Over 4000 lbs:
  • 2.000” x 0.120” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM

Since we do not need to include the weight of the driver (200 pounds) or fuel (20 gal x 6 pounds/gallon = 120 pounds), that means our goal weight of 3203 really translates to a caged race car weight of about 2900 pounds. So we can use the lighter 1.75" x .095" wall DOM Mild Steel tubing. I like this for two reasons. First, we have a bunch of this tubing already in stock at the shop. And two, we typically bend 1.75" tubing, so our tubing bender has this set of dies already installed. Right now we're building two cages at once, both with 1.75" diameter tubing (one is .095 and the other is .120" wall), so we won't have to keep switching the dies. This thinner wall tubing is also easier to bend.

http://vorshlag.smugmug.com/Projects...DSC_4256-S.jpg http://vorshlag.smugmug.com/Projects...B61G2762-S.jpg
We use a JD2 Model 32 manual tubing bender and dies

The weight is not insignificant: 1.75" x 120" wall DOM weighs 2.089 pounds/foot of tube length. The 1.75" x .095" wall DOM weighs 1.679 pounds/foot (19.6% lighter and about the same amount cheaper). The other choice for this weight is 1.5" x .120" wall DOM, which weighs more at 1.769 pounds/foot. Sure, we could have stepped up to a larger tubing size, but those CCR minimums are there for a good reason... mega-sized tube in a smaller/lighter car makes for less room to the driver and less energy absorption in a crash, so we're going with the recommended tubing range for a 2900 pound car, then picking the larger tubing diameter of the two options given there, which is slightly lighter.

Cage Layout and Design


There are three cage design options we can choose form the NASA CCR, shown in 15.6.8, -.9 and -.10. We're going with the "Forward Hoops" version from 15.6.8, shown above. This is the most common of the 3 methods (another is the "Halo style") and makes for the most room for the driver's head in a car like this. So about halfway through the day on Friday the 2nd, our fabricator Olof stared work on the cage install. He will build a majority of this cage while Ryan finishes a cage on another car at the same time.

http://vorshlag.smugmug.com/photos/i...-3vr9X7b-S.jpg http://vorshlag.smugmug.com/photos/i...-kKPfv9V-S.jpg

Before you can start bending any tubes you have to clear out the interior. This car was already gutted, which saved us 15-20 hours of labor. That work is never included in the "cage" price, which some people don't always understand. If you want to save some money, bring in a NAKED car with zero interior bits, like this. I came in early that Friday and removed the driver's seat and targa top, then the guys pulled the rear hatch glass off.

http://vorshlag.smugmug.com/photos/i...-Czvns8H-S.jpg http://vorshlag.smugmug.com/photos/i...-VZwPfJZ-S.jpg

The driver's seat normally weighs more than this, but it was alreay partially gutted by Matteucci and only tipped the scales at 34 pounds - I've weighed a lot of modern power front seats in the 60-75 pound range. The targa top weighed less than I had thought at 22 pounds. This is the plexiglass "See through" version, but I'm looking for a fiberglass version (both were offered from the factory) which we could paint white to match the car, but they sell for $$$ used. The weight is mostly in the metal frame structure, so the Plexiglass vs Fiberglass is probably a wash - except the fiberglass OEM version is likely stiffer. We might replace the Plexiglass with a custom Carbon Fiber skin (stiffer than Fiberglass). Is it legal? Well since we can run with the targa top removed (wouldn't that make its construction insignificant?) and as I read TT rule 8.3.B, we can lighten the "roof, hood, body panels and doors" as long as they "maintain their BTM (Base Trim Model) size and shape". The "no points" listing for I.h.20 says the same thing, with more details with respect to carbon/fiberglass doors being legal as long as the BTM body lines, hinges and handles are still operational. And an in-house built Carbon Fiber roof would be, you know, cool...

http://vorshlag.smugmug.com/photos/i...-kWNS7Pd-S.jpg http://vorshlag.smugmug.com/photos/i...-DH53kJT-S.jpg

The rear glass was much heavier at 46 pounds. That bit will likely never go back onto this car, as we have a formed, 3/16", trimmed Plexiglass rear hatch replacement inbound that should save 30+ pounds. I will show that in my next post, if it gets here before the NASA race Jan 17th. This is legal per the "No Points Modifications" rule I.b.8, as long as it has the factory BTM shape and no uncovered holes.

http://vorshlag.smugmug.com/photos/i...-c2jCxxN-S.jpg http://vorshlag.smugmug.com/photos/i...-4rLbqMv-S.jpg

Once the interior was cleared out enough to start Olof began cutting bits of fiberglass out of the way. See why I had the pictures of the C4 frame structures up above? That was to help us find where the frame is - which isn't obvious in some areas as there are big gaps between the shape of the interior fiberglass structure and the metal underneath.

http://vorshlag.smugmug.com/photos/i...-ccLwp7m-S.jpg http://vorshlag.smugmug.com/photos/i...-rLKRCPQ-S.jpg

If you ever get a roll cage quote on a Corvette, now you know why it costs more than a traditional steel unibody car - because you have to cut access holes to get to the frame. And they need to be fairly big holes, to give the fabricator access to weld a reinforcement plate to the frame. Then you have to close up the holes in the fiberglass later... all of that is extra work.


Once you have access to the frame structure it has to be cleaned of all paint (we use a pneumatic wire brush tool called a "Crud Buster" along with a flap disc on an electric angle grinder). Then the plates are drawn in cardboard and transferred to steel, in this case 1/8" thick hot rolled plate (minimum thickness is .080" for these plates, but we tend to use .125", since it is stronger and easier to weld).

http://vorshlag.smugmug.com/photos/i...-R6n7Qfb-S.jpg http://vorshlag.smugmug.com/photos/i...-scg9cBW-S.jpg

Olof cut the plates and tack welded them to the frame at the main hoop, which is in an unusual spot. Normally the main hoop mounts to the floor behind the driver's seat - often 6-8+ inches behind the back of the seat. But in a Corvette, for tall-ish folks, the back of the seat ends up right at the rear bulkhead, so the main hoop has to go up on the rear deck area. The frame extends up here and we've checked with NASA inspectors on Corvette cage hoop placements and have also built cages in Corvettes like this. Miata cage main hoops are done the same way - just the nature of these 2 seat cars and their compact interiors.


On Monday the 5th, Olof designed and bent the main hoop, with help from our head fabricator Ryan. They got the hoop TIGHT up against the high strength steel roof structure, and placed it back the correct distance from my head. We had already done a number of seat mock-ups at this point and we knew where I needed to sit - with the seat almost touching the rear bulkhead. This put the main hoop where it is above.

continued below

Fair! 01-09-2015 12:18 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

http://vorshlag.smugmug.com/photos/i...-vZPsrTW-S.jpg http://vorshlag.smugmug.com/photos/i...-4kRP28K-S.jpg

By this point we had switched our focus from the larger Kirkey aluminum seat we had in stock, to a PORNO RED! Cobra Suzuka Kevlar FIA seat we "horse traded" with a friend for. My buddy Jason McCall had ordered this seat from us last year for his 1989 Corvette but it wasn't fitting with the electric seat adjuster he wanted to use (for better fit with his shorter co-driver - his wife). It is brand new and still good through 2019 on the FIA certification.

http://vorshlag.smugmug.com/photos/i...-4PNGs8V-S.jpg http://vorshlag.smugmug.com/photos/i...-BsgPs7K-S.jpg

This seat happened at the 11th hour - the day Olof needed to start on the seat mounting and to lay out the harness bar. It turns out our aluminum seat fits better in his full interior C4 and his composite Cobra seat fits better in my gutted C4 with no slider. So we made a seat swaperoo!


Once more access holes were cut in the rear fiberglass (shown below left) the rear downbars could be cut, notched and built. These will land on 1/8" thick pads on top of the frame, as shown. Two thickness of pad, actually...

http://vorshlag.smugmug.com/photos/i...-zFKN2ZD-S.jpg http://vorshlag.smugmug.com/photos/i...-7RWtHV6-S.jpg

One of the compromises made from our reduced timeline was that the cage became a weld-in 4-point roll bar, and then when we looked at the next step, it became a bolt-in roll bar. Now before you hurl insults, you have to realize that this is going to be a VERY beefy design that can still become a proper weld-in roll cage shortly after the first race. Weld-on "nut plates" (see above right) were created and access holes for the nuts were cut in the frame. This is because the frame is fully boxed and we couldn't bolt into the frame otherwise. These plates have nuts welded to the back side and will be seam welded to the frame, then a matching "footer" plate from the 4 main tubes will land onto these and bolt in place.

All this bolt-in nonsense was done for future access. After our first TT event we have a month off before the SCCA Club Trials event at TWS. During this break we can take the time to turn the 4-point roll bar into a fully welded in 6-point roll cage. The front cage section and door bars take the most time to fit, and we ran out of time. But to do the final welding on the door bars and A-pillar tubes, the cage has to be rotated forward and down, and this bolt-in rear layout will allow for this rear section to be moved for that access. Once the final welding is done up front the four "footers" of the roll bar portion will be welded to the frame plates, and the bolts can be removed. Make sense?

http://vorshlag.smugmug.com/photos/i...-Kz7rcXp-S.jpg http://vorshlag.smugmug.com/photos/i...-HSmHTbZ-S.jpg

Yes, that's a little crazy, but our 2 week timeline was just too tight to fully cage the car AND do all of the other performance, safety and maintenance work needed. Next up in the roll bar design is the main harness bar (which the shoulder harness straps will wrap around), then the main hoop diagonal. This is a horizontal bar that is kicked back from the main hoop about 5 inches, to allow for the shoulder harness adjusters to loop around the bar.

http://vorshlag.smugmug.com/photos/i...-K4JBrgt-S.jpg http://vorshlag.smugmug.com/photos/i...-xSTfzHm-S.jpg

The diagonal bar was cut and being tack welded in right before I made this post on Friday Jan 9th. One more tube is needed for the roll bar (a short tube connecting the harness bar and diagonal) and then it will come out for TIG welding. All of the pictures shown were just tack welds, which were done with the MIG. I'll show the rest of the roll bar and all of the other work happening next week in my follow-up "initial race prep" post. Gotta wrap it up!

Seat Mounting

Mounting a racing seat into a car is NEVER a fun job - installing a real racing seat is always a LOT more work than you might think. Ask any race car fabricator and they will tell you that this type of job sucks. We've installed a lot of racing seats over the years and it is never an easy "bolt-in". Any off-the-shelf seat bracket we've ever seen usually needs massive modification, and some of them raise the seat height by 2-5 inches. They only seem to work for little tiny short European children. Its a dirty little secret in motorsports - bolt-in seat brackets for fixed-back seats almost never fit.


And this only gets worse with drivers over 6 feet tall with racing helmets adding another 2-3" to their torso height. At 6'3", I'm not a good fit in many OEM seats much less with a racing helmet added. Here at Vorshlag there are 5 people that are 6'2" tall or taller, so we're all used to these seat mounting headaches. The Corvettes from C4-C7 are all pretty cramped inside as well, and we've had to really fight to make racing seats fit in these cars.

http://vorshlag.smugmug.com/Vorshlag...1%20copy-S.jpg http://vorshlag.smugmug.com/Vorshlag...0%20copy-S.jpg

In the most difficult situations (cramped cabin + tall driver) it is not uncommon to spend 6-8 hours fabricating mounts for one seat. Adding in a slider makes this take even longer, but we were out of room here and just mounted the seats directly to the floor (my co-driver Matteucci is almost the same height, luckily).

http://vorshlag.smugmug.com/photos/i...-wmzscbx-S.jpg http://vorshlag.smugmug.com/photos/i...-R7vP596-S.jpg

Olof took most of a day to test fit the seat (with me sitting in it in a helmet), mock-up the angles and height, reinforce the floor, then modify the OMP side brackets (see image in this section) to get the seat bolted in where I had enough head room to the targa roof with a helmet on. It was tricky and he lowered the "lowest" mounting holes in the OMP brackets by about 5 inches. The original OMP seat mounting holes are crazy tall - doesn't matter what brand of brackets, this always happens.

http://vorshlag.smugmug.com/photos/i...-Ch7RVwP-S.jpg http://vorshlag.smugmug.com/photos/i...-rFT8LhC-S.jpg

I don't have good pictures of the seat mounting from underneath, with the car in the air, but we have beefed up all of the seat mounting points to the chassis. The rear studs were removed and an 1/8" thick doubler runs across the entire width under the steel floor pan section. The front studs were also reinforced. We are adding clip-in harnesses so eyelets with reinforcement plates will go in for lap belt anchors as well as a solid mount for the anti-sub belt under the seat. Will show all of this next time.

Tires Are Everything

Its time to talk about the single most important aspect of this TTC build - the wheels and the TIRES.

http://vorshlag.smugmug.com/Projects...DSC_4805-S.jpg http://vorshlag.smugmug.com/Projects...DSC_1126-S.jpg

Tires are the most important aspect of a road race car. Let me repeat that for emphasis: Tires Are The Most Important Thing In Racing. The four tire contact patches are the only things connecting your car to the race track. Through these four little patches all of your forward accelerations, braking and cornering loads are generated. All of the work we do on the suspension is just to make sure the tires are happy - to make them stay flat, to always keep them in contact with the road, and to make sure loads are distributed as evenly to all 4 patches as possible.

So with this car being based in TTC class with a 7 point penalty, that leaves us with only 12 points to work with (19 class points - 7 penalty). And while that gives us some options for lots of different mods (upgrading power, brakes, suspension, lightening the weight, aero and tires), we're going to burn almost all of our points on the tires. This is a very critical decision, so let me explain what we're doing. This decision was made after hours of internal debate, hundreds of permutations of width + compound (+ other non-tire mods), but mostly comes from years of racing experience and knowledge: Knowing that the tires are almost all that matter.

TIRE WIDTH - As I pointed out in a previous post, everything you modify in the TT letter classes is either listed as a No Points Modification (which we are using every one we can!) or is assigned a number of points. It is all clearly stated in the TT rules. Tire width changes are "expensive", and the points in sizes increases above the "base class size" (TTC = 255mm) are shown below.
  • Equal to or greater than: 10mm +1, 20mm +4, 30mm +7, 40mm +10, 50mm +13, 60mm +16, 70mm +19, 80mm +22, 90mm +25, 100mm +28, 110mm +31, 120mm +34, etc.
  • Equal to or less than: -10mm -1, -20mm -4, -30mm -7, -40mm -10,

Big Wheels Keep On Turning!

As you can see you can get points BACK by going to a SMALLER tire as well. There is no other way in TT-Letter classes to gain points back, so this a big deal - and something we are going to do. Many will be surprised by this, as I've preached "BIGGER IS BETTER" for so many years. And while that is still true, we just don't have the points to go bigger, and feel that burning the points ALL on the compound makes more sense. Here's a comment from a corner-carvers reader and my reply:


Originally Posted by Nick C (Post 1059672)
Will the rules let you put 335's on? 17x12" rims are a bolt on affair.


Yes, it would is technically "legal" to run 335mm tires on a C4, but unfortunately the points just aren't there to do this and stay in TTC class. We're going to be running much narrower tires than that, but with what we feel is the right compound.


These pictures are of Jason McCall's 1989 Corvette that is prepped for SCCA BSP class (and was the National Championship winning car in 2005). It runs 17x11" CCW wheels in front and 17x12" wheels out back with Hoosier A6s in 315mm up front and 335mm out back. The fit is pretty tight - it has custom flared front "fenders" (the hood) and has the little 1996 Grand Sport "export" flares out back to make these fit - and we can legally add flares for zero points.


I've driven and ridden in this car and it is a GRIP MACHINE, just a big go-kart. Very fun, and the wide, sticky autocross compound tires he runs are why its so fast. And while I'd love to do this on our C4, the points for the compound (Hoosier A6 = +17 points and A7 = +22 points!) plus the increase in tire width (255->335 = +80mm = +22 points) would cost a whopping +44 points for just this tire upgrade. Using all of the points we have in TTC (19 - 7 = 12) and then even moving up to TTB (+20 more) we're still short by 12 points for a 335mm A7, so that tire choice would be a move straight to TT3. This is why we cannot use the tires we'd LIKE to use (I'd slap 335mm Hoosier A7 tires on this in an instant if the points allowed it!) but the compromise we have chosen will still work well enough - we suspect. Remember: Everything in racing is a compromise... and everything depends on everything else.

http://vorshlag.smugmug.com/photos/i...-qC2jLVb-S.jpg http://vorshlag.smugmug.com/photos/i...-pVBwHrp-S.jpg

Many of you that have experience with the C4 Corvette know that most of the later C4s came with a 275/40/17 tire on 17x9.5" wheels at all four corners, as did our 1992 Base Trim Model Corvette. But the TTC class "base tire" is 255mm, no matter what the OEMs put on the car. Wheel width is unrestricted, other than a track width change limit of +4 inches. Beyond that you take points. Our car has 285/40/17 old and crusty street tires on it right now, which would cost us (+30mm over 255) +7 points to use, but they are a joke. So hard they can spin freely through the first 3 gears. I won't be caught dead on a road course with old street tires, not even brand new 120-200 treadwear street tires (which are worth +2 points), unless the rules require that for everyone.

After racing our TT3 car in various "street tire" events/series last year, and at some tracks we also ran with R-compound Hoosier A6s in other series, I know the true lap time value of sticky R-compound tires. Going from a 335mm BFGoodrich Rival to a 345mm Hoosier A6 is worth a MASSIVE amount of time. On a typical 2 minute road course that difference is 5-7+ seconds per lap with the Hoosier over a 200 treadwear tire, and the Hoosier is MUCH easier to drive. So we're gonna stick with what we KNOW works and that has a great NASA TT contingency program: Hoosier.

TIRE COMPOUND - The compound of the tire is as important than width in Time Trial. Maybe even more important. Why? Because every TT lap is essentially run at a Qualifying lap pace, where you need to be pushing 10/10ths. To win you just need to set ONE fast lap per day (each day is a new competition), and waiting around for 3-4 laps for your "tires to warm up" will only get you mired up in traffic, as the front of the field catches the back end. There are a LOT of tire compounds listed and points assigned for each. The only "free" tire compound in TT-letter are those over 200 UTQG treadwear numbers. The tire models are grouped together with compound and performance parity, and the points given look to be pretty fair. There were massive adjustments made to these points for 2015, which was long overdue.
  • DOT-approved R-compound tires: BFG R1S, Goodyear Eagle RS AC (autocross), Hankook Z214 (C90 & C91 compound only), Hoosier A7, Hoosier Wet DOT (if used in dry conditions—see section 5.6) +22
  • DOT-approved R-compound tires: Hoosier A6 +17
  • DOT-approved R-compound tires and those with a UTQG treadwear rating of 40 or less not listed otherwise in these rules: BFG R1, Goodyear Eagle RS, Hankook Z214 (C71, C70, C51, C50), Hoosier R6 & R7 & SM7, Kumho V710 (note: Continental Tire Sportscar Challenge EC-Dry tires OK (225, 245, 275) +10
  • DOT-approved R-compound tires: Toyo Proxes RR, Hankook TD +7
  • DOT-approved R-compound tires and those with a UTQG treadwear rating of 50 to 130: Maxxis RC-1 (ex. Kumho V700, Michelin Pilot Sport Cup, Nitto NT01, Pirelli PZero Corsa, Toyo R888, Toyo RA-1, Yokahama A048, etc.) +6
  • (non-R-compound) tires with a UTQG treadwear rating of 120-200 (examples: BFG g-Force Rival, Bridgestone Potenza RE070, Dunlop Direzza Sport Z1 Star Spec, Hankook R-S3, Kumho Ecsta XS, Toyo R1R, Yokohama Advan A046 & Neova AD08,) +2
  • Non-DOT-approved racing slicks +30

That is a dizzying array of compound choices and, when combined with the size choices, it makes for a lot of possibilities. But we've run the numbers using these compounds + various widths and have settled upon: 245/40/17 Hoosier R7. Not the softest tire but damned close. Not the widest tire but "wide enough" (and it gives us a point back). The tire choices are still very limited in the brand new Hoosier A7/R7 compounds, but this seems to fit the bill. The spec's on this particular 245mm tire look pretty dang good, and I'm hearing good things about the R7 compound in tests. Our first event will teach us a lot... either we guessed right or made a big mistake!

http://vorshlag.smugmug.com/photos/i...-6vVdxVx-S.jpg http://vorshlag.smugmug.com/photos/i...-8MkHzpL-S.jpg
These wheels are stupid light! We will weigh the wheels alone once the old 275 Hoosiers that came on them are dismounted

WHEELS - We will run these Hoosiers initially on some 17x9.5" SSR wheels, which are both light and strong. Very light, in fact... around 15 pounds. Getting a set of these Corvette sized SSRs is like finding a wild unicorn - very rare and no longer made. SSR went out of business after the 2008 recession but it seems that they have reformed and are back - but not making a lot of the "big" sizes that fit Corvettes any longer. This set came from our shop manager Brad's former Super Stock 1994 Corvette, and he has two identical sets in perfect shape. I have dibs one set but the other is available. The Hoosier A6s on these wheels are DOT stamped from 2008! These wheels are perfect and have been sitting in his attic for almost 7 years.

What's Next

I could go on. And on. But I have probably bored you enough! Our crew is still busy at work finishing the prep on the Corvette for the first race and I'll try to do a quick update next week, right before we head down to MSR Houston Jan 16th. There's still a lot to do and not much time left...


twoquack 01-10-2015 06:34 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Love the bibliography references! Too funny.

Fair! 01-16-2015 11:51 AM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for January 16th, 2015: The first stage of "initial race prep" is completed and I'm going to try to write a QUICK update before we load up and I head down to Houston (in the next few minutes!) for the first NASA Texas event of 2015. We had a lot of parts delays but the crew at Vorshlag got everything on the "MUST HAVE" list completed. They only worked on this car over an 8 day period - due to other cars on the schedule. Big thanks go out to Olof, Ryan, Brad and Jon for all their hard work and long hours over the past week and a half. Thanks also to Jason and Tim for helping pick the mods and source the parts we used. Now all I have to do is drive the thing well... but I have a good back-up driver in Brian Matteucci, thankfully.

Brake Upgrade

The last week was a blur, as we had a lot going on in the shop with other customer cars, the phone rings off the hook in January (everyone waits until now to order parts for the new race season), and we're still gearing up for our new CNC machines - which has been a royal PITA. I had a birthday this week, and tons of other crap going on, and I usually work seven days a week playing catch-up on Vorshlag stuff on the weekends. But last weekend I stole a day away to swap on the front brakes.

http://vorshlag.smugmug.com/Projects...DSC_5523-S.jpg http://vorshlag.smugmug.com/photos/i...-4z5zTJr-S.jpg http://vorshlag.smugmug.com/photos/i...-ftdSNMt-S.jpg
Left: The 12" front brakes are adequate but can be upgraded to 13" rotors "for free" (no points). Right: The two rotors in question

So the 1992-1995 "Base Trim Model" Corvettes all came with these wimpy looking front brakes, shown above. These include the 12.0" diameter x .810" thick vented rotor and PBR twin piston aluminum caliper, which I detailed a bit in my Dec 29th build thread post (post #5 for most of the forums). And I hinted that we would be able to upgrade from the 12" to the 13" rotor set-up for "no points". Normally this is a +2 upgrade, and we only have 3 total points left to play with. I'm saving those for later so we pulled the trigger on the correct rotors, calipers and caliper brackets back on Dec 23rd.

http://vorshlag.smugmug.com/Projects...DSC_5528-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5530-S.jpg

The measured weights for the two front rotor sizes were pretty close to the spec sheets from Centric. Since nobody seems to want to work the last 2 weeks of a year in the USA, we didn't see these parts until late last week (around Jan 9th), and I started installing them on Saturday the 10th. The right front set-up went on fine, but I got bogged down cleaning the front suspension and wheel well...


It was worth it seeing the beautiful, forged aluminum uprights and control arms after 45 minutes of brake cleaner and WD-40 plus some elbow grease got 24 years of gunk and grease build-up off of the metal. Be careful with brake parts cleaner as it is pretty aggressive, but it cuts through the thick caked on grease well. Once I started to see metal underneath I switched to WD-40, and used WD-40 only on all of the plastics and rubber seals. Decades of road dirt wipes off after a little soak with WD.

http://vorshlag.smugmug.com/Projects...DSC_5543-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5544-S.jpg

Cleaning the gunk showed me a split ball joint boot, which we will replace in another round up upgrades later (along with all of the original, crusty rubber suspension bushings - which can be replaced with any non-metal bushings). The old bits came off easily enough and the new 13" rotor and longer caliper bracket went on. And yes, we gained a solid 7 pounds in the rotor upgrade, but its "good" weight. This is cast iron that can both soak up brake heat and more rotor area and vanes to help radiate brake heat. This car will be 3203 pounds with driver and ballast and that's a lot of mass to slow down for thin little 12" brakes at both ends.

http://vorshlag.smugmug.com/Projects...DSC_5537-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5538-S.jpg

The 2-piston sliding PBR calipers (3.56 pounds) are familiar to me, as I've used them on SN95 Mustang Cobras and 3rd gen 1LE/B4C Camaros in the past, as well as on my 94 Corvette - which had the Z07 package and these larger "J55" option 13" front brakes. The J55 calipers are wider, and the J55 caliper bracket (2.56 pounds) is longer, but neither is much heavier than the "base" brake parts.

How are we getting to use the "bigger" J55 brakes from the Z51/Z07/ZR1/GrandSport models without points? Well the trick is this: all 1996 Corvettes models came with the larger J55 brakes, including the base trim model. And the listing for the car we have (1992 Corvette) is listed as 1992-96 Corvette (non ZR1, non-LT4). So we're updating to the base trim level brakes for the 1996 model car, since the 1992-96 cars are listed on the same line (again, not the 1996 LT4 or Grand Sport). We can also play around with swaybars and springs from the 1996 base trim model cars, which we might do later. Here's the rule that makes it all happen...

Rule 8.5, page 41 of the TT ruleset for 2015:

Updating of parts between different model years of the same vehicle model is legal provided that the competing vehicle is both in the same model group listing (same line) in the Table in 8.2.2, and in the same generation of that vehicle model, and that the entire assembly is replaced. Backdating of parts between different model years of the same vehicle model is legal provided that the competing vehicle is both in the same generation and is in the same or higher base class. No interchange of parts between assemblies is permitted in order to create a new assembly.

http://vorshlag.smugmug.com/Projects...DSC_5588-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5545-S.jpg

Just like in SCCA Solo, this "update/backdate" rule can be exploited to your advantage. It takes a lot of research and sometimes rummaging in junkyards, but it is there as a tool for dedicated racers to use. It helps to have factory manuals as well, which we do (thanks to Matteucci).

Again, this is a simple bolt-on upgrade and we have to use OEM (or OEM equivalent) parts to make it legal. No 2-piece rotors, no aftermarket calipers, this is all real deal GM bits. The brackets are from GM and the calipers are rebuilt GM calipers. So getting the right front corner swapped to the J55 bits took less than half an hour. I added blue loctite to the caliper bracket bolts, torqued it all to spec, re-used the old brake hoses (we will make stainless lines when we have time) with new crush washers, installed new caliper retaining pin and E-clip, easy.


Then a friend stopped by the shop mid-day Saturday and convinced me to go see the Interview at the Alamo Draft House. The movie was hilarious and I'm glad I went, but it put me behind on the right front brakes. No worries, I'll do it Sunday.... nope! Amy made me go write the eBay ad for our TT3 prepped 2011 Mustang, which I did then started writing the massive OUSCI 2014 write-up, which I finished today and promptly deleted (it was too harsh).

http://vorshlag.smugmug.com/Projects...DSC_5558-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5557-S.jpg

So on Monday I came in and the guys were working on other items on the Corvette, so I got to work on the left front brake upgrade. As soon as I tried to put the left front caliper on, DOH! It didn't fit.


The box had the correct J55 caliper bracket (which moves the caliper out for the 1" larger diameter) but the wrong caliper casting. It was too narrow by almost .300" and would never fit over the thicker rotor (.300" thicker). Crap. We had ordered the right parts, and the part number on the box from Centric was correct, it just had the wrong damned part in it. Oh well, stuff happens. We took these pictures, sent them to Centric, let them kno how urgently we needed the right part, and hoped for the best.

http://vorshlag.smugmug.com/Projects...DSC_5377-M.jpg http://vorshlag.smugmug.com/Projects...4_145027-M.jpg
Left: original Delco/Bilstein dampers. Right: New Bilstein OEM replacements went on

Luckily they got the right caliper to us just in the nick of time (Wednesday the 14th!). The OEM replacement shocks also arrived at the same time (also ordered in December and also very very late) and Olof and Brad got all of that installed when I was out running errands that day. We replaced factory base trim model "Delco Bilstein" dampers with the OEM replacement Bilsteins that were listed in our Bilstein dealer catalog. The two original rears were blown and the new bits matched up perfectly. These are non-adjustable and are considered replacement OEM dampers available, so they are a "zero point" install.


We re-used the Carbotech brake pads Matteucci had purchased for the OEM brakes, which were XP12 front and XP8 rear. A little soft for my tastes but they were brand new so we will use them for this first event. We pushed some Motul RBF600 through the lines and it felt good. Too many other fires to put out to get to brake cooling this time around so we'll keep an eye on the fluid and Alcon temp strips at this first event.

Tires and Wheels Installed

The Hoosiers arrived this week Olof dismounted the 7 year old crusty 275/40/17 A6 Hoosiers that were on Brad's 17x9.5" SSR wheels. Then he mounted the 245/40/17 Hoosier R7 tires and balanced them. They did all that while I was at lunch one day and I didn't get to weigh the wheels without any tires, so I'll have to do that next time, but I can do simple math. Just weighed an old 275 Hoosier that was removed (22.40 pounds) and the weight of the wheels+old tires (38.76 pounds) that puts the 17x9.5" ET55 SSR wheels at about 16.4 pounds each. Not too shabby.


The SSR wheels were a bit dirty so I cleaned 7 year old brake dust off of the inside barrel and spokes with more WD-40 and some elbow grease. The 245 R7 looks so tiny to me, after a season of using 345 A6 Hoosiers, but it doesn't look bad on the car.

http://vorshlag.smugmug.com/Projects...DSC_5547-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5563-S.jpg

We will see if burning 10 of our 13 class "mod points" on tire compound was worth it this weekend. This is an experiment that could pay off big or fail miserably.

Roll Bar, Harness, Seat and Fire Bottle Installed

With only 8 days of shop time we were not able to build a full roll cage (that will be a 3 week job by itself) but Olof did manage to get the roll bar built, reinforced, and mounted.


A big time suck on this job was making the aluminum cover plates. These are necessary on a fiberglass bodied car to cover the access holes in the body to the steel frame.

http://vorshlag.smugmug.com/Projects...DSC_5573-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5560-S.jpg

Again, on a traditional steel bodied/unibody chassis car this step is not necessary at all. But its a Corvette, and has to be a pain int he ass. Olof used card stock to make templates (below) that cover the access holes, then transferred this into .065" thick 3003 aluminum sheet.


The sheet was cut, bent and welded at the joints to make a box-like shape that fit the funky fiberglass tub shape and covered the openings with about a 1/2" overlap. Then a few holes were cut to add small stainless steel button head bolts and riv-nuts were added to the fiberglass (these are special ones we use just for fiberglass, with a different grip length than normal sheet metal riv-nuts)

http://vorshlag.smugmug.com/Projects...DSC_5559-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5561-S.jpg

A silicone bead was added to the perimeters of the fiberglass and these four, somewhat elaborate aluminum covers were then set in place and bolted down. These will now keep water, dirt and debris from spraying up from the tires and getting into the passenger cabin. Olof did a superb job and they look great and fit tight around the roll bare tubes. These can be removed and the roll bar unbolted for when we go back and finish the roll cage. Similar plates will be needed up front at the additional 2 lower points of the 6-point cage design.

http://vorshlag.smugmug.com/Projects...DSC_5571-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5581-S.jpg

We knew we were going to be WAY too light for the class minimum (3203 pounds) and would need anywhere from 90-200 pounds of ballast. On Tuesday we were getting a little tight on time so I asked Ryan to step away from a cage job he was working on and make the ballast weight bracket from some heavy 1x2" tubing. I was thinking of something basic but he made this beefy assembly with a slick, threaded top cap that fits over a 2" tube.

http://vorshlag.smugmug.com/Projects...3_133846-S.jpg http://vorshlag.smugmug.com/Projects...3_122701-S.jpg

For ballast I purchased new 45 pound "olympic" style barbell plates with a 2" center hole. Typically cast steel weights like this cost around $1/pound, which is what I saw at a few places like WalMart. But after doing some shopping I found the best price at Academy sports, who had a wider assortment of better looking plates to choose from. These 45 pound plates were $31 each, or about $.68/pound. Sure, you can slum around on CraigsList and maybe find some mis-matched weights for around $.50/pound used, but its very hit or miss. Save yourself some hassles and go to Academy. If you want something more compact you can usually buy lead for $1/pound at plumbing supply stores, but just wear a mask when cutting or grinding on this stuff.


I didn't get any detail shots but the factory seat mounting studs (which are reinforced and rated for carrying up to 300 pound passengers) were used with some BIG bolts cut down on the lathe (and drilled/tapped to fit over the seat studs) go down from the top to secure the rack in place. You could pick the car up from this set-up and the 2" tube fits tight to the plates in sheer. At a minimum we will run 90 pounds of ballast here plus 120 pounds of fuel in the 20 gallon tank. Once we replace the 46 pound glass rear hatch with plexiglass we will add another 45 pound plate to the ballast box.

continued below

Fair! 01-16-2015 11:55 AM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

http://vorshlag.smugmug.com/Projects...DSC_5574-S.jpg http://vorshlag.smugmug.com/Projects...B61G3586-S.jpg

The factory seat mounts are reinforced with extra steel from the factory, but we added more. 1/8" thick steel plate wraps around the stock stuff and was stitch welded to the floor as well as wrapped around up into the tunnel and frame on the sides, where it is bolted or welded for more support. The harness anchors for the lap and anti-sub belts are from G-force. These eyelets allow the clip-in ends from a Cobra/Schroth 6-point Profi-2 harness to attach. These are my favorite harnesses and made by Schorth in Germany to FIA specs. This set has 2" upper shoulder straps to better work with he NecksGen HANS device I will be wearing this weekend.


As usual, any "pretty" pictures you see here were shot by shop manager Brad with his Canon gear. The rest of the pics are from my "potato-cam" Galaxy S4 camera phone or my Nikon D90, which I can't seem to use worth a damn. The shoulder harnesses were wrapped around the harness bar tube with the proper wrap technique as specified in the diagram on page 42 of the NASA CCR.

http://vorshlag.smugmug.com/Projects...DSC_3510-S.jpg http://vorshlag.smugmug.com/Projects...B61G3603-S.jpg

Last but not least, a 2.5 pound fire extinguisher was added. This is a small "Halotron" (Halon replacement) hand held fire bottle that can be used to put out small electrical, oil or grass fires and doesn't leave a big mess of dry chemical or foam residue behind. We add these things to every track build possible, even when they have a full fire "system" with multiple nozzles. No need to blow a big bottle when all you have is a little grass fire under the car after pulling off track into dry grass. We used the Drake quick release mount here, which we have used a half dozen times. CNC aluminum, roll bar or floor mounting with the same kit, and one pin can be pulled for fast bottle removal but it stays tight and rattle free when racing. Good stuff.

Weight Check!

Now you've seen how crazy I am about dropping weight and weighing everything in this and other build threads. Weight is the enemy! Lowering weight helps all acceleration vectors, be it braking, forward acceleration or lateral acceleration (cornering). We do a LOT to lower the weight on any race car build, and this car has gone from about 3300 pounds stock (we never weighed this car with the interior but that's what my 1994 Corvette weighed) down to about 2720 pounds. This weight drop was from lighter wheels, no interior, no passenger seat no side or rear glass, and no HVAC bits. The air conditioning compressor has been removed as have the headlights. The lighter wheels and tires help, too.

http://vorshlag.smugmug.com/Projects..._ballast-S.jpg http://vorshlag.smugmug.com/Projects...t_driver-S.jpg
Left: 2841 pounds with fuel but no driver or ballast. Right: 3200 with driver, fuel and ballast

We have added about 60 pounds in the roll bar and about 120 pounds of fuel (its nearly full) and the heavier J55 brakes and it was sitting at 2841 pounds. That's a solid 700 pounds lighter than our TT3 Mustang was without ballast or driver! Sadly we have to weigh 3203 pounds with driver (or else we have to burn points to run lighter), so ballast went back in in the above right picture to get us there. The plexiglass hatch should help remove about 30-35 pounds out of the 46 pound OEM glass, but it might not arrive in time, so we will save that 3rd 45 pound plate for then.

Classing Sheets, Dyno Test and Custom Tune

So we haven't built "letter" class car for NASA TT or PT before, but have helped a number of people class their cars. The base classing + mod points thing is nothing new to us. Just like TT# (numbered) classes, the TTx (letter) classes have an adjusted power to weight ratio. In TT3 the class has a 9:1 ratio but we were able to get ours to 8.8:1 with the adjustments. Likewise, TTC's base 12:0 pounds per horsepower limit has some adjustments as well, namely with a smaller tire...


Using the 245mm tire has had so many benefits and this is just one more - we get a 0.8 ratio bump for this small tire. That might not seem like a lot, but when you are at 3203 pounds it is nearly 20 extra horsepower allowed...
  • 3203 pounds / 12 = 266.9 whp (267 rounded up, in favor of the driver)
  • 3203/11.2 = 285.98 whp (286 rounded up, in favor of the driver)

Which is a good thing, as it was going to be hard to only make 267 whp even with a dead stock engine, manifolds, cats and muffler. We had the car over at True Street Motorsports yesterday and they were able to coax 284 whp and 331 wtq out of this 24 year old, bone stock iron block LT1, through the stock cats, manifolds and exhaust. Not too shabby. It even sounds better after the tune.

Above: Video of the stock LT1 motor at idle and revving, after the dyno test.

We have our dyno plot and classing sheet attached below. As you can see we've started with TTC + 7 penalty points, which left us with 12 points to play with. We got one back for running 245mm tires (-10mm below base class tire) for 13 points total. We burned 10 on the Hoosier R7 and still have 3 points to play with. We will be very stingy how we spend those this season, so stay tuned to see what we invest these points in to make Danger Zone faster.

http://vorshlag.smugmug.com/Racing-E...%20Sheet-S.jpg http://vorshlag.smugmug.com/Projects...y%20Form-S.jpg
Left: The SAE corrected dyno plot making 284 whp. Right: TTC classing sheet with points

Last Minute Tweaks and Fluids

The Moroso oil pan for this motor is huge and the motor now holds 8.5 quarts of Mobil 1 synthetic oil (15W50 is my preferred weight for track cars), with a fresh Wix oil filter. Olof went over the car and filled out a NASA tech form but we still need to get a Logbook issued for the car at the event, so the plan is to leave Dallas early and make the 4.5 hour trek to south Houston on Firday and get there before dark. Then I can set-up the trailer, unhook, unload the C4, get the logbook tech and weighing, and make sure we have our ballast set correctly.

http://vorshlag.smugmug.com/Projects...DSC_5585-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5589-S.jpg

I couldn't leave the massive openings in the hood where the pop-up headlights used to be so I asked Olof to make some aluminum brackets to bolt to the inner hood structure and to the existing holes in the headlight covers. Those went on and now forms a fairly seamless clamshell hood surface. The front turn signal and corner light assemblies were also reinstalled to fill holes. We will go back and make flush mounted aluminum covers later, when we have the time.

http://vorshlag.smugmug.com/Projects...DSC_5586-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5592-S.jpg

Brad jumped into the Danger Zone this week as well and did a lot of wiring and some light fab work to the Corvette. He used to race a C4 himself and knows the car all too well. The wired AMB transponder from our TT3 car was moved to the C4 and Brad made some brackets for that, wired it up to a lighted switch (sometimes its handy to turn off the transponder - if we want to make another entry in the same car with the 2nd battery powered transponder we have). He also got the rear brake lights to work, after repairing some cut wires.


He made an aluminum panel to mount the switch in the center dash area as well as the 3-port "power panel" shown above. This was a cheap Amazon.com purchase which arrived in only a few days for $31 shipped. This panel has waterproof covers over a 12 Volt cigarette lighter port, a volt meter and a stack with dual 5 Volt USB ports (one a high amp and the other a low amp draw - see detail image above). Very slick little package that should prove handy when it powers my onboard vidcam and AiM SOLO timer. I will report back with how well this worked, or not.

http://vorshlag.smugmug.com/Projects...DSC_5594-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5599-S.jpg

The formed, lightweight, plexiglass rear hatch we ordered a week and a half ago arrived this morning so there's no time to fit it, so we reinstalled the OEM back glass. Order Desk Manager Jon wrapped the "ugly" mis-matched door with white vinyl. He also designed, cut and mounted graphics for our logos, "DANGER ZONE", Hoosier and Bilstein decals, and some class/number decals for all sides of the car.

http://vorshlag.smugmug.com/Projects...DSC_5596-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5597-S.jpg

Its time to load up so I didn't get the final pics... tune in next week for the post race update to see the final look, or look for it on Facebook with this hashtag #DANGERZONE.

What's Next?

The only thing on my RADAR right now, outside of cutting metal next week on our new CNC machines (tooling is FINALLY here!), is the race this weekend at MSR Houston. I will be paddocked with Costas, Matt White and other friends probably near Turns 16-17.

http://vorshlag.smugmug.com/Racing-E...IMG_2369-S.jpg http://vorshlag.smugmug.com/Racing-E...n%202013-S.jpg

We are running MSR-H in the Clockwise direction this time (they alternate the direction for NASA events every other year), so I haven't run this track layout since 2013. The video above shows the lap record I managed in the TT3 car 2 years ago, on the skinny 315 tires. The lap record for TTC is currently a 1:50 but I think we might be able to manage a 1:46 if everything manages to stay together on the car...


We have a pretty crazy class lined up: Our 92 Corvette, a 2003 Mini Cooper S (fully race prepped) and a 2005 Mazda RX8 (fully race prepped). Talk about an odd mix... and we will once again be the heaviest yet most powerful car in class, just like we were in TT3. I will post up more details after this weekends race. Until then...


Fair! 01-26-2015 11:34 AM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for January 26th, 2015: Our first race for Project DangerZone has passed and this is my "post-race report" along with some analysis of what went right and wrong.

I Need To Apologize for Trash Talking? Really?

Before I get into our first event results or talk about what we're doing to this car next I think I need to address some of my "pre-race performance speculation", aka: TRASH TALKING. Some say it was unnecessary or disrespectful, but it was done mostly in jest. Getting people to notice our projects takes some extra effort when its a 24 year old ghetto jet, so I took a gamble and "bench raced" my way to some predicted wins and track records. Where's the harm in that?

This was how the car looked right before we loaded up to tow to Houston, sans NASA decals

This sport isn't an "everyone gets a trophy" kind of competition. There are winners and there are losers - that's kind of the whole point. Sure, racing is still fun when you lose, but winning is more funner. Since when do racers need to apologize for a little harmless trash talking? To those that were offended by any of that in my previous posts, all I have to say is "that's part of racing". If I chose to I talk up this project a bit and had it flopped the first time out, I would have looked like an idiot and had to eat some crow. That was the risk on my part, but this whole build is a calculated risk...

The Gamble: An Old Car And A New Tire

Building this 24 year old car into my primary race car for 2015 is a big risk, as it didn't really fit into the "typical cars we work on here". I've picked the wrong horse a few times but normally we can look at a rule book and class listings and see several underdogs that have unseen potential.


But honestly, this car isn't magic. We could have picked a number of other low cost cars that could do very well in this class (TTC), like an E36 M3 or an S2000, both of which are proven winners in TTC at the highest levels. The point of this build wasn't to find the End All Be All car, but to show that as long as the classing is equal the car you choose doesn't matter as much as how it is prepped and driven.

http://vorshlag.smugmug.com/Vorshlag...SC_0231a-S.jpg http://vorshlag.smugmug.com/Vorshlag...SC_0341b-S.jpg

Am I saying the class could be won with any of these cars? Yes, I am. This 1992 Corvette isn't some super ringer, and we've prepped/won with both S2000s and M3s in this very class, with our own cars and customers' builds. Anyone can win if they start with a fairly classed car, prep the car to the limits of the class, test their set-up to maximize performance, use the best tires available (*tires are the biggest factor in any build!) and drive it well.


Another reason why we chose this car (other than it was a sweet deal that fell into my lap at the perfect time) was to show some variety for our business here at Vorshlag. We have unfortunately become "known" for BMWs and Mustangs and Subarus, but the reality is we work on anything that can be classed for road course, autocross, rally or other racing uses: new and old, Domestic, Asian, and German, you name it. People didn't "know us" for Corvettes but we have owned, raced and worked on a lot of them, and use the drive trains from Corvettes in a number of V8 swaps for all sorts of chassis. Having owned this same model Corvette in the past I knew it has potential to handle, brake and accelerate well. To me this C4 was a fairly safe bet, but the fact that it was a 24 year old car made for the biggest gamble. Any number of "old-car" things could have failed at the first event and shut down the weekend before the car ever turned a lap.

http://vorshlag.smugmug.com/Projects...DSC_5575-S.jpg http://vorshlag.smugmug.com/Racing-E...8_120911-S.jpg
Left: The R7 tires were new when we got to the event. Right: After a race weekend with 5 sessions and 3 drivers - tires look great!

The tire was another unknown - the Hoosier R7 was relatively new and we had zero experience with it (I ran the 2013-14 seasons on the A6 in much larger sizes). We also chose to go with a narrow tire width (since there weren't many R7 sizes to choose from yet, as more sizes are being rolled out as the R6 sells out of inventory). Would a 3200 pound car be able to survive on a 245mm tire? It was another gamble. If the tire didn't hold up, we would have to revisit our choices.

http://vorshlag.smugmug.com/Racing-E...DSC_2543-S.jpg http://vorshlag.smugmug.com/Racing-E...6_094849-S.jpg

Some folks sent me links to this build thread discussed online and apparently a few racers were upset that a "big money shop" was coming into the "grassroots" TT letter classes and bringing a purpose built race car against their TT cars they drive to the track. To them I say: the NASA TT rules don't have any wording about this set of classes being for daily driven cars, and in fact the TT division shares the same rules as NASA Performance Tuning - which is for wheel to wheel racing cars - just without the safety regs. We already see PT cars running in TT all the time, because the contingency is good and the PTB-PTF classes are direct crossovers to the TTB-TTF classes. The same holds true for TTU/1/2/3 and SU/ST1/2/3. Time Trial is a haven for race cars but also allows cars without full safety gear to enter.

http://vorshlag.smugmug.com/Projects...DSC_5367-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5362-S.jpg

As for this being a "big money build", that is hilarious and absolutely not what we have done here. This was a last minute option, "Plan B", eight day long race car build - that isn't finished. We had no other car ready for 2015 season, this deal fell into my lap, from a friend who I had brain stormed this car build with three years earlier, and I took this gamble - to have something to race. We have about $5000 dollars in parts/car purchase and about 60 hours of shop work (we log all jobs to the 1/100th of an hour) in this build so far. We worked on this car between regular customer jobs and only spent 8 days actually working on it, but it held together for the first race weekend (barely). We spent our time almost completely on the safety aspects the car needed and left everything else stock for this first event.

If the "speculative talk" in my first few posts here have people fired up to come join us in TTC - that's good! I'm hoping people look at how little money this car costs to buy and prep, how it has proven itself already, and "get the bug" to build a car for NASA Time Trial letter classes or Performance Tuning! This set of classes allows a lot of freedom to choose what you want want to concentrate on: suspension, tires, horsepower, aero. The rules are structured to limit your overall mods which in turn does limit your spending. Its a great series and I encourage people to look at the TT rules/PT rulesets, check out the car "base classing", and start hitting CraigsList looking for something fun to start with. It doesn't need to be a brand new car or an expensive car - look at the past and see how some of the best cars from the last 2-3 decades are classed.

As you may remember, I had proclaimed we could win TTC with this car its first time out, reset the lap record, and even predicted some bold lap times for our first event at MSR-H (1:46 clockwise). So, how did it all play out at our first NASA race weekend? Do I look like a stooge talking out of my hat, or was our guess work correct and did we prep the car in the limited time available in the right areas?

NASA at MSR-Houston, Jan 17-18th, 2015 - The Debut Event!

The old TTC lap record was a 1:50 here was set in 2013, which I showed in my last post on the Friday before the race. I had predicted a lap time of 1:46 but had privately hoped for a 1:45 lap. Let's back up to where I left off in my last post and get caught up on this debut weekend of racing for Project #DANGERZONE.

Friday January 16th, 2015 - Unloading and Tech

After Jon finished installing the decals and I fired off my pre-race forum post, we loaded the trailer and I left Dallas a little late, at about 12 noon - wanted to leave at 10 am. Took me a little over 5 hours to tow 300 miles to the south end of Houston, where MSR-H is located. Google maps has gotten better of late and it re-routed me around 3 construction zones or crashes, on a goofy route, but I never had to stop. It would re-route me on the fly, ask me to verify, then I'd go... which was nice. I got to the track at about 5:30 pm, at dusk, and Costas had a paddock area set-up with his trailer plus both of Matt's trailers. It was pretty far from grid so we did a lot of walking back and forth all weekend. We squeezed my trailer in near Turn 17 and I unloaded the Corvette and rushed to tech as the sun dropped.

http://vorshlag.smugmug.com/Racing-E...6_172019-S.jpg http://vorshlag.smugmug.com/Racing-E...7_110923-S.jpg

The tech guys got me in fairly quickly, right as it was getting dark, and they went over the car with a fine toothed comb. The only thing they could find were the side post battery terminals were uncovered... now normally I'd agree that a top post battery ALWAYS needs plastic around the terminals in case something gets dropped on them, but these were buried on the side and covered by the fiberglass body. Some duct tape and I was legal for this event. I will add the rubber terminal covers soon.

http://vorshlag.smugmug.com/Racing-E...7_161030-S.jpg http://vorshlag.smugmug.com/Racing-E...8_122640-S.jpg

Any time you have a new car teched for NASA Club Racing classes or NASA Time Trial for the first time you have to get a NASA Log Book and a NASA annual tech sticker. The log book cost me $20 and the annual tech decal cost me $10. From here on it would only need the annual $10 decal, as the Log book is good for the life of the car. We're working with NASA to be able to issue log books here at Vorshlag, which should happen soon.

They didn't have the scales set-up Friday night, due to a mix-up with the ramps, so I left the ballast in the car a bit on the heavy side (about 25 pounds over by my calculation) and figured I would weigh the car in the morning before we went out on track. Nobody likes to get a surprise weighing and end up underweight, so I ALWAYS try to weigh the car at the track on Friday or Saturday to make sure our scale numbers match up with their scales.

Reloaded the car back in the trailer, said hi to everyone hanging out, and shared half of a pizza, which I scarfed down on my way to Matteucci's at 7 pm. Crashed out at his place and dreamed of this track layout all night...

Saturday January 17th, 2015 - Race Day 1

I hastily made the TT map (below) for Motorsports Ranch Houston (MSR-H) right before leaving town Friday, which shows not only the track layout and direction we'd be running this weekend but also two special cues for the TT group. First is the "Bunch Up" line, which is between Turns T7 and T6. On the out lap in each session TT drivers can drive somewhat erratically to scrub tires and warm brakes from Pit Out to this line. When cars approach the Bunch Up line they need to quit screwing around and form a single file line with tight spacing. This is done to keep the field from getting spread out and hopefully prevent the front of the field from catching the tail.


The second line to note for the out lap is the "Go Green" line, where the leader of the pack should get up to speed, this time so the field isn't bunched up too tight going into the first braking zone. Starting to go green too LATE only keeps the field bunched up on the first hot lap, usually making that lap slower than it should be for everyone. The TT field should be gridded fastest to slowest, in that order, and this order changes all weekend if a driver goes faster (but not if they go slower).

We had our TT meeting at 8 am Saturday right before our first TT session, called "TT Warm Up" scheduled at 8:45 am Saturday morning. In the meeting we met all the new TT drivers, talked about safety aspects, and went over two areas that will be policed as "out of bounds" and counted as a 4 off if the driver is caught with 4 wheels past outside curbing in two spots that are paved beyond the track limits. Its a long story but there's a shortcut going CW at Turn 1 if you drive inside a curb and knock over the cones they have there to separate the Pit In lane. Another area is between T16 and T17. Each Race Director (RD) makes these decisions and declares out of bounds for each Race Group. Our RD for Time Trial is Richard Wootten.

http://vorshlag.smugmug.com/Racing-E...DSC_6127-S.jpg http://vorshlag.smugmug.com/Racing-E...DSC_5898-S.jpg

Saturday's "TT Warm Up" is a unique TT session for the entire weekend. We grid ourselves by guesswork (since nobody has any lap times yet) and then the times from this session are what are used to grid the field for the first "real" TT session, TT session 1. Times from the TT warm up do not count for competition, but gridding well is important. Lastly, Saturday counts as a separate competition from Sunday, and each day we have 3-5 sessions to get our best single lap time in. The goal is to have the best lap time in class, and a first place finish in a given day nets you 100 points for the regional championship. Hopefully you win your class with enough competitors entered to score contingencies. The only one I care about is tires: to win Hoosiers you need 5 in class per day to score 2 tires for 1st place. With 7 in class they will additionally pay 1 tire to 2nd place. That's assuming the 1st and 2nd place drivers are signed up ahead of time with the Hoosier contingency program, and run Hoosier tires and decals all weekend.

http://vorshlag.smugmug.com/Racing-E...7_091916-S.jpg http://vorshlag.smugmug.com/Projects...B61G3572-S.jpg
Left: The R7 looks good after the first session. Right: The hope is to buy the first set and win 4 more each weekend...?

I got to grid fairly early at Warm Up and slotted in about 8th in line, behind Alan Page's TTB prepped E46 M3. Alan is a customer we know from previous work we've done to his car and he's also fast, with several wins and track records to his name. He was shooting for the TTB track record, set 2 years prior by another E46 TTB racer KenO. A lot has changed in the last 2 years, both to the prep level of cars in NASA Texas as well as the track and that day's conditions. Two years ago was COLD yet all of the old MSR-Houston CW records were set that year. We felt like many TT records would fall at this event, especially the TTC record of 1:50.534.

Video of first laps ever in DANGERZONE - the Saturday TT Warm Up session

If you watch the video above you will see me learning to drive this car while taking it easy on a new set-up. Before that session I had never driven the car more than 100 feet. I guess I know MSR-H fairly well, having driven it maybe 5 previous weekends in the past 6-7 years, but its by no means an easy track. It is also run in both directions and the two courses are quite different, and I think I've done this config 2 or 3 times. The 2.38 mile course was run ClockWise this weekend.

http://vorshlag.smugmug.com/Racing-E...DSC_5966-S.jpg http://vorshlag.smugmug.com/Racing-E...DSC_6208-S.jpg

So I went out in the Warm-up and tried to follow Allan's TTB E46 M3, who had been there testing on Friday and was dialed in. He was also wearing his fancy newly painted helmet livery! He was on a sticker set of 245mm Hoosier R7s so I figured our grip levels would be similar, but his power-to-weight ratio should exceed ours so he'd probably pull away from me - which he did. Luckily I gridded early and got ahead of most of the field, including the other three TTC cars.

continued below

Fair! 01-26-2015 12:17 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

http://vorshlag.smugmug.com/Racing-E...DSC_6155-S.jpg http://vorshlag.smugmug.com/Racing-E...7_122842-S.jpg

The other TTC cars included BJ Mayer's 2003 Mini Cooper S, from Clown Shoe Motorsports, above. This was his beefed, up daily driven, TTC car's debut. It has a better power to weight ratio due to the 205mm tire he runs (>245mm tire = +0.8 ) as well as it being FWD (+1.0), for an unadjusted ratio of (12.0 - 0.8 - 1.0) of 10.2:1 pounds per whp. This car had GAZ coilovers, Vorshlag camber plates, a header/exhaust, supercharger and engine engine mods to help it make more power. I think his race weight was 2550 pounds or so? He told me but I forgot. He was on the SpecMiata tire, which is a 205mm "SM7" Hoosier (essentially an R7).

http://vorshlag.smugmug.com/Racing-E...DSC_6188-S.jpg http://vorshlag.smugmug.com/Racing-E...7_122701-S.jpg

The TTC regular for the Texas Region was Herberto Ferrer in his 2005 RX8. This car is pretty well prepped and he runs the Hankook R-compound race tire, but I am unsure of the rest of his mods. This is a dedicated race car, though, and he is at almost all of the NASA Texas events running TTC. We also had Bryan Leinart who brought his CMC 4th gen Camaro into TTC for two sessions (Warm up and TT session 1) on Saturday and Sunday.

The ugly side of the Corvette. We're working on it.

I took my first two laps pretty easy in the TT Warm-up and tried to follow Allan, as planned. I was still feeling out the car, shift points, brakes, and tires when I botched a downshift going from 5th to 4th into the Courusel, T2, on hot lap 2. Instead of grabbing 4th as I had hoped it went into 6th, but I didn't realize that for a few hundred yards. The motor made all sorts of grumbling noises and had ZERO power. I coasted for about 400 yards around the long 270° corner dubbed the Carousel (Turn 1) and even past the start finish line. I had seen a 1:49 on predictive timing flash by on that lap, but with the long period of coasting it made for only a 1:50.692 lap. I finally figured out what happened by T17, downshifted into 3rd and set-up for another hot lap. Then I caught the back of the field pretty quickly and started smelling some oil smoke, so I came in early.

What I had found when I went into 6th was what the engine tuner warned me about - there's a massive dead spot in the engine between 2000-2200 rpms. Nothing happens - it makes no power. This makes the car drive poorly at these low RPMs, as when you hit 2000 it wants to die. So I made a note to keep the revs above that range, even on the warm-up and cool down laps, and it didn't happen again all weekend. Kind of freaked me out when it happened, though. "Old car stuff"... probably a worn out sensor or something, but the 1992-only engine computer is really limited and hard to diagnose issues with.

http://vorshlag.smugmug.com/Racing-E...7_092551-M.jpg http://vorshlag.smugmug.com/Racing-E...7_092542-S.jpg

Once I came in I went back to my paddock spot and Matteucci and I looked at the smoking issue. Just as he had warned me it was the rear main seal leaking. He had already replaced the RMS once, so I figured it had to be something else. After power washing the bottom of the car to clean all the oil residue off, it never leaked another drop when idling at the shop... but after a few hot laps on track it was clearly a leaking RMS. After we let the car cool for 20 minutes with the hood up we moved the car to get it in the air, and the oil spot (see above) was the extent of the puddle. Not much, about the size of my hand, but every drop that leaks out while driving on course hits the exhaust 4 inches away and made for a SMOKE screen. Luckily this only started after two hot laps.

Times from TT Warm-up - I was in 4th out of 4 in TTC!

I thought we would be sitting up front of the class, even with the 1:50 time, but that was wrong - I was in LAST PLACE out of 4, ouch! I quickly got some text messages from people who weren't at the event asking me why I was so slow, hehe. It's easy to armchair quarterback something when you are hundreds of miles away. The fastest TTC car was the CMC Camaro (1:48.069), followed by BJ's Mini (1:49.768 lap), then Herberto's RX8 (1:50.324) then my coasting time of 1:50.692 bringing up the rear. I suspect my first session times may have lulled some folks into thinking we'd be eating dust all day, but I honestly wasn't worried. Much.


So Matteucci and I got the car in the air on two jack stands and I crawled underneath to clean off the accumulation of engine oil, which wasn't much. A bit of brake parts cleaning and some blue shop paper towel and it was spotless underneath after 5 minutes. It wouldn't drip once the engine cooled off, but this was also wasn't something we could properly fix track side. The RMS repair would require removing the transmission, clutch and flywheel back at the shop. Once all that is out we could then assess the issue and probably install a "seal saver kit" for what is likely a ring scored around the back of the crank.

We went over the rest of the car and it all looked great - including tire wear (perfect) and oil level (still totally full). Brakes felt a little spongy but not enough to bleed yet. Warm tire pressures were 34-35 psi, which is right where the Hoosier A7/R7 "Tire Care Tips" article said to shoot for. After I noted that I had a bit of syncho "snick" going onto 5th gear, Brian adjusted the clutch pedal travel stop that he built, moving it a hair to allow for more clutch dis-engagement. These 3-plate clutches are tricky to set-up and a bit of a chore in the pits... I stalled it a few times until I got the hang of it. The release range is VERY narrow and with almost no flywheel mass the motor has less momentum - making it easy to stall at low speeds. But once at speed? Oh, yea it was worth it! You actually have to shift pretty quickly to allow the revs to match, otherwise the engine slows down too much and lurches even on upshifts.

http://vorshlag.smugmug.com/Racing-E...7_160106-S.jpg http://vorshlag.smugmug.com/Racing-E...8_101121-S.jpg

After checking multiple times that day the NASA scales were still not operational and we were told they would be down for the rest of the day. Knowing that we could have pulled all the ballast out but that would have been a douche move, so we left it all in and even topped the fuel tank off after each session, to keep the tank full and to count on the 120 pounds of fuel ballast. Limiting our runs to 2 hot laps, plus the out- and in-laps, the car was using 1.5 gallons of 93 octane gasoline per session. This was good to know since we were using extra fuel as ballast. I always wanted to be ready if the scales suddenly became operational - weighing under your declared minimum weight (3203) will DSQ the times from the session you just ran, as does a 4-wheel off or spin on course.

Matteucci was signed off for his TT license, since he had extensive SCCA club racing experience. Our "tactical plan" at the start of the day was that I would drive the first two sessions and he would drive the last two. But with the oil leak he declined to drive at all, and I changed my own plans to only take one or two hot laps per session, thereafter. The weather during the warm-up session was cold and I knew the track would get quicker once the sun beat down on the asphalt a bit, so I got geared up for the second TT session of the day, "TT Session 1", which I had hoped would also be my last for Saturday.

http://vorshlag.smugmug.com/Racing-E...DSC_6135-S.jpg http://vorshlag.smugmug.com/Racing-E...DSC_6134-S.jpg
Just part of the 32 car Saturday TT grid, lined up for session 2

I was 12th on grid, right behind BJ's Mini, and was anxious to knock out a better lap. I still felt that the 1:46 lap I predicted was possible, I just needed to put it together and avoid any mistakes. I left a pretty big gap to BJ on the out-lap and didn't do any tire scrubbing. The R7s don't need any warming on this car, and they just work. I really REALLY like this compound and I am glad we made this choice. They wear well and grip was well past 1.2g lateral, in the data logging. Dyson Pham had something like 22 heat cycles on his R7s and still won TT3 on Sunday.

Went out and the first lap was a 1:47 and gobbling up the gap to BJ pretty hard. I went ahead and took a second hot lap and finally nailed the speed into and out of the big Carousel, which plays a big part in any lap at MSR-H. The speedo was showing 110 mph at the "Launch" (T13-14), 119 mph entering T6 on the back straight, and 113 mph entering the Carousel (T2) and 86 mph though that crucial turn. When I saw the AiM SOLO show my second lap at a 1:44.956 I knew that had reset the old lap record by nearly 6 seconds, so I took a cool down and came in.... with the biggest smile on my face in months. :D

Saturday TT Results: http://timingscoring.drivenasa.com/N...ston/Saturday/

After seeing the times from that session I noted that our car was the 7th quickest TT car out of 32 entrants so far. But then I noticed we only had 4 in class, so I went looking for a TT driver and instructor who hadn't run TT yet that day. Once you declare a class you have to stay there for the rest of the day. An old college friend Chris Ramey had been having fun in his TT1 Corvette on street tires, running in HPDE4 that morning, and jumped at the chance to take a ride into the #DANGERZONE! Ramey owns 4 Corvettes at the moment, including a C6 Z06, a C5 Z06, an '87 Z51 C4 and a Callaway Twin Turbo C4. Our TTC prepped C4 would be one of the slowest cars he had driven in a while, heh.

http://vorshlag.smugmug.com/Racing-E...7_142830-S.jpg http://vorshlag.smugmug.com/Racing-E...DSC_6132-S.jpg

After getting the car reset to drive (jack up, clean oil, etc) and adding his registration as 192 TTC, attaching my second (battery powered) AMB transponder to the car and switched off the primary AMB, we had our 5th unique TTC entry. He strapped into the car and asked me what the target lap was. I knew Chris would be fast, and he has a tendency to go "Faster than you'd expect" so I told him to run a 1:46 lap. And asked him to only take one lap, due to the smoke. He got to grid for the 3rd TT session of the day and promptly put in a 1:46.165 time on his first and only lap, watching the AiM SOLO predictive timer closely. Normally I'd have told him to go for broke but he wasn't signed up with Hoosier contingency and I was, so we held him back... Chris told me he felt a 1:43 was possible. Yikes!
End of day Saturday TT Results - #DANGERZONE takes P1 and P2!

The rest of the TTC class didn't get much faster and the sun went behind the clouds right after that session, which cooled the track down. I felt fairly confident that the times would slow down in the 4th session and we sat out the last chance to put in a lap that day. That always makes me nervous but the cooler temps did indeed slow everyone down and my one timed hot lap for the day was enough to win the class, and Ramey's handicapped lap was still good enough for 2nd. BJ and Herberto got quicker after the Warm-Up and beat the fastest entry from that session, the CMC Camaro of Leinart, and every single TTC entry that day clobbered the old class track record.

The TTC win with 5 entries netted us 2 tires from Hoosier and 100 points for the regional championship. The Mini's time was still pretty close to Ramey's but about 1.4 seconds back from my time, so we were definitely keeping an eye on the Mini and the RX8 for Sunday. Anything could happen tomorrow, which was a whole new race.

http://vorshlag.smugmug.com/Racing-E...7_164303-S.jpg http://vorshlag.smugmug.com/Racing-E...7_164339-S.jpg

After Ramey's lap was done we got the car cooled off, up on jack stands, cleaned up the oil residue again, then bled the brakes (in the strange order you are supposed to on a C4) with some RBF600 and rotated the tires. We didn't need to do that last bit, but it didn't hurt and took no extra work. Chris had complained of a long brake pedal and he was right - the pedal felt like mush. Bleeding it didn't help much so it was something we'd have to keep an eye on all weekend and address back at the shop. The fluid looked perfect and the 4 corner bleed produced zero bubbles. Hmm. Matteucci found some RTV and pookie'd up the bottom of the bellhousing, hopefully slowing down the smoke - he was covered in black RTV when he was done, though.

http://vorshlag.smugmug.com/Racing-E...DSC_5923-S.jpg http://vorshlag.smugmug.com/Racing-E...7_180401-S.jpg
Left: The smoke looked like this after 2 laps, time to come in or risk a black flag. Right: Sunset Saturday at MSR-H

Very happy with the first result considering how little we did to the car. The tire wear was phenomenal even with only -2° front/-2.5° rear camber. Toe was 1/8" out up front and 1/8" toe in rear - Matteucci had strung the car himself and we left the alignment alone. The 34-35 psi pressures worked perfectly. The car was neutral if a bit loose, which is just how I like it. The brakes were far from perfect but replacing the 24 year old rubber brake lines might make a huge improvement, as would some real brake cooling (there just wasn't time).

The regular Saturday NASA party was great, with excellent bar-b-q and beer, trophies for the class winners, and pictures for the NASA newsletter. Dozens of people asked about the build and were amazed at the 1:44 lap time,and we had dozens more stop by the paddock both days wanting to see the car and admitting that they followed this build thread. After we had our fill of food we went back to the VERY dark paddock to load the car in the trailer... the trailer door was blocked. Hmm, car has no windows and I couldn't find anyone. After we left I texted Paul Costas and he added a blanket to the car to keep moisture/dew out - which we dubbed his "woobie". It looked hilarious the next morning, for sure.

Sunday January 18th, 2015 - Race Day 2

http://vorshlag.smugmug.com/Racing-E...8_072947-S.jpg http://vorshlag.smugmug.com/Racing-E...8_083233-S.jpg
Costas' woobie kept project #DANGERZONE warm and dry, hehehe

Matteucci was going to work on his C5 Z06 all day so I was on my own for Sunday, but Jaaon Toth planned to help me with the car in the paddock, plus he took a bunch of pics with my camera. I got to the track by 7:30 am, had tons of time, so I ran down to Buc-cee's and got breakfast burritos for everyone in our paddock area, a giant bag of ice for the coolers and filled up the F-350 with diesel. Was back by 8 am with the first session scheduled for 8:50 am.

http://vorshlag.smugmug.com/Racing-E...DSC_6174-S.jpg http://vorshlag.smugmug.com/Racing-E...DSC_6243-S.jpg
Left: TT3 racer Joshua Garcia brought his Toyota 1UZ V8 swapped AE86 and had a blast. Right: An E46 330Ci which used to be mine

Figuring the first session would be cold again, and still needing an extra TTC entry, I asked TT driver/instructor Jason Toth to take the first session in the Corvette as TTC 192. Since Sunday and Saturday are separate races, using the same number as Ramey did the day before isn't a conflict. We strapped the extra transponder back on and he got to grid for the chilly first session. I was again hoping the same cars from Saturday would enter and give us five in TTC so the winner would get two tires, whoever that might be.

continued below

Fair! 01-26-2015 12:18 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

Jason's lap was a bit compromised due to a TT3 car that spun right in front of him on his first and only hot lap, shown above. He backed off but drove through the smoke and took a sedate lap, putting one in the books and keeping out of trouble. He said he felt a bit rusty and jumping into a strange car with such a crazy clutch was a challenge. I appreciate the effort and it would probably only take a few laps for him to be right there on times, as I've raced with him for many years.

http://vorshlag.smugmug.com/Racing-E...DSC_6216-S.jpg http://vorshlag.smugmug.com/Racing-E...DSC_6220-S.jpg

As the temps rose it started to smoke and it was dripping a bit when Toth went to the scales. The tech guys wanted to see the car again before we went back out so I took the car back to paddock, did the raise/clean/reseal trick after the car had cooled off. Once it was back to tech it wasn't leaking a drop and they cleared me for laps once again.

At this point I wanted to only take one lap and head home. A headache was starting (probably from sniffing brake parts cleaner for two days!) and looking at the weather it seemed that session 2 on Sunday might be the "golden session" where the best lap times of the weekend would end up. Got up to 70 degrees in the afternoon but was still low 60s for session 2.

Allan Page had run a 1:41.013 for a new TTB record in the morning but he also felt like session 2 would be faster. We weren't scheduled to go out until after 11 am, so we had a long break to reset the car. Meanwhile the sun did come out and warmed up the track. I got the transponders swapped back, got my suit and gear on, and went to grid sitting in P8 overall for this session, ahead of the rest of the TTC field and even some TT3 cars.

I was going to be putting in ONE hot lap, for the day, and it needed to be as perfect as possible. The goal was to go fast enough to ensure no other entries could touch the lap time for the rest of the day, so I could leave early with a little confidence. Ramey had predicted a 1:43 the day before but with the spongy brakes I wasn't sure. After frantically searching I realized that BJ had left Saturday night, apparently with a broken exhaust header. That left us with just 4 in class - Oh well, whoever won TTC today wasn't going to win any Hoosiers.


In the video above from this session you can see that the front of the field was really slow to take the green flag on the out lap and it bunched up the whole field badly on the straight before the Carousel. I was behind Dyson's TTB S2000 (running light and racing in TT3 for the day, trying to beat my old TT3 lap record and win that class). I wasn't sure about his power levels or times, other than he was gridded ahead of me so he had to be running quicker. Still, I backed off a bit on the run up to the Carousel.

Sunday TT Results: http://timingscoring.drivenasa.com/N...ouston/Sunday/

I had talked with the TT3 driver gridded behind me, telling him I was going to be taking ONE hot lap than I'd get out of his way. But he saw me back off of the S2000 on the out lap and passed me. Technically we're not supposed to pass on the out lap (double yellow) but it wasn't a big deal... other than I had to back off a lot into that turn before we began the hot lap. I tried to gap him enough to avoid this, but as we took the start/finish I was gaining on him and had to brake early into T17. Crap, I figured my lap was ruined, but then he nearly spun off track in T16. He had some spin issues that weekend and I was ready for that. Once he got it straightened up he was way off line and I snuck inside him with a clean pass and got on with my lap. I probably lost only a half second there, at worst.


That lap was great and the car felt hooked up everywhere. I still had plenty of driving mistakes like early braking into "the Launch" and probably the T6 corner off the back straight as well, but it was still my quickest lap of the weekend. As I came around for the start/finish on this first hot lap I felt like it would match Saturday's time but instead it was a solid 1.2 seconds faster with a 1:43.733. Booya! Thinking the pass slowed me down I took a second lap but it was slower at a 1:44.3. I didn't try to push my luck with a black flag for smoke so I backed off after that and came into the pits. Wootten was watching and sent me to the scales, warning me that this entry was under "special scrutiny" from the National level and if I was light my times would get bounced (which is normal).

http://vorshlag.smugmug.com/Racing-E...8_104105-S.jpg http://vorshlag.smugmug.com/Racing-E...DSC_6246-S.jpg
Before my session (at left) and afterwards (at right) in Impound, where I was scaled

I wasn't worried and just as expected I was 25 pounds over our minimum weight of 3203 pounds at 3228. That's exactly what I was shooting for - a big, safe margin of 25 pounds for this first event. For my first time to scales all weekend I was damned happy that our weighing and ballast had been perfectly in line on our scales as on NASA's. With constant fuel top offs after each session, this means we can run a good 15 pounds lighter next time (I'll always leave a 10 pound safety buffer over our minimum weight, at least).

http://vorshlag.smugmug.com/Racing-E...8_120855-S.jpg http://vorshlag.smugmug.com/Racing-E...7_160120-S.jpg

After I got back to paddock and changed into my street clothes I let the car cool down and then looked at the results and decided to skip the last two sessions. I still had that pounding headache and a 5 hour drive home to look forward to, so I started loading up the trailer. When the car was cool enough I drove it inside (which itself was a huge win!) and strapped it down, then said some goodbyes and hit the road. With a pair of wins, a track record reset by 7 seconds, two tires won on Saturday (only 4 in class Sunday means no tires were available), 200 points towards the class for the regional championship, and knowing that I was able to back up the smack talk. Whew, what a relief!


Allan ran his best lap of the weekend in his E46 M3 and reset the TTB record to a 1:40.805, which was almost exactly 3 seconds quicker than my new TTC record. The overall results for that session are here and it looks like we were 7th quickest for the day, out of a total of 38 TT drivers for the weekend (we had several new TT drivers added after Saturday check-rides). I'm very happy with that lap time, and never thought we'd only be two seconds off of our old TT3 lap record in this old heap, but the track was fast that weekend and 6 new TT lap records were set - many of them on the Hoosier R7.

New MSR-H CW lap records set this weekend:
TTE - Team Black Armor - 1:49.525
TTC - Team Vorshlag - 1:43.733
TTB - Allan Page - 1:40.805
TT2 - Bill Woods - 1:38.550
TT1 - Raymund Guerrero - 1:37.114
TTU - Paul Costas - 1:34.301

Only the TTD, TT3 (our's) and TTF records remain unchanged from 2013.

So that was our first race report - probably too detailed and boring for everyone, but I wanted to explain the extra entries/drivers in our car, the challenges we had with the brakes and rear main seal, as well as show some of the competition we're up against. It should be a fun year!

Thanks Go To...

Big thanks to the Vorshlag crew for busting ass and getting the prep done in such a short time frame. Also thanks Matteucci for helping me at the track Saturday and letting me crash at his place both Friday and Saturday nights. He never got to drive the car due to the smoke and I feel bad that he didn't get any seat time. Sucks more because as he has a WRL race at MSR-H soon coming up.

I also need to thank him for the top notch car prep he did on the car for the years before we bought it. Matteucci owned, built and tested this car for three years and did all of the non-safety prep that wasn't detailed in my previous posts here. So much "old part replacement" maintenance, gutting the interior, got the car light, the crazy 3-disc clutch, the oil pan, the new Opti and more. We were damned lucky to get a car this well sorted to start with, as the work he did would have taken months to knock out.

Event picture and video gallery: http://vorshlag.smugmug.com/Racing-E...-MSR-H-011715/

Five years ago Jason and I had seen the potential of this car and wondered why nobody had built one for TTC. When Matteucci wanted to build a TT car two years later I told him about the LT1 C4 in TTC and he jumped on it, found this car for a steal, and did all of this work to get it ready. After doing one RMS he found that it was leaking once again and just didn't want to mess with it - and neither did I, but I wish we had! I foolishly assumed it was something else, but was wrong. Would have been a much more enjoyable weekend without the smoke screen. ;)

What's Next + Remaining 2015 Race Schedule?

These are the remaining Time Trial competition events we want to enter with this car in 2015:
  • February 14-15 - SCCA Club Trials @ TWS
  • March 14-15 - NASA @ MSR-Cresson
  • April 25-26 - NASA @ TWS
  • June 13-14 - NASA @ Hallett Summer Shootout
  • July 31-Aug 2 - NASA @ Laguna Seca - Western States Championships
  • September 4-6 - NASA @ VIR - Eastern States Championships
  • September 26-27 - NASA @ MSR-Houston Counter-Clockwise
  • October 17-18 - NASA @ "TBA" (???)
  • November - NASA @ "TBA" (???)
You may notice that I have removed the USCA and Goodguys events from our season schedule. After some rules changes I strongly disagree with (that were actually aimed at our car), and what I felt was a botched Optima event in Vegas, we won't be trying to sneak Project DangerZone into these "street car" events - even though there are much more gutted, purpose built race cars racing in both. I'm going to give USCA another year to get the bugs worked out in their series before we jump into that circus again. We had only planned to do Goodguys in this car to test for USCA, and without a set of different wheels and 200 treadwear tires, the C4 isn't legal for either series at the moment.

Even though people think all we do here at Vorshlag is "work on Terry's cars" that is not at all the case. We had to squeeze in this prep in between customer jobs or after hours and only had time to do the basic safety prep, the brakes and tires, but just ran out of time to investigate the RMS, upgrade brake lines and fabricate the brake cooling this car obviously needs.

http://vorshlag.smugmug.com/Racing-E...IMG_3219-S.jpg http://vorshlag.smugmug.com/Racing-E...B61G5660-S.jpg
A dedicated track test like this is a MUCH better way to try out a new car BEFORE it is ever run in competition

And while this MSR-H NASA weekend was a great "Test" for us, and it was successful, the RIGHT way to do this would have been to get the car ready WEEKS before any competition event and test the car at a track somewhere, to work out the bugs and see where failures happen. Please don't take this one LUCKY example of us getting a car prepped in 8 days and winning/setting track records as the norm. It is not. Normally this quick-build process sans testing is a guaranteed way to look like a jackass and FAIL. But I'd rather be lucky than good...

The next event on our schedule is the SCCA Club Trials event, which we will likely miss. While I'd love to enter the Feb 17-17th event at TWS, which would be a great way to help that club grow it's PDX/Trials program and to test for NASA at TWS later this year, we're just too booked. We have some V8 swap projects we HAVE to wrap up for customers, plus the CNC machines are finally cutting metal, so Jason and I will be buried building hundreds of bits we need to fulfill backorders. There's no way we can work on #DANGERZONE in the next month so I have it stashed in my trailer for the time being. I will make NASA @ MSR-Cresson, however, and we will HAVE to do the RMS repair before that event.

http://vorshlag.smugmug.com/photos/i...-csJgmX5-S.jpg http://vorshlag.smugmug.com/photos/i...-kbDhKQk-S.jpg

We had talked about swapping the metal-puck triple disc pack for a Kevlar twin disc pack while the trans was out (for the RMS repair) but I kinda like the metal clutch now and I think we'll keep it. Front brake cooling and a new set of BrakeQuip flex lines will be built, for sure. We have found some clever ways to cool the brakes on a customer's C4 and we will employ similar tricks on this TTC build.


I'd like to address the body roll and brake dive this car has (see above), due to the stock swaybars and springs. The OEM replacement Bilstein shocks were also very "floaty" over the launch and anytime we touched a curb. The car handled like stock because it still had all the stock bits, but with 24 years of deterioration in many areas. The OEM rubber suspension bushings are disintegrated but we can replace those with non-metal bushings for zero points and $0 (Matteucci included a full set of poly bushings with the car). We still have 3 points left for mods - what do YOU think we should do with them? Here's a list of possible mods we might use the remaining points in TTC for:
  • Springs +2. This could be aftermarket or OEM springs outside of the BTM 1992-96 Corvette options
  • Swaybars +2. Burning two points would allow us to go with any aftermarket swaybar at both ends, providing its not cockpit adjustable
  • Shocks +3. This is an expensive way to burn three points considering we have stock bars and spring rates
  • Cold Air / Hood Venting +1. This is an unusual mod rule which allows all sorts of holes in the front bumper cover and hood for both cold air intake inlet as well as engine bay venting.
  • Headers +2 points. As much as I'd love to do this its almost impossible to add real headers without taking +1 for moving/removing/replacing the cars and +2 for after-cat exhaust changes. And we're already at the limit for power at this weight.
  • Adding 10mm of tire is +1 and adding 20mm is +3. That's tempting but I felt like we had more than adequate grip and tire wear was very good.

Give us your input - we'd love to hear what you think would make DangerZone faster. Remember: we have a very tight budget for purchasing parts and only 3 points left to play with in TTC. While I'd love to go nuts with an expanded TTB build of this car (and another 20 points of mods), that isn't in the cards this year.

Low Profile Build? Not So Much

This build thread has exceeded my hopes as far as how many people have read it (many thousands). We're posting it on 5 forums now (GRM, NASA Texas, SCCAForums, Corner-Carvers and Vorshlag) and I had probably 50 people talk to me at the NASA event and say they enjoyed reading it. One piece of potential bad news is that we now have some extra scrutiny at the highest level. We heard that the National PT/TT director Greg G has noticed our little build, as well as one other recently built Corvette TTC entry - Dave Schotz. Greg even called our TT director at the track and asked about our car. Uh-oh...


We know Dave from both his owning SCCAforums (one of the places we are posting this build thread) as well as his many previous wins in SCCA and NASA. We found out that he quietly built a 1991 Corvette and ran it in TTC for the first time a week before we ran our car. He told me he has always wondered why nobody built a C4 for this class, and when the tire points changed this year he decided to build one to replace his TTC Camaro (shown above in 2013, when he won THREE national titles in the same week!). With minor race prep and a set of 275mm R6 tires he has already racked up wins and a TTC track record at his first event. I won't say any more than that as Dave is likely to run his car at NASA Nationals West and he doesn't have "public build threads" like we do. If we can, we'll run our car at NASA Nationals East and hopefully NEVER have to run head-to-head with Dave... because he has a LOT of national championships. :D

Unfortunately this car Dave built, and our car if it does well, will probably get the C4 Corvettes a lot of scrutiny at Nationals and if either one does well, it might get these cars re-classed next year. I hope that isn't the case, and I expect that Greg will look at Dave's previous wins in a number of cars as well as the work we're doing before he makes any big changes. This car has been classed in TTC (and even TTD) for 5+ years without any alarm bells going off. Just a fluke that two serious C4 Corvette TTC builds happened to debut one week apart... what can you do? I'm just hoping we can make it through this season without any road blocks or rules changes... I like the car and want to continue developing and racing it for this season.

Until next time,

Fair! 04-09-2015 06:31 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for April 9, 2015: Wow, I started writing this about 3 weeks ago (March 18th) and never finished. I lost the last 3 weeks to our new CNC machines, which I have been manning non-stop 24/7, trying to build a lot of parts to fulfill backorders. Somewhere in the last month - and I'm having trouble remembering back that far - we ran NASA @ MSR-C, and the weekend before that (COTA). We also prepped and took 11 cars to the Optima event March 28-29 at TMS, where I raced a C5 Corvette. Anyway, we took the TTC C4 and our TT3 Mustang to the NASA event, but I will break up the "race report" into another post. Let's look at the prep work that we managed to sneak into the C4 before this latest NASA race. It was a lot of work, but maybe not quite enough...

Roll Cage + Nets + Dash Rework Completed

About 3 weeks before the MSR-Cresson event I pushed the C4 onto Ryan's plate and he took over the front half of the roll cage fabrication plus the remaining safety gear that needed to go into the car before the next event. It took him less than 30 hours to do all of the work below. I wish this could have started sooner but our schedule is always packed and we can only squeeze in work on our shop cars when we get a small gap.

http://vorshlag.smugmug.com/Projects...B61G5233-S.jpg http://vorshlag.smugmug.com/Projects...B61G5258-S.jpg

The "back half" of the cage was built as a bolt-in roll bar, since we ran out of time to fully cage the car before the January event.

http://vorshlag.smugmug.com/Projects...B61G3496-S.jpg http://vorshlag.smugmug.com/Projects...B61G3494-S.jpg

We noted that my helmet was in a tough spot when making the 4-point roll bar in January, and as you can see above, any roof cage structure that was kept inside the window frame would be INSIDE my helmet. As it was the targa structure was touching my helmet - this car is narrow inside, up top. I didn't think me leaning at a list to starboard was the safe way to drive, so we pushed those upper cage tubes outside the window track.

http://vorshlag.smugmug.com/Projects...B61G5325-S.jpg http://vorshlag.smugmug.com/Projects...B61G5352-S.jpg

Will this affect airflow? Maybe. Will this positively effect drag reduction and top end speed? I highly doubt it, and nothing short of wind tunnel testing could prove it either way. Is it safer this way, keeping a piece of 1.75" steel tubing away from my helmet? OF COURSE IT IS. So we did it - its the safest, most common sense routing for this car and this driver. It looks a little odd, but its the right solution - this side of getting a shorter driver. My seat is already touching the floor - which we cannot alter.

http://vorshlag.smugmug.com/Projects...B61G5419-S.jpg http://vorshlag.smugmug.com/Projects...B61G5427-S.jpg

The front, upper cage tube near the windshield surround also follows that contour closely, again - to keep it away from my head. It sits as high up as possible, to prevent the cage from restricting my forward field of view. The unusual angle of the upper tubing junction there was later gusseted with more tubing, shown lower in this thread.


An "FIA" style vertical crush prevention bar is also added, which narrows the side door opening but makes the heavily raked windshield and A-pillar structure much more "pancake" resistant in a crash that put the car on the roof. I would like to keep my head and spine as delivered, thank you very much.

http://vorshlag.smugmug.com/Projects...B61G5444-S.jpg http://vorshlag.smugmug.com/Projects...B61G5542-S.jpg

Note the tight joint fit-up in the above right pic. After this point in the cage build (we missed taking pics of the door bars) pretty much everything was built and tacked in place, then the cage structure was completely pulled out of the car, in sections, to do the final welding.

http://vorshlag.smugmug.com/Projects...B61G5846-S.jpg http://vorshlag.smugmug.com/Projects...B61G5838-S.jpg

Sub-assemblies like the NASCAR-style door bars and load plates (above) were welded on the fab table, for easier access to get to the bottom of tubes. The FIA bar was welded to the A-pillar bar, things like that. Standing on your head to weld upside down inside a car is the suck.

http://vorshlag.smugmug.com/Projects...B61G5874-S.jpg http://vorshlag.smugmug.com/Projects...B61G5881-S.jpg

After the roll bar and cage sections were removed the B-pillar roof hoop was cut out of the car, lickity split. Yes, this was deemed necessary to gain access to the upper tubing joints for welding. The cage structure far exceeded the OEM rollover protection of this piece, and it was welded back in later. Luckily there was a body seam there that covers up the outer fiberglass cut. It won't have to be body worked.


The picture above skips ahead a bit, where the cage is almost fully welded and back in the car, and the roof structure hoop was welded back in place. At this point it is getting close to being done. The upper front corner gusset tubes are shown here, and yes, they do land on the FIA bar. It was another compromise to keep from having to cut a giant chunk of the already weak windshield frame away at the A-pillar. The roof diagonal is also shown in this top-down shot.

http://vorshlag.smugmug.com/Projects...B61G6292-S.jpg http://vorshlag.smugmug.com/Projects...B61G6297-S.jpg

The tubing above ties the front downbars into the firewall at one of the few places that has any metal. This is still a mostly fiberglass car, and the front half of the floor pans, trans tunnel, and most of the firewall is all just thin fiberglass. Can't exactly weld or land metal tubing onto that structure. So Ryan picked the farthest outer edge of firewall, which is metal at the base of the A-pillar, and tied some short pieces of 1.5" tubing from there to the main cage. This is to prevent TIRE INTRUSION into the cabin in a heavy crash, and for a car like this, well worth it. It doesn't pass through the firewall or tie into any major structure there. The upper OEM A-pillars are still free floating, since there is no roof structure (its almost identical to a convertible in this respect). With the OEM targa roof removed and the windshield out, the windshield surround is surprisingly weak and flexible. Oh well... we cannot tie into the A-pillar in any substantial way without taking more performance points for TTC/PTC.

http://vorshlag.smugmug.com/Projects...B61G6427-S.jpg http://vorshlag.smugmug.com/Projects...B61G6430-S.jpg

The door bars are pushed outwards to almost the skin of the fiberglass doors, and the factory impact beams were removed. This is to give a lot of ROOM to the driver's arms, and the extra room is appreciated. These bars have a lot of curves in them, to fit this crazy chassis, so they were tied into the outer frame rails in 2 additional spots, as shown above. This makes them stronger in a side impact, and the bars and frame would both have to deflect a lot to touch my arms. I'm rather fond of my arm and would like to keep it attached to my body.


Another thing the upper side cage bars do is go UPWARDS from the B-pillar joints/factory roof structure hoop, to give me more head room in a rollover. The seat is bolted right down to the floor, without a slider or any risers, to increase headroom. The only other trick left is to lower the floor - which costs performance points in TTC, which we don't have to spare. Everything in racing is a compromise.

Non-Cage Stuff + Safety Upgrades


Our friends from Titan Auto Glass (above) came out to re-install the windshield after the welding was complete. They had already been out a few weeks earlier to remove the new windshield they had installed in January - an added expense of doing the cage in two different time periods, with a race in between. Always, always get the windshield out of the way for a cage job.

http://vorshlag.smugmug.com/Projects...B61G6451-S.jpg http://vorshlag.smugmug.com/Projects...B61G6552-S.jpg

The 14" wide panoramic mirror from Longacre was mounted to fit my driving position. With the driver's side mirror I have an unobstructed rear view. The passenger side door mirror is broken and useless, for now.

continued below

Fair! 04-09-2015 06:31 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

http://vorshlag.smugmug.com/Projects...B61G6275-S.jpg http://vorshlag.smugmug.com/Projects...B61G6313-S.jpg

The targa top was modified to fit around the cage. The metallic structure of the 22.6 pound assembly was removed, leaving just the outer skin. This wasn't ideal but necessary. The skinned plexiglass panel has the right curvature and was mocked up to make sure the windshield frame and B-pillar structure still fit.

http://vorshlag.smugmug.com/Projects...B61G6361-S.jpg http://vorshlag.smugmug.com/Projects...B61G6450-S.jpg

The roof panel mounts shown above were fabricated (and logged under the cage work) and welded to the top of the factory windshield surround and the top of the B-pillar roof structure. On top of each is a poly bushing, machined to the correct angle, bonded to the steel mount, and with a thru-hole for the mounting bolts. Mounting the plexiglass to the cage at only one end could allow the flimsy plexiglass to buckle under load, so the "flexible" OEM roof structure that was left was used instead.

http://vorshlag.smugmug.com/Projects...B61G6565-S.jpg http://vorshlag.smugmug.com/Projects...B61G6563-S.jpg

This plexiglass top mounts with flush mounted stainless bolts in 5 places and keeps the airflow going where it should, but that's about it. The top is still somewhat translucent, which isn't ideal, but it wasn't worth the time to fabricate this complex curved roof panel out of aluminum or even skinning the plexi in vinyl film. Yet.


While adding the cage, it made sense to add the nets and other safety gear required for wheel to wheel racing; this car could be run in PTC (W2W) as well as TTC (Time Trial). A Schroth center net was added first, and it passes through the dashboard surround that we added. As I showed in my first post, this car came to us with just the gauges attached to the fiberglass inner dash structure, but I wanted more of the original dash pad and gauge binnacle installed. It looks more complete and professional, plus provides better anti-glare protection. Ryan managed to save what he could from the old dash pad that came with the C4, clearanced that and the inner structure to clear the roll cage dash bar, and mounted the gauge cluster back in the original binnacle.

http://vorshlag.smugmug.com/Projects...DSC_5367-S.jpg http://vorshlag.smugmug.com/Projects...9_172746-S.jpg
Left: Before, with no dash pad or gauge "binnacle". Right: OEM binnacle added as well as about half the dash pad

A metal panel was added for a section and a toggle switch for the OEM traction control defeat was added. This really needs a momentary on/off push button but this works for now (it simply grounds a circuit) to disable the ASR. The driver's door net was a bit more complicated, as they always are. Ryan made a lower frame that has a slide-thru mount that can slip down and out of the way when unlatched, but gets rigid when the net is latched in place. The upper frame pivots at the back on a spherical, to allow it to swing down and in/out a bit.

http://vorshlag.smugmug.com/Racing-E...5_140504-S.jpg http://vorshlag.smugmug.com/Projects...3_170140-S.jpg

We added padding at the last minute, as the car was being loaded onto the open 2 car trailer - in the rain. I had hoped we would have time to paint the cage/interior at Heritage but we started about a week too late, as our shop schedule was just too overloaded. So we got to this point for safety...

Suspension Upgrade

After the cage work was completed by Ryan, Olof tackled the oil leaks next, starting about 3 days before the race weekend. In my last update I asked folks what they thought we should spend the remaining 3 points in TTC on: springs, shocks, exhaust, etc. We took this input and looked at the (somewhat limited number of) lap data from MSR-H and went ahead and decided: SPRING UPGRADE would be worth 2 of those 3 points.

http://vorshlag.smugmug.com/Projects...B61G6722-S.jpg http://vorshlag.smugmug.com/Projects...B61G6707-S.jpg

This base trim model 1992 C4 has the original FE1/FX3 springs (417 #/in front, 227 #/in rear - with wheel rates that are lower than that) with longer lowering bolts out back. Matteucci had already added the aftermarket shims/tricks to lower the front. It still sits very high up front, too. I was hoping to stick with Hyperco C4 springs at both ends, since we are a dealer, but their mold to make the C4 front spring was damaged last year and it would cost $70K to replace it. So yea, Hyperco is out of the C4 front spring business. I next called Paul at Vansteel and had a good conversation with him. He had better Hyperco data on the C4 than Hyperco, and recommended the Vette Brakes Products (VBP) "Xtreme" front spring, shown below.

http://vorshlag.smugmug.com/Projects...B61G6712-S.jpg http://vorshlag.smugmug.com/Projects...B61G6715-S.jpg

This VBP front spring is different from the OEM C4 style front springs, in that it is flat and has adjustable ends like a C5 front spring. He told me of a number of racers using this successfully and it was the one he used on most C4's like ours (track use). McCall also had good luck with this spring on his 1989 Corvette LT4 he runs in BSP class autocrossing. I've driven that car and it WORKS.

The C4 rear spring mounts with adjustable bolts at the ends, so you can alter ride height stock. Here are the OEM 1992 + 1984 rear springs

So then I called VBP and the guys there helped me narrow in on a spring rate for their front spring - which can be built from 1000-1250 pounds/inch. We decided on 1200 and they custom built a spring for us that measured out at 1170 pounds/in.

http://vorshlag.smugmug.com/Projects...B61G6630-S.jpg http://vorshlag.smugmug.com/Projects...B61G6623-S.jpg

For the rear I had picked up a 1984 Z51 rear spring from Matteucci with the car purchase, and it turns out to be the stiffest OEM spring ever offered on the C4 at 500-510 #/in. That end is easily ride height adjustable with these lowering bolts, which come in various lengths for extreme lowering. We stuck with the ones that Matteucci had and got to the ride height shown below. This is about 3" lower than stock up front and 2.5" out back, which lowers the CG significantly but doesn't get the rear suspension into any funky geometry (going lower can).


In case you were looking at the math, we increased the front spring rate by 2.8 times (417 to 1170 #/in) and the rear by 2.25 times (227 to 510 #/in), which is fairly typical of where we start for most IRS cars. Sometimes we don't go quite as far in the rear as we did here, but our spring choices were limited and I really like a car that "rotates well". I was not disappointed with the handling on track, either.

Oil Leak Fixes!

So our debut with NASA @ MSR-H had very limited laps due to massive smoke from leaks at the Rear Main Seal (RMS) and oil pan gaskets. We were limited to 1-2 lap blasts before the smallish oil leaks started to get on the exhaust and caused smoke. The oil drops stayed off the track - until you stopped, then it would miss the exhaust and drip straight down.

http://vorshlag.smugmug.com/Projects...B61G6630-S.jpg http://vorshlag.smugmug.com/Projects...B61G6623-S.jpg

Matteucci warned me before I bought the car that he thought both the RMS and oil pan gaskets needed to be fixed. He did the clutch job and Moroso oil pan install on jack stands, and it is nearly impossible to do those two things correctly on a C4 without a lift. The big Moroso oil pan has kick-outs for extra oil capacity and trap doors for better oil control while cornering - strongly recommended for LT1 motors on a road course.

http://vorshlag.smugmug.com/Projects...B61G6640-S.jpg http://vorshlag.smugmug.com/Projects...B61G6638-S.jpg

To get to the RMS the transmission has to come out, and that's no small task. Olof spent about 2 days doing this repair + the spring swap above, and it was finished at the last minute - we didn't load up and leave for MSR-C until 5:30 pm Friday (had planned on leaving by 12 noon to get a good spot).

http://vorshlag.smugmug.com/Projects...2_101954-S.jpg http://vorshlag.smugmug.com/Projects...2_102022-S.jpg

The C-channel/torque beam, driveshaft, shifter then trans were removed. Next the complicated QuarterMaster triple disc 7.25" diameter clutch pack and flywheel was removed, then the 3 pound starter flex plate. The weights are shown below.

http://vorshlag.smugmug.com/Projects...B61G6672-S.jpg http://vorshlag.smugmug.com/Projects...B61G6675-S.jpg
This is how you remove over 50 pounds from your flywheel/clutch mass. And this is what makes the motor rev!

We replaced the locking nuts on the clutch pack but put the sintered bronze plates back in, as the wear looked great. We had thought about swapping to their twin disc Kevlar "rally clutch" set-up, which uses the same cage and flywheel. This set-up is supposed to be more forgiving on slow speed driving (paddock, between rally stages) but I have gotten used to the triple disc and we decided to stick it back in since it looked good.

http://vorshlag.smugmug.com/Projects...B61G6649-S.jpg http://vorshlag.smugmug.com/Projects...B61G6657-S.jpg

The oil pan had some NASTY funk in it, which made us all VERY concerned. We found a hole in the intake boot that might have let some dirt past the air filter, but more than likely this is just normal wear. The grit was very fine, grey in color, and magnetic/ferrous, so probably indicative of worn piston rings. Well it made great power a month ago on the dyno, how bad could it be? We didn't have time to do a compression or leak down test, so I had Olof clean out the pan and slip in a fresh FelPro gasket and get it buttoned up. With the car on the lift and two removable subframe members removed it was easier to install it straight and true.

http://vorshlag.smugmug.com/Projects...2_102645-M.jpg http://vorshlag.smugmug.com/Projects...2_164208-M.jpg

We used the $300 LT1-specific RMS installation tool and got the new $10 seal installed square to the crank as well. Both the RMS and oil pan gasket had small rips in them, allowing the oil leak to happen. The exhaust went back on, fresh 15W50 Mobil1 oil and filter went in, and it fired right up. Runs much better with the hole in the intake boot and TPS sensor fixed, it seems.

Yep, the Throttle Position Sensor (TPS) and intake boot were both replaced. The TPS repair removed the dead spot I noticed at about 2200 rpm/light throttle, so that was money well spent. The factory intake boot is unique to the 1992 model year, and is no longer made. The closest thing we could find was the $50 silicone boot from Mid-America Corvettes, which isn't exactly like the (now out of production) stock piece, so we have to (temporarily) take a 1 point hit for Cold Air Modifications. We may or may not revisit that point later.

I updated the classing sheets for both the Corvette and the Mustang while the guys weighed the C4. We picked up about 45 pounds in the front cage structure (1.75" x .095" wall DOM) so they pulled one 45 pound plate out of the ballast box and away we went. We kept the same brakes, tires and other bits on the car from the previous race in January. No time to swap the rear hatch to plexiglass or anything else - go go go!

Time & Parts Budget To Date

I've been promising to show the hours and parts costs from the beginning but I write these posts when I have time and I have been very busy lately, trying to run the business and make CNC machined parts (feed the machines!). I finally stopped long enough to add up some costs. Let's look at hours first...

Hours Spent To Date = 104.94 hours, logged per MyShopAssist

I was guessing close to 100 hours and that was pretty dang close. We log all jobs, both customer work and our internal test mules and race cars. The only work not counted was my hours for installing the front brakes and cleaning the front suspension (about 4) and Jon's hours cutting and installing the decals (about 3). Here's the breakdown:

Round 1 - work before MSR-H
  • Mounting and balancing the R7 tires on the Enkei wheels = 1.02 hours
  • Install OEM replacement Bilstein shocks = 1.35 hours
  • First Oil + Filter Change (8 qts Mobile1 15W50) = .45 hours
  • Caliper + bracket + pin replacement for correct unit = .68 hours
  • 4-point Roll bar fab + cover plates + fire bottle install + floor pan repair + hatch removal/install = 51.23 hours
  • Sub-total before first race = 54.73 hours


Round 2 - work before MSR-C
  • Roll cage completion (front half + roof structure removal/install) = 29.23 hours
  • Ballast mount fabrication + machining = 5.32 hours
  • Oil pan gasket + RMS repair (+ driveshaft, torque arm, trans and clutch R&R and 2nd oil + filter change) = 11.19 hours
  • Front and rear spring installation (including fixing the VBP spring mounts) = 3.97 hours
  • Sub-total before first race = 49.71 hours

As for costs, its still around $5000 total, all-in. I will do a better budgetary break down next time, when I have more time to make the "report" in our accounting software. We lost our Operations Manager and it took me 3 weeks to look for and hire a replacement, who starts on Monday. It has been crazy busy around here and we've been down a man for 2 weeks, ugh.

This Week At Vorshlag - March 12, 2015

The video below shows a good bit of the work Olof tackled with the clutch, springs, and gasket/seal repairs. Its 7 minutes long and also touches on some other fabrication work + some of the CNC work Jason and I have been buried with for weeks.

YouTube video: https://youtu.be/iG3ZQ7gbFbk
SmugMug video: LINK

I've finally set-up our new Vorshlag YouTube channel and will start to post various videos there, as they seem to work better than our SmugMug video hosting (which seems to wreck the videos on mobile devices).


That's all I have for this time.


Fair! 04-23-2015 03:59 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for April 23, 2015: Well the second NASA event in Project #Dangerzone did not go according to plan, but I had a bad feeling about the motor when Olof had the oil pan off and stuck a flash light up into the cylinders. I will cover the March Motorsports Ranch - Cresson event in the C4 below.


We also brought our TT3 prepped Mustang, so if you have read that car's latest build thread update, this NASA @ MSR-C "race report" section is verbatim from the massive four-part April 23rd update there. There is additional information below that race report about what's coming next on DangerZone...

March 14-15 - NASA @ MSR-Cresson. Running the '92 Corvette in TTC + '11 Mustang in TT3

Since we brought and I drove 2 cars for this weekend, this portion below will be shared in both the TT3 Mustang thread and the TTC Corvette thread.

Vorshlag Event Photo Gallery: http://vorshlag.smugmug.com/Racing-E...-MSR-C-031415/

We were pretty far behind on prepping the Corvette, and we saw some issues inside the motor with the oil pan off that worried me a great deal. Luckily I had signed our team entry "Team Vorshlag" up for a double entry with two cars (paid twice). This meant that Amy and I could both drive both cars in TT that weekend. So in case she wasn't winning in TT3, I could hop in the Mustang for a session and give it a go. Or if the Corvette had problems, which I suspected it just might, I could still get some seat time in the Mustang.


We didn't quite get the C4 prepped by the deadline I had hoped for, but our techs only work on Vorshlag owned cars when we have time between customer cars. Since we were slammed we had to squeeze in some time, but it was neither long enough nor soon enough. Since there was no time to track test the C4 after this big round of changes, this event would be the first time running this car with a brand new cage/nets, new spring set-up/ride heights, and then some items were unfinished. There were also some potential problems uncovered when we replaced the leaking rear main seal and oil pan gaskets.

http://vorshlag.smugmug.com/Projects...B61G6630-S.jpg http://vorshlag.smugmug.com/Projects...B61G6638-S.jpg
You can see a lot of the C4 prep in this "This Week At Vorshlag" video from March 12, 2015

Scoring in the bottom of some cylinders was evident. A thick coating of metallic grit was in the bottom of the oil pan, which was magnetic so that meant it was ferrous. Likely this meant we had smoked a piston ring or two (or eight). But when the oil pan and trans were buttoned up, the car ran fine and had no smoke. More importantly, ALL of the oil leaks were gone.

http://vorshlag.smugmug.com/Racing-E...3_170127-S.jpg http://vorshlag.smugmug.com/Racing-E...5_161741-S.jpg

The cage work was rushed and we ended up installing the SFI padding while loading the car onto Mike M's trailer at 5:30 pm, then loaded the TT3 Mustang into our trailer, and left the shop at 6 pm - about 6 hours later than I had hoped. It had been spitting rain all day but the predictions were clear for Sat-Sunday. We knew that this weekend was going to be crowded and both Mike and we were trying to get good paddock spots. Turns out it was a record attendance for ANY event at MSR-C with 220+ entries, many of whom got there early Friday to test, so we were parked in the grass when we arrived Friday evening. This made loading/unloading more difficult and we had to watch the splitter for scrapage on the paddock road, plus hot Hoosiers always got covered in dead grass when we came in off track.


We got Mike's 2012 Mustang and the Corvette unloaded off his open 2 car trailer, then our Mustang unloaded from our trailer right before dark. We then reloaded the Corvette (no side windows) into our enclosed trailer, since it looked like rain might hit over night. Amy, me and Mike unhooked the two trailers and we went to dinner in Granbury at the 1890, best restaurant in town. Amy and I stayed in Granbury at the Hilton Garden Inn, 15 miles from the track but it is worth the drive - not to mention the one hotel in Cresson fills up months in advance for race weekends.

http://vorshlag.smugmug.com/Racing-E...P7B_0472-S.jpg http://vorshlag.smugmug.com/Racing-E...P7B_7444-S.jpg

I'm glad we brought both cars. We got to the track early, then scrambled to get both cars ready without any crew to help (mistake). TT meeting was brief, check tire pressures and fuel levels, then I suited up and climbed into the C4 while Amy got ready in the Mustang. I went to grid and started mid-pack for the "Saturday Practice" session, which doesn't count for TT competition but the times are used to establish grid position. Scrubbed in the used R7 tires from the January event and they felt great. I got into a group with the front cars that quickly pulled away on the first hot lap, with nobody behind as far as I could see.


The C4 felt FAST and the handling was much improved with the new spring rate set-up, but there was a LOT OF SMOKE coming out of the exhaust. I knew it wasn't the RMS or oil pan, and it wasn't leaking oil, but definitely out of the exhaust and only when under power. I took 3/4 of this hot lap at speed and no oil was getting onto the tires so it felt fine, but I knew I'd get a black flag. I feared there was something seriously wrong inside the motor - broken piston ring or ring land? - and excessive blow-by was pumping out through the PCV system, into the intake, burning it in the combustion chamber, then sending it out the exhaust.

http://vorshlag.smugmug.com/Racing-E...P7B_9962-S.jpg http://vorshlag.smugmug.com/Racing-E...P7B_9131-S.jpg

I was driving my own line but watching the mirror for the exhaust smoke and watching the corner workers for black flags, thinking "Not AGAIN!", I lifted for the last 2 corners and coasted into the pit entrance way off the pace. This was somehow still a 1:25 lap, beating the old track record by 2 seconds. Coasting. GRR!

Video of the C4's first "throw-away" lap - which was the fastest it ran all weekend, and 2 sec ahead of the TTC record?!

After the Warm-up session my half-aborted 1:25.097 lap was was 9th fastest overall in TT and I was somehow in the lead over 5 other TTC cars in class, but the next closest car was only 1/2 second back. I knew this was going to be short lived and the time wouldn't stand because it was during the "practice" session.

http://vorshlag.smugmug.com/Racing-E...4_152231-S.jpg http://vorshlag.smugmug.com/Racing-E...4_134902-S.jpg

I figured we could fix the issue and make it back out later that day. After getting fuel (filled up after every session to maintain weight - even through it never got weighed), I came back to paddock and climbed out of the car (wearing the HANs was torturing my back on the way out of the cage each time). Amy pulled up, also in from the session early? She said the engine was cutting out BADLY, just like at COTA.

http://vorshlag.smugmug.com/Racing-E...598478_n-S.jpg http://vorshlag.smugmug.com/Racing-E...928118_n-S.jpg

So great.... now I had two broken cars to fix, when traditionally we have had near perfect performance week after week in the past 4 years. I started to think and remembered two years ago when the Mustang ran poorly at ECR in 2013 - it was a bad Wide Band O2 sensor. The front two O2 sensors are Wide Band and help the engine tune itself as it runs. The after-catalyst O2s just make sure the cats are working and don't do anything to the performance or tune.

http://vorshlag.smugmug.com/Projects...4_092731-S.jpg http://vorshlag.smugmug.com/Projects...5_090207-S.jpg

We had replaced both of these wide band O2 sensors before, but it had been 2+ years. So we changed out of racing suit and gear, started up the F350 and ran into Ft. Worth looking for parts. We rounded up a new Wide Band O2 at Ford Dealer (after trying 3 parts places), paying too much but happy to find it. Then stopped at Wal-Mart to get more Mobil1 for the C4, then at a NAPA on the way to get parts to try to make a remote breather/catch can for it as well.

http://vorshlag.smugmug.com/Racing-E...4_135518-S.jpg http://vorshlag.smugmug.com/Racing-E...4_141241-S.jpg

By the time we had gotten back TT session 1 was underway, but we had work to do. Parked in the grass we drove the Mustang up on the Race Ramps and I changed the O2 sensor, which was a back breaker, but it fixed the issue completely and it has run fine ever since. Initially I had hoped the C4 smoke was maybe a weird stuck PCV issue, so we pulled it out of the system and plumbed the crankcase to a big external breather. Sure enough, short test drives on city streets showed it was smoke free. After lunch on Saturday we took both cars out again, and Amy was fine but the C4 smoke was back, and worse than ever.


Amy was flying away from me as I took a single lap in the C4, immediately smoking. I came through Ricochet sideways at 100 mph, with a tiny bit of oil dripping out of the breather and getting onto the right rear tire. Doesn't take much! I immediately slowed down and pulled off line, waving drivers by. The smoke stopped but I was still getting waving black flags, telling me to come in for a "look". Pretty scary, horrible lap coasting and getting out of everyone's way. Called it quits for the weekend for the Corvette, as there was no fixing it track-side (needs engine internals).

http://vorshlag.smugmug.com/Racing-E...512612_n-S.jpg http://vorshlag.smugmug.com/Racing-E...926786_n-S.jpg
My temporary "breather mod" only made matters worse, so I shut it down after less than a 1/2 lap. "....MEH..."

http://vorshlag.smugmug.com/Racing-E...DSC_7008-S.jpg http://vorshlag.smugmug.com/Racing-E...DSC_7050-S.jpg

Amy went out and got it done, winning the class and two tires for the day. She let me drive a couple of laps in the Mustang in the final TT session at the end of the day, but it wasn't needed, and she won TT3 all on her own Saturday, with just one session driven in anger.

Amy likes using the curbs, eh? I kept calling her "Curby McCurbison", but there was zero damage

We put the Corvette back in the trailer since it looked like it might rain again, which was difficult due to the now lowered ride height of the C4, the angle of our paddock spot and the condition of my back. Lots of wood, ramps and cursing later we got it loaded.

http://vorshlag.smugmug.com/Racing-E...4_201123-S.jpg http://vorshlag.smugmug.com/Racing-E...4_193700-S.jpg

The Saturday night NASA party started at 6pm and we all had some great food and drinks while they handed out trophies, took pictures with the NASA trophy girls, and all that. We also got our 2014 Regional TT3 championship trophy, since we missed the NASA banquet a few weeks earlier due to a different March ice storm (Thanks to Al Gore!)

Sunday we got to the track at 7:30 am. Unloaded the C4 again to make room for people in the trailer that day (great shelter from wind and sun) and we got Amy ready for TT session 1 in the red car. We forgot to refuel after her stint so I went to grid in TT session 2 with less than 1/2 tank, making it fuel starved badly. With the downforce the car makes and speeds in Big Bend and some other corners making for lots of lateral g-loading, we have to run 3/4+ tank of fuel, minimum. I fumbled my way to a 1:19.8, fuel starving for 3 laps.

http://vorshlag.smugmug.com/Racing-E...DSC_7095-S.jpg http://vorshlag.smugmug.com/Racing-E...DSC_7104-S.jpg

After I fueled up the car fully, I went out again in TT session 3 after lunch, when the conditions were a bit worse. I ran a 1:19.1 in two laps before catching traffic, but by then the front tires were DONE and it was pushing badly. These well used front tires were not good enough for two drivers both days, so I was almost 2 seconds off my 2014 pace (on sticker tires). That's rule # 1 in racing: TIRES MATTER MOST!


I had a 1:19.4 on day 1 and got it down to a 1:19.1 on tires beyond "end of life" on day 2, so I guess that's some progress? Amy went out in TT session 4 but the tires were all gone by then and the times were off pace. We loaded up both cars onto both trailers by 5 pm and were on the road home by 5:30, tired but happy to have won the class both days. Amy got her first legitimate TT3 win on Saturday, so she was ecstatic. I was bummed about the C4, and my "practice session" 1:25.0 time (good enough for 2nd by only 2 tenths, and it was an ABORTED lap!) was bounced since it was the lone practice session, so I ended up down in 5th place on Saturday using my "smoking, limping, black flagged lap" in TT session 2 on Saturday, bah.

continued below

Fair! 04-23-2015 04:11 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued below

http://vorshlag.smugmug.com/Racing-E...P7B_7448-S.jpg http://vorshlag.smugmug.com/Racing-E...P7B_3178-S.jpg

So that means no worthwhile points for the TTC entry, but two solid "100 point days" for our TT3 entry, if we end up having the Mustang all season (it's still for sale). Four fresh Hoosier A7s (in the right sizes this time, yay) were won here, so we'll have fresh tires on the Mustang at TWS in April. The original set of 245mm R7s still only have about 8 laps on them in 2 race weekends and look great, so we'll run those on the C4 again at the next event (only won 2 new tires at MSR-H in this car).

So the smoking issue and metal in the oil pan can only mean one thing: the the 24 year old LT1 motor needs to be rebuilt. That's two events in a row smoking and/or leaking oil in the C4, and I don't want to get a reputation for that nonsense. I want the motor rebuilt, back in the car, re-dyno tuned, and a track test day completed before #DangerZone goes back to a NASA event.

http://vorshlag.smugmug.com/Racing-E...IMG_1107-S.jpg http://vorshlag.smugmug.com/Racing-E...569896_n-S.jpg

The Mustang must have been weighed 4 or 5 times all weekend, but it was never close to being underweight. We gained some weight somewhere, as it was always about 70-90 pounds over the 3802 pound minimum all weekend, but I kept taking ballast out until we were closer. The C4 only made two laps, in two sessions, so it never had a chance to get called to scales. It was well over the 3203 pound minimum, as I kept topping off the fuel tank and the added mass of the front cage section was also present.

http://vorshlag.smugmug.com/Racing-E...s3-14-15-M.jpg http://vorshlag.smugmug.com/Racing-E...s3-15-15-M.jpg
Left: Saturday TT Results. Right: Sunday TT Results

Official Results: http://timingscoring.drivenasa.com/N...MSR%20Cresson/

Last up, some in-car video from the Mustang, shown below. This was with a suction-cup mount on the windshield, instead of the roll-bar mounted I/O Port mount usually located behind the driver. I moved that to the C4 and should really just buy another one to keep in the Mustang. It makes for a better view and shows the driver issues (flailing around like I usually am).

In-car video of the TT3 winning lap in the Mustang

The lap timer fell off it's windshield mount, so I was driving "blind" without predictive lap times. I hate that, and never want to drive on track without the predictive timing from the AiM SOLO. That 1:19.1 lap was a solid 1.8 seconds off my 2014 pace here (1:17.310, still the TT3 lap record) in the same car, but that could just be the difference between a sticker set of Hoosiers vs a very old and worn set. It was still enough for the win in TT3 and 4th fastest for the day in TT. We had 6 cars in class on Saturday and 5 cars in TT3 on Sunday. Amy was quick Saturday but was off the pace Sunday, when the front tires fell off. Glad she let me take 2 sessions in the car, because we needed it. Still won by nearly 2 seconds but it would have been a tenth or two short with her late Sunday times.


On the photos - we took pics with our Nikon and my potatocam phone, but thanks to MohFlo photography for the shots they got (bought the digital files) and also to Jason Toth for the images he shot. Their stuff was way better than anything Amy or I took (maybe the one above was OK, which was from my potatocam). And the next time I want to bring to cars to race and DON'T bring any Vorshlag crew to help, somebody kick me in the head? That weekend was a lot of scrambling around, and I'm too old for this crap. ;)

New Motor + Potential Protest?

Apparently my publicly posted forum build thread got somebody fired up and there has been a protest made to the National level, which I am assured that I will lose. It has to do with a few tubes in our roll cage design, which are deemed performance enhancing. Of course we can remove or re-route before the next event, but I am going to appeal the two issues. If we lose that at least we have time to correct this before the next event - where we could have lost points or gained a DSQ. :)

And before some of you call this nit-picking, I'm glad we found out about it before going to NASA Nationals and getting bounced there.

http://vorshlag.smugmug.com/Projects...B61G6294-S.jpg http://vorshlag.smugmug.com/Projects...B61G6427-S.jpg

As for the motor, there are very clear guidelines in the TT rules on what is allowed and what costs points. As usual we will build the next motor to the limit of the rules, within the budgetary constraints we have set, and try not to make any more power - as we are at the limit right now.


I am also trying to round up a factory 1995-95 LT1 wiring harness and computer, which we can legally swap to if we do the swap completely replacing the 1992 EFI system. This newer computer will allow for BETTER TUNING on the motor, as the 1992 is a one-year-only set-up with very small number of EFI parameters that can be altered. Sean at True Street said the 1993 model year was a big jump up (nearly double the parameters) and the 1994-95 has even more things he can tweak. This will hopefully help de-tune any power we might make with a fresh motor as well as allow the engine run smoother. Still, the fresh TPS sensor and repairing the giant leak in the air intake tube already made a MASSIVE improvement in driveability and smoothness under power at MSR-Cresson.

That is what is so strange about the last event - the motor was pulling hard and the car ran strong, other than the massive clouds of smoke coming out of the exhaust. What is it they say? A motor runs best right before it blows up! Well this one didn't scatter, so hopefully the stock crank, block and heads can all be re-used when Erik Koeing at HK Racing Engines gets his hands on this 24 year old longblock. I'll have Olof do a compression check before it comes out (next week) and gets shipped to HK.

What's Next?

There are a lot of events we will be at in the next few months, but the first time we'll likely be able to run the C4 in anger is June at Hallett. And of course I want a dedicated track test that is successful and oil/smoke free before we go there. The shop is slammed right now and I'm trying to squeeze DangerZone on the schedule to have the longblock pulled.

We also need to do some.... test fitting of drivetrain parts... for a customer's upcoming C4 build. This will be the first of its kind, ever built in a C4. Its so crazy I can't even talk about it. Gotta finish his C5 build first, though.
  • April 24-26 - NASA @ TWS
  • May 2 - Cars & Coffee Dallas
  • May 3 - SCCA autocross @ TMS Bus Lot
  • May 9 - Five Star Ford Track Day @ ECR
  • June 13-14 - NASA @ Hallett, "Summer Shootout"
  • August 23 - SCCA Solo at Lone Star Park
  • September 4-6 - NASA @ VIR - Eastern States Championships


Since the C4 is down, we just finished the track prep and loaded the TT3 Mustang in the trailer. Amy and I are about to head down to TWS for the last NASA event ever at this track, this weekend. Its being plowed under soon to make suburbia even more crowded, yay.

Until next time,

Fair! 05-26-2015 12:19 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for May 26th, 2015: Its been pretty busy around Vorshlag and I've been buried in the CNC room, but with a bit of extra help in there for the summer I can finally sneak into my office and write a few project build forum updates.

This Week at Vorshlag for May 8th, 2015 - including a bit on the C4 at the 6:40 mark

We haven't had time to work on the C4 other than extracting the drivetrain. Again, we only work on our "shop cars" when we have a gap in our customer work schedule, which hasn't existed. So I snuck the C4 in line for a few hours of shop time and had the guys yank the motor and it was sent off to be rebuilt. We've also had more conversations about "the internet protest", which was actually FIVE things, and we're aiming to fix all of those before our next event. I will go over some upcoming car prep and document the issues of the protest in great detail.

Motor Rebuild Time


Yep, after 24 hard years this old LT1 has seen better days. Too much crankcase pressure makes for excessive blow-by and smoke, which precludes us from making a lap without a black flag. There's not much to share in this section other than the motor is finally out and shipped to the engine shop, and how that came to be.

http://vorshlag.smugmug.com/Projects...DSC_7776-S.jpg http://vorshlag.smugmug.com/Projects...DSC_7785-S.jpg

With but 6 weeks until our next event, I couldn't wait for an opening in the shop schedule any longer, so I asked Brad and Ryan to get that LT1 out of the car as quickly as possible on May 6th. Within a few hours the drivetrain was out and the motor was on a pallet, ready for truck shipment the next day.

http://vorshlag.smugmug.com/Projects...DSC_7793-S.jpg http://vorshlag.smugmug.com/Projects...DSC_7791-S.jpg

After pulling the driveshaft, c-channel drivetrain brace, transmission and shifter out, they could finally lift the motor out of the engine bay. Its a TIGHT fit in there, with a cross brace right next to the front balancer. Its almost impossible to stab the motor and transmission into the car tied together, unlike in some other cars.

http://vorshlag.smugmug.com/Projects...DSC_7796-S.jpg http://vorshlag.smugmug.com/Projects...DSC_7799-S.jpg
A sharp-eyed reader noticed the "throttle body airfoil" (top right), which we don't have points for. Its coming out.

The motor was stripped down to the basic long block, it was bolted to an engine stand I had built years ago for easy GM V8 transport. Many LS1s have been shipped on this shipping stand, but this is the first LT1. This frame was then bolted/strapped to a pallet, wrapped in plastic, and all 480 pounds was shipped to the guys down at HK Racing Engines in La Grange, Texas. One thing someone on Facebook noticed in a picture I posted (and called me to warn me about, thanks Dave!) when the engine was out was an aftermarket "airfoil" in the throttle body. With a 24 year old car, sometimes a previous owner's mods get missed. No excuses - this airfoil is coming out. We want this car to be PERFECTLY legally. Squeaky clean. As a business owner in motorsports I cannot afford to be caught cheating in competition, and I'd rather lose a race than knowingly break a rule.

http://vorshlag.smugmug.com/Projects...DSC_7804-S.jpg http://vorshlag.smugmug.com/Projects...DSC_7828-S.jpg

HK has pulled the top of the motor apart and told me "it all looked fine". By now they should have some .020" overbore replacement pistons, rings, bearings and valve springs ordered, which should freshen things up a bit. I think they will find some broken piston rings when they tear the bottom end apart, since we noted a lot of scoring in the bottom of a few cylinders as well as "too much" ferrous metal grit in the bottom of the oil pan.

http://vorshlag.smugmug.com/Projects...DSC_7806-S.jpg http://vorshlag.smugmug.com/Projects...DSC_7803-S.jpg
I'm going to clean the living snot out of the engine bay while the motor gets rebuilt

Erik Koenig is a master engine builder, and also a damned good racer. I raced with him for a couple of decades and he knows how to read a rulebook. I sent him the pertinent pages, we discussed what we can do (and what we cannot) in TTC, and he's all over it.

Our TT3 prepped Mustang sold in June 2015

Problem is that I didn't give him a lot of time, so making the June 15th Hallett event is going to be tight... if the motor isn't back in by then I'm NOT racing our TT3 Mustang at Hallett (it is very much for sale!) Yes, this TT3 car has won 4 tires every time we have shown up to a NASA event in the past 2 years, and did so again a few weeks back at TWS - winning by a huge margin after taking only a single lap on Sunday - but that car is out of competition, for me. :( If you know of anyone potentially interested, please send them to this link - Thanks!

No more "back up ride" in the TT3 Mustang, as it still has perfect paint that I want to protect for the next owner!

So, I've already used my "4 drops" in TTC for the regional championship, so if we miss this June Hallett event in #DangerZone I'm just not going to worry about TTC regionally for this year. With our summer break coming, we won't have another NASA Texas event after Hallett before NASA Nationals East, so I will have to go to an out-of-region NASA event or use non-NASA events to test the car before Nationals. I've still not had more than 2 laps in a row in this car all season, dang it.

Changes Planned To Be 100% Legal

I mentioned a couple of the things that I was told were protested against #DangerZone in my last post, but have since seen a more complete list of items in an email from Greg Greenbaum, NASA's National TT director. In private correspondence Greg passed on an alarming number of things that some reader of this build thread wrote in about to protest (five).


As I mentioned before, some are cage issues - three in fact. One was a very picky, gray area issue that I have been "all but told" is allowed on this car, for safety concerns in this narrow cabin. As I showed in a previous post (again, I am hiding nothing) parts of the roof side bars next to my head are a hair outside of the window plane, but otherwise they'd be inside my helmet. I can't sit any lower without going through the floor, either. Its this way or no cage, and after my accident last year I'm not keen on driving un-caged race cars.

http://vorshlag.smugmug.com/Projects...-changes-S.jpg http://vorshlag.smugmug.com/Projects...B61G9085-S.jpg
We always tie in both sides of "NASCAR" door bars to the frame, for symmetry and safety. But in NASA TT-letter classes it is +2 points

The other two cage issues are shown to be illegal in the rules... sort of. First, the passenger side door bars clearly cannot be tied to the frame even though they are allowed on the driver's side (up to 3 places). I read the rule wrong, where it said "drivers-side" I thought "both sides", stupid mistake on my part. It still seems odd that the cage rules would make for an "asymmetrically safe" cage. So our plan of putting a passenger seat in this car and taking riders is out, since we can't make the right side of the cage as safe as the left without taking +2 points (and bumping up a class). Easy fix with a saw and grinder.


The third and most unclear of the cage protest rulings has to do with the two optional tubes that the TT cage rule above states can be added to the firewall or foot well areas. Our two tubes are apparently placed too high to be called "tire intrusion protection" (but the rule says nothing about tire intrusion, of course, that is something you have to assume). What the rules wording does say doesn't match of what the rules makers meant, however, as I'm told after this ruling that it should read as follows:


Originally Posted by what they really meant to write
"Two additional attachment points for either two foot-well bars or two bars to the front firewall BELOW THE TOP OF THE TIRE (one on each side) may be added without TT Modification Point assessment".

http://vorshlag.smugmug.com/Projects...B61G6294-S.jpg http://vorshlag.smugmug.com/Projects...B61G6507-S.jpg

The "below the top of the tire" bit was what I was told is inferred in this rule. Shame on me for not knowing that. The two NASA race directors I showed this cage layout to thought we had them in the optimum place, but they were also wrong. So apparently we have to read and interpret the rules then always ask for a clarification for anything (or risk a DSQ at an event). You were warned: there are the written rules and then there are the unwritten rules. Again, this is an easy fix - We will cut those two tubes out, move them down below the top of the tire, weld them back in place, and then be double-secret legal. :D

http://vorshlag.smugmug.com/Projects...DSC_5522-S.jpg http://vorshlag.smugmug.com/Projects...DSC_5544-S.jpg

Item four brought up in the protest was our upgrade to 1996 Corvette Base Trim Level front 13" disc brakes, over the 1992-95 BTM 12" front discs. Again, we did our homework and found that all 1996 model Corvettes came with the 13" diameter fronts, which used to be an optional upgrade on base coupe Corvettes from 1989-95 under the Z07 or Z51 options. But since this car is listed on the same line as all 1992-1996 Corvettes, non-LT4, non-ZR1, we can "update" to the 1996 base trim brakes for zero points (normally +2). Yes, its a loophole but hundreds of racers look for loopholes to exploit - that's called racing. Luckily the National office agreed with our documentation here and disallowed that particular protest.

Shocking Thing About OEM Shocks

The last issue that is being ruled against (item 5) has to do with the OEM Bilstein vs the replacement Bilstein dampers we used, which I am gonna lose. See, we don't have the points left in our TTC class points budget to add better dampers (+2), so we elected to stick with the OEM units and changed spring rates instead at +3. That was a gamble that some thought was strange, since we could have done double adjustables shocks (which we sell) for +2 points instead of springs (we don't sell the VBP spring).

http://vorshlag.smugmug.com/Racing-E...DSC_5821-S.jpg http://vorshlag.smugmug.com/Racing-E...DSC_5807-S.jpg
This was how the car looked while cornering on the B6 Bilsteins + 245 R7s + stock bars and springs.

After driving the car on the 245mm Hoosier R7s at MSR-Houston (above), with the B6 Bilsteins and stock springs, then looking at these pictures... I felt the car had too much roll and dive. Sure, we could have gotten some of that dialed out with adjustable shocks ($3350 MCS monotube TT2 doubles), but probably not as much as I'd like. Tripling the front and doubling the rear spring rates made a bigger change, in my view (and I drove it this second way at MSR-Cresson), so we took a gamble and went that route. I will just have to deal with the less-than-ideal damping offered by the stock replacement Bilsteins. Ideally, of course, we'd change BOTH the spring rates and shocks. That is if we had the points budget, which in this case we just don't. ALL the rest of our points are for the tires - because TIRES ALWAYS MAKE THE BIGGEST IMPROVEMENT IN LAP TIMES.

http://vorshlag.smugmug.com/Racing-E...8_120911-S.jpg http://vorshlag.smugmug.com/Projects...B61G3572-S.jpg
Tires matter SO MUCH and virtually everything we do to the suspension is just to keep the tires happy

So, let's look at the OEM shocks. As I stated before, this 1992 model Corvette base model coupe came with Delco-Bilstein 46mm piston monotube dampers at all four corners, and amazingly the 24 year old original shocks were still on this car when we got it. Unfortunately, two of them were blown, which is to be expected after nearly two and a half decades of use and abuse. So we purchased replacement Bilsteins as close as can be purchased today, and put them on for a "zero point" replacement.

Wrong. Not the original dampers, not legal. This is what the ruling was on item 5.

continued below

Fair! 05-26-2015 12:22 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

http://vorshlag.smugmug.com/Projects...B61G3595-S.jpg http://vorshlag.smugmug.com/Projects...B61G3593-S.jpg

Could we have rebuilt the OEM Delco-Bilsteins instead? Sure, but there were two problems with this idea. First, the time frame we had to build this car back in January (2 weeks) wasn't going to give us enough time to have the old shocks rebuilt. While we are a Bilstein Motorsports dealer, we still don't have the $5000 fill rig necessary to refill the Nitrogen charge in this particular style Bilstein (and that's all it works on). Secondly, if we had said we had these shocks rebuilt, who would have believed we had kept the OEM valving?? We make and sell shocks for a living! That would have been the first thing people assumed - shock guys, cheater rebuild.

http://vorshlag.smugmug.com/Projects...DSC_7878-S.jpg http://vorshlag.smugmug.com/Projects...DSC_7880-S.jpg
These have been sitting in a box in my office since January, in case we were forced to rebuild and use them.

The proof about what came in the 1992 model base coupes is shown below, which are some pages from GM documents which I haven't shown before (Jason researched and found this cache of GM documents for the 1992 model Y-body). There are hundreds of pages of period documents on this version of the C4, so have fun digging.

http://vorshlag.smugmug.com/Projects...standard-M.jpg http://vorshlag.smugmug.com/Projects...ilsteins-M.jpg

We knew these Delco-Bilstein monotubes were the stock dampers but apparently some folks didn't even believe that. So I'm showing this now, since I was warned that I'd lose a protest even if we put these old blown out shocks back on without showing documented proof of the OEM fitments. Guilty until proven innocent, but I guess with a build shown this publicly I should expect this level of scrutiny.

After looking for the exact OEM replacement shocks back in January we found that we could no longer buy these Delco-Bilsteins anywhere, for any amount of money. Not from GM, not from Bilstein, and there were no "New Old Stock" dampers available anywhere (if you find any, please send the link my way!). So, from my SCCA background on similar "stock replacement equivilent" issues we "assumed" that a close alternative replacement to the OEM dampers would be allowed. So we looked and found a set of shocks that were the closest and still available new: Bilstein B6 monotube dampers that are listed in the Bilstein catalog for the 1992 base trim level Corvette. These are a whopping $85 per corner, retail, and we paid less that that with our direct dealer account.

http://vorshlag.smugmug.com/Projects...stein-c4-S.jpg http://vorshlag.smugmug.com/Projects...kauto-c4-S.jpg

And while I didn't go into this excruciating level of detail before, I hid none of this. We showed these B6 dampers in one of my first posts here, but I didn't show that there are about a dozen choices for the C4 from Bilstein... they make some for the base model, others for the Z51, some for different years, there's a B6 and a B8, and of course fronts and rears. This array of cheap Bilstein monotubes is what we chose from to get the two part numbers shown for the 1992 base model coupe, shown above left.

These are painfully similar to the OEM Delco-Bilsteins - they have the same 46mm pistons, same 50mm body diameter, the same shaft sizes, same body dimensions, and no external valving adjustment. You can see the details in the images below, which were captured from the "GM Heritage Center" database of records for 1992 model Corvettes at this link.


I have cleaned up these scans from 24 year old literature published for this 1992 model Corvette, and even highlighted the mention of Delco-Bilstein (its referenced on 6 different pages) and even the dimensions of the shocks. And the swaybars - which are still the OEM units. These Delco-Bilsteins are functionally identical to what we have been using (the $85 B6 dampers), but that's not good enough to be legal as +0 point shocks, they have to be the actual 24 year old Delco-Bilsteins, which we'd need a TIME MACHINE to get a hold of a new set in 2015.

GM doesn't keep original stock parts on hand for more than 10 years, but they instead have a "generic replacement part number" that supersedes the original 1992 shock part numbers. This replacement part number is shown for all 1989-1996 Corvettes without the adjustable (FX3) dampers. Its a $28 piece of crap twin tube shock that is so dissimilar to the 1992 model OEM damper that its almost funny. Not gonna happen on my car, no way.


Anyway, long story short - we are now sending the old and blown OEM dampers (shown above) directly to Bilstein, having them rebuild them, and then asking them to include documentation that they didn't alter the valving in any way. I'll have them seal the shocks in tamper-proof tape if they can, too. And someone will probably still accuse us of cheating, oh well. These "cheater" B6 Bilsteins will be for sale here soon after - cheap!


I wish I could take people for a ride in this car on track with these B6 Bilsteins. Well, with no right seat that ain't gonna happen. Any way, the C4 on these shocks rides like a big underdamped mess at speed. This is not a great set of dampers, not by a long shot. But they are just the closest thing we can find to OEM that isn't leaking. At $85 per corner, you get what you pay for. But that's not good enough - I have to use actual OEM shocks, not OEM replacements, or take +2 points (and move to TTB). And the burden of proof is on the DRIVER.

Whatever the answers to life's big questions, we're going to make SURE this car is squeaky clean at Nationals. If I get protested over some bullsh*t non-performance hidden rule detail, I'm going to share it here for all the world to see. Hopefully, after this 5 part protest and the resulting changes we will make to 4 items, it will be smooth sailing from here on out.

What's Next?

We're desperately trying to get the motor back and installed in time to make Hallett June 13-14, but time is not on our side. I'd also like to get the following changes, modifications and completed before NASA Nationals East:
  • Since my red Suzuka trade fell through after the fact (not my fault), we have to install a new driver’s seat (black Cobra Suzuka GT width Kevlar seat just arrived)
  • Add a massive oil catch can + breather system to the motor
  • Add aftermarket oil pressure, oil temp and water temp gauges
  • Install poly bushings throughout + machine offset Delrin bushings where needed
  • Design and build front brake cooling + new braided brake lines
  • Build support frame for rear plexiglass hatch and install
  • Move full sized battery to rear cubby hole + rewire main battery cable with main power kill
  • Make aluminum covers for ABS and battery cubby holes
  • Take car for interior paint + cage paint, exterior repairs + left side and front end paint
  • Complete the new livery package with stripes #RAMPAGE
  • Spend last point on proper custom cold air and hood venting

Lots planned before Nationals, and some of it might be protest bait, so we might hold off if it seems unnecessary. Again, the way that the internet protest went down was a bit weird, but look at this build thread - the pictures, the details I'm sharing, the SMACK talk in my first post? I probably should expect this level of scrutiny more often.

That's all for now - will update once the motor is back! Thanks for reading,

Fair! 08-21-2015 05:22 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for August 21st, 2015: Its been almost 3 months without an update, and while we have knocked out a few things on the C4, mostly we have just been waiting for the rebuilt motor to arrive. We're less than 2 weeks from NASA Nationals East and I had hoped by now to have the motor in, a few race weekends of tuning under our belts, and ready to go to VIR "fangs out". But a big delay on the motor has crushed our hopes and dreams a bit, heh. Read below to find out where we are on this project.


But first, in celebration of Grassroots Motorsports magazine's annual "Wear Your Helmet To Work Day" (Aug 21, 2015), I give you our submission we took this morning at Vorshlag. This shows almost everyone here "working" on the 69 Camaro Pro Touring / Track Car we're building for a customer (latest update here). That was fun and GRM shared our picture at the top of their page of submissions on Facebook. Installing an intake manifold on the roof like a pro? I think we nailed it.

The Best Laid Plans...

So back in early May I had hoped for a quick 2-4 week turn around on the very basic rebuild on the 24 year old LT1 motor. Paid up front to help speed things along at the machine shop, too. I really wanted to make the June NASA event at Hallett, because if I could have made that event (and scored points both days) we could have salvaged a chance at winning TTC in the Texas region season points battle. We only get 4 "drops" for the year in region, and with the issues we had at MSR-Cresson in March I didn't get any points either day, so that's 2 drops. Then we missed the "last ever" NASA event at TWS in April (we ran the TT3 Mustang for one last time), so that's 2 more TTC drops. Making Hallett would keep us in the points...


Nope, that deadline came and went. Its been 14 weeks since the motor shipped out to the machine shop, but I keep hearing "pretty soon". Pretty disappointed, and if the motor doesn't arrive in the next handful of days we miss NASA Nationals East (13 days from today). We are moving forward with every hope that the motor shows up, then we can thrash to get the drivetrain reinstalled, get the dyno tune re-checked, install the new Peterson oil catch can (below), then rush out to ECR or another local track for some shake down testing. If it looks good there, then we'll pack up and tow 17 hours to VIR for NASA Nationals East September 4-6, 2015.


But seeing that we would have to leave in less than 13 days, and I have no motor, I kind of doubt we will make it. Some valuable lessons learned, mostly "take your motor out the day after it breaks" and "use a local engine builder" who is close enough to knock on their door. Daily. Oh well, fingers still crossed. Let's go ahead and cover the work we've done in the past 3 months to this car. Even if the motor returns after Nationals is over, we will still try to make the 2 remaining NASA Texas events for 2015, just to see how it does in TTC before the chassis is re-classed in 2016 (likely to TTB or even TT1/2/3).


Did want to give a shout out and congrats to Dave Schotz. He took his TTC C4 (built at the same time as our's) to the 2015 NASA Nationals West a few weeks ago and won both PTC ant TTC in his Corvette. He also took the wins in PTC and TTB in his 4th gen Firebird. That's 4 championships in one weekend! Way to go Dave.


The fact that he won TTC/PTC in a C4 pretty much guarantees that the car will be re-classed next year. So that's not good news for us if we miss NASA East this year. We had one shot...

Old Shocks Rebuilt and Reinstalled

If you couldn't tell from my last post where I discussed the "the 5 Point Mystery Internet Protest", I didn't agree with many of the items that were ruled against this car - ruled upon sight unseen, after being protested by a competitor with their name withheld. Oh well, now we all know what to expect when you race in the same class as the _____. (you can fill in the blank)

https://vorshlag.smugmug.com/Project...B61G0863-S.jpg https://vorshlag.smugmug.com/Project...IMG_1215-S.jpg

We got to spend $450 getting the 24 year old factory Delco-Bilsteins rebuilt by Bilstein-USA. Since we paid for a rush it only took 5 weeks to get them back, hoping that the motor would arrive in that time. Money well spent - these sat around for only 2 more months before we even installed them.

https://vorshlag.smugmug.com/Project...B61G9996-M.jpg https://vorshlag.smugmug.com/Project...zeRender-S.jpg
Biggest difference in the OEM vs OEM replacement Bilstein dampers sets? Blue vs Black dust boots. #CheaterShocks

We made sure to get documentation from Bilstein, showing that they only replaced the seals and wear items. The original shocks' shims and pistons were left alone. But who cares? Nobody believes anything they read on the internet anymore. These pictures are probably only good for use against me in a future internet protest, hehe. ;)

https://vorshlag.smugmug.com/Project...B61G0006-S.jpg https://vorshlag.smugmug.com/Project...B61G0001-S.jpg

Olof swapped out the "new" $85 Bilsteins replacements for the $450 rebuilt 24 year old Bilsteins in 1.27 hours of non-billable time. They look identical to each other, but we didn't bother to dyno both sets to prove how equally pitiful the two sets felt. I'm sure they are just as floaty as the "new" set was.


8.5 BTM (Base Trim Model) Definition, Updating and Backdating Rules
For the purposes of NASA TT Modification Points assessments, the term BTM will be defined as follows: Any part that is identical in size, shape, and functional characteristics compared to the part that originally came on the vehicle, from the manufacturer, as a standard feature of the base trim model as it is listed in section 8.2 Base Classifications (factory options and specialty model parts are considered non-BTM) or is listed as a standard replacement part by the manufacturer (OEM).

Some parts that are produced by aftermarket manufacturers as generic replacement parts may not require a points assessment provided that: they are the same size and shape, and have the same functional characteristics as the BTM part, and that they provide no significant improvement in performance, longevity, or reliability. If it is determined in impound that such a part does not meet the above description, the driver may be disqualified. Consultation with the Regional TT Director prior to competition is advised for any driver using a vehicle with replacement parts that fall under this exception.
This is sufficiently vague as to mean "we can pick when we want a replacement part to be legal". We learned from this ruling and the precedent set that: unless you are using the original, as-delivered factory base trim level shocks on your TT letter car, you should just take 2 points for whatever shocks you have installed. There is no "OEM equivalent" for these mysterious and mythical parts called "dampers". You were warned. :)

Remove Cage Tubes

Speaking of wasted hours, Olof spent another 2.4 hours taking these roll cage bars out. Yay.....

https://vorshlag.smugmug.com/Project...DSC_8596-S.jpg https://vorshlag.smugmug.com/Project...DSC_8599-S.jpg

Again, I completely disagree that these two optional bars forward to the firewall aren't 100% legal (again, without taking points we didn't have). They were installed as no-points tubes to the letter of the rules, but the "unwritten" wording is what got us. They weren't below the top of the tire, which is true - even if that phrase is nowhere in the NASA rule book.

https://vorshlag.smugmug.com/Project...DSC_8605-S.jpg https://vorshlag.smugmug.com/Project...DSC_8606-S.jpg

These two optional bars connecting the door bars to the frame on the passenger side weren't legal without taking points. I still think its silly to encourage asymmetrically safe cages, but we pulled those two bars out.

https://vorshlag.smugmug.com/Project...DSC_8614-S.jpg https://vorshlag.smugmug.com/Project...DSC_8615-S.jpg

Once the 4 tubes were cut out the flapper wheel on the electric grinder was used to get the stubs of tubes smoothed flat. It took time and made a huge mess, but there's now no sharp edges to catch a driving suit or cut your skin, if snagged. And more importantly, there's no nit-picky visible items to protest. #CheaterCage

https://vorshlag.smugmug.com/Project...DSC_8634-S.jpg https://vorshlag.smugmug.com/Project...DSC_8635-S.jpg

Cutting and grinding the cage to get these tubes out made a lot of metal dust, which went everywhere inside the car, so Olof spent another 1.15 hours cleaning out the entire interior. With some oil that was spilled in the floor on the passenger side (when "Old Smokey" was giving its last death throws at the NASA MSR-C event), and piles of metal dust, it made a real mess. But he got it cleaned out and ready for the replacement Cobra Suzuka GT seat - which is here and going in later today.

continued below

Fair! 08-21-2015 05:30 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

Engine Bay Power Wash + Seat Swap + Firewall Re-seal

https://vorshlag.smugmug.com/Project...DSC_8569-S.jpg https://vorshlag.smugmug.com/Project...DSC_8571-S.jpg

Having the drivetrain out sure makes for a perfect time to clean two+ decades of crud out of an engine bay. This one had it all - oil, dirt, funk, and grease. Brad rolled the car out back and fired up the pressure washer in 105°F heat and got it blasted clean under there.

https://vorshlag.smugmug.com/Project...DSC_8574-S.jpg https://vorshlag.smugmug.com/Project...DSC_8597-S.jpg

Once inside I used my "WD40 all the things" trick to shine up the old painted surfaces and rubber. Let that soak then wiped it down.


After the cage tube removal mess we cleaned the glass inside and out with Windex and newsprint, to polish the glass. First time I've been able to see out of the glass in all directions without looking through some film of decades-old funk.

https://vorshlag.smugmug.com/Project...DSC_8653-S.jpg https://vorshlag.smugmug.com/Project...DSC_8654-S.jpg

Today Olof installed the new Cobra seat (the red one went away) and then re-sealed the firewall. There is an aluminum panel where the old factory blower motor/heater core box was in the engine bay, and it leaked a bit of oil into the passenger foot well when the motor smokified. That's finally water tight and should be leak free.

Now we just need a motor...

Aluminum Griffin Radiator Upgrade

One of the things I had hoped to do at VIR was take a lot of laps. I have never driven that track and it has a LOT of turns, so I was hoping to make every session from Friday-Sunday, to learn the line and hopefully put in a good time. I was going to take 2 or 3 sets of tires on 2 sets of wheels, too.


Originally Posted by 2015 NASA TT rules
8.3.I.c.3) Radiator upgrade/shrouding/fascia modification (drilled or cut holes/slots) that only provides increased airflow to the radiator or oil/transmission coolers (without aerodynamic or engine air intake improvement), and/or radiator core support modification/replacement

To ensure that the car ran smoothly for longer stints on track at VIR, I wanted to upgrade the radiator. This is FREE in TT-letter class, by the way, for all of you rules Nazis looking at this build (see the "No Points Mod" rule above, which is from page 35 of the 2015 NASA TT rules).

The stock radiator is already pretty sketchy design, with a tiny aluminum core and glued plastic end tanks. They fail over time at the tank to core junction. This looks like the original piece, too. So I looked at direct fit C4 radiators that were all aluminum and beefed up in size. $545 for one, $625 for another, and all of them would take 6-8 weeks to be built. Nope!

https://vorshlag.smugmug.com/Project...DSC_7803-S.jpg https://vorshlag.smugmug.com/Project...DSC_8611-S.jpg

The OEM radiator is bundled with the A/C condenser (already removed) in this fiberglass, factory duct box. It has no filler neck, as the car has a remote coolant reservoir tank higher in the engine bay. The two fans and shroud look sufficient, and don't do anything at speed anyway. I measured the radiator core size and did some searches...

https://vorshlag.smugmug.com/Project...B61G0765-S.jpg https://vorshlag.smugmug.com/Project...DSC_8613-S.jpg
We used the generic Griffin aluminum radiator for a mockup in the 69 Camaro (left), which fit that frame spacing well

Summit Racing catalog has 2,312 different aluminum radiator listings just from Griffin. So I picked a NASCAR style Griffin radiator of the same basic height and width, with the same inlet/outlet layout, but with a massive 3" thick dual core. This was a $175 retail part, now we just had to modify it to fit this car...

https://vorshlag.smugmug.com/Project...DSC_8626-S.jpg https://vorshlag.smugmug.com/Project...DSC_8623-S.jpg

Olof then modified the "generic" radiator to fit inside the C4 shroud and frame layout. The lower radiator hose was angled, so that was cut off and the hole plugged. It needed to move upwards a few inches to clear the front cross beam (see below), so he drilled a new hole and moved it there. Then he modified the fiberglass radiator shroud/housing/mount to clear the inlet on the top left corner. The radiator neck was cut off and capped, then a matching "steam line" was added. This was done with a weld bung and re-using the fitting that came with the Griffin, which was threaded into the water neck for the overflow port.

https://vorshlag.smugmug.com/Project...DSC_8631-S.jpg https://vorshlag.smugmug.com/Project...DSC_8632-S.jpg

It worked out great and took a total of 4.05 hours in total for Olof to: remove the OEM radiator assembly, modify the radiator (cutting and TIG welding), pressure test the modified Griffin unit, modify the brackets/mounts inside the fiberglass shroud, and reinstall everything. In the end we got a LARGER capacity Griffin radiator that fits better and is bigger than anything we could have bought that was a direct "bolt in" for the old C4.

https://vorshlag.smugmug.com/Project...DSC_8630-S.jpg https://vorshlag.smugmug.com/Project...DSC_8637-S.jpg

During that 4 hours of work Olof also made an aluminum cover for the gaping hole in the side of the fiberglass box where the A/C bits passed through (visible above left). The new radiator was bigger in every dimension just enough so that it barely fit in the fiberglass enclosure, and there wasn't even room for rivets to hold this panel on - so it was bonded with epoxy and held in place while it dried with the green tape. There were also weather-strip seals added next to the new radiator to better seal it to the inlet/outlet sections of the fiberglass duct - that should be better than the factory airflow management in the radiator box.

We're really ready for the motor....

What's Next?

I just heard back from my engine builder minutes ago, and he says the last "hard to find OEM LT1 engine parts" are finally there. He's supposed to be wrapping up the motor this weekend, then bring it personally to our shop since its so late (no time for pallet shipment). So I'm hoping he's right, and we might, just might, get this car together in time to make VIR in 2 weeks. They need my entry for TTC to "make a class" at Nationals, so others are counting on us to be there, too.

We had a lot of other plans we would have implemented if this car was put together 2-3 months ago, like we had hoped for. Things that are small incremental improvements in weight balance, airflow, safety, etc. But with virtually no time left to test even if the motor showed up tomorrow we're holding off on more changes to the car. Too many changes means too many risks of something done that fails - and I cannot afford for any failure if we make it to VIR in 2 weeks. I need an uneventful weekend with lots of track time, some good lap times, and no trivial protests.

Now we just need a motor...

More soon,

Fair! 10-17-2015 02:55 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for October 16, 2015: Its been another 6+ weeks since my last post, and it has been a roller coaster ride of ups and downs. The rebuilt motor finally showed up on October 6th and was a week long thrash to try to get the car together for a track test October 10th at ECR and a NASA race weekend Oct 16-18 at TWS. We had already missed the September NASA event at MSR-H so we are really pushing to get the car to the last 2015 NASA event in Texas. Unfortunately things did not go to plan and we're scrubbing this race. Let's cover what has been done since my last update to explain...

Note: After writing this update over the course of 2 weeks of work on the car, I had my thread update completed in a private section of our forum - which we use to compose and edit these mega sized build thread posts. Jason had edited everything the night before I scrubbed the event, and the morning I was going to post this (Wednesday the 14th) our forum crashed and has been down ever since. Its so borked that the server is auto-generating 20,000 error message emails a day, driving me nuts, and I have two teams of tech gurus working on fixing it (we've had that forum operational for 13+ years and its never gone down like this). Luckily I had this post open on a window on my pc, so I could copy the text, but it lost all of the UBB code for formatting, images and links. In a rush to rewrite this post now I won't link all my pics to larger images like I normally do and might miss some links I had in here before.


You will notice in this series of posts that I'm not sharing any pictures of the inside of the rebuilt motor and censoring some images where those bits are visible. I'm not going to stop sharing pictures in this build thread, as it is still part of showing "what can be done on a budget" and "what race prep we can do" at our shop, but I'm not giving any more ammunition to our competition!

Rebuilt Motor Arrives

Let's talk about TT-letter class allowable engine rebuild rules. Here they are:

Originally Posted by NASA TT Rule 8.3.i.c
18. Engine rebuild with head shave, block decking and 0.020” overbore provided that compression ratio is not increased by more than 0.5 and displacement is not increased by greater than 1.49%. Forged pistons and internals are legal; however, they must be of equal or heavier weight than the BTM parts, and points must be assessed for de-stroking, and/or increased displacement and compression ratio if greater than the limits listed above. (Note: 0.020” overbore with OEM rods and overbore pistons will yield an increase in displacement of approximately 1.1% for most engines.) If forged internals used are lighter than the BTM internals, then Dyno Re-classing (Section 8.4) should be used to prevent disqualification.

19. Engine balancing and blueprinting

20. Removal of the engine balance shaft and/or balance shaft drive mechanism

21. Non-BTM valve springs and retainers, piston rings, and rotary apex seals

My engine builder worked with me at length throughout this build, and sent plenty of images during the rebuild process, but I'm not showing any those here. NOPE.

This engine is a NASA letter class legal rebuild, with nothing out of the ordinary. I'm not going to get into the specifics of what we had done to this LT1 engine, but I will say that it was a 100% legal rebuild. No grey areas, no loopholes, just a solid TT-letter class legal engine rebuild that will likely pick up zero horsepower, only reliability. This engine would survive the most brutal tear-down protest. It is also very well built, uses all new parts, and was not cheap. The engine builder even made fun of the fact that we were having to use OEM rockers, pushrods, rocker studs, guide plates, etc. "I've never had anyone ask to use the stock stuff before!" We went over the rules with him in detail, and he is a racer himself and understands how important rules legality can be.


The engine took over 5 months to be rebuilt partly because so many of the 1992 model specific OEM parts were tough to procure (this "GenII" V8 engine family was only used from 1992-96 and the Corvettes used different parts than the Camaros or Impalas of this generation), and there were parts changes for almost every year of this LT1 - we can use any 1992-96 LT1 Corvette engine, but only as a complete assembly - no mixing and matching of parts like camshafts, heads, etc. We stuck with all 1992 stuff, but it wasn't necessarily the best choice.

There were nationwide searches to find some of the items needed, which took a lot of time. I'm not going to bore you with the trials and tribulations of building a 25 year old motor with many of the OEM parts, but it was a bit of a nightmare. And the engine builder admittedly had some inexcusable delays on his part, but it finally got here as an assembled longblock at the 11th hour, just in time to make the last NASA Texas race of 2015. Yes, this was long after 3 more NASA Texas events passed + NASA Nationals East was missed, which I was none too pleased about. We missed almost the entire NASA race schedule, but we hoped to make the last event here...

Parts Cleaned, TB Airfoil Removed, New Plug Wires + Wrapped Manifolds

The longblock was placed on the engine stand mid-day Tuesday October 6th and then the washed and cleaned Moroso oil pan was installed with a new FelPro gasket and some RTV. Then it was onto several other checks, then the intake manifold and valve covers were cleaned up on Wednesday...

These would be installed after the motor was back in the car, to save time. Some deadlines were looming: be at True Street for dyno checks and possible re-tune that Friday, then out to ECR on Saturday for track testing, then any last minute updates the following Monday-Thursday, then load up and head to TWS for a NASA weekend the next Friday-Sunday. Plus our shop was full of customer cars that all had their own deadlines, many going to the same TWS race weekend.

https://vorshlag.smugmug.com/Project...IMG_1039-S.jpg https://vorshlag.smugmug.com/Project...IMG_1038-S.jpg

While the guys were putting the LT1/ZF6 drivetrain in the car Wednesday morning, I took the intake and valve covers to Friction Circle Fabrication in Lewisville to have these 25 year old parts cleaned in their UltraSonic parts cleaner. These dirty bits were soaked in the 155°F degreaser solution and agitated for 90 minutes, but they came out super clean. In hindsight we should have scraped more of the burned oil residue off the valve covers mechanically before going in the ultrasonic - would have saved a lot of time.


It is a good feeling to know your new engine isn't going to be filled with trash that fell off of some dirty part you reinstalled. And there was some serious crusty, nasty stuff on the bottom of the valve covers and inside the intake. Old, burned-on oil residue plus liquid oil in the intake - from the massive blow-by - which was being pumped back into the intake via the PCV system.


When I returned with the cleaned parts, Ryan installed the intake manifold (which was a chore - long story) plus the 25 year old OEM injectors. The stock injectors were cleaned and flow bench tested at InjectorRX in Houston back in August, and as you can see with the test results above, the flow rates were all over the map. Three of the units were also leaking and all of them were clogged before, but after they were (ultra sonic) cleaned and rebuilt they all flowed the same. Good insurance on a set of OEM injectors this old - and yes, we have to use the stock parts here, or take more class points we don't have.

https://vorshlag.smugmug.com/Project...IMG_1833-S.jpg https://vorshlag.smugmug.com/Project...IMG_1837-S.jpg

The aftermarket throttle body airfoil, which we didn't know was installed until someone noticed and pointed it out from one of my build thread pictures earlier this year, was removed when the intake manifold went back on. The one NASA event where we (unknowingly) ran this airfoil on the car and actually got a class win, we had the points for it (+2 points), as we hadn't done spring upgrade yet (+2). These throttle body "air smoothing" airfoils were super common to run "back in the day" on the TPI and LT1 V8s built from 1985-1996, due to the abrupt shape change of the twin throttle body set-ups GM liked to use back then. Nowadays the LS-series GM V8 engines use a single round throttle blade, which feature smooth inlets and MASSIVE throttle blades (and flow) in comparison.


Anyway, the airfoil is no longer on the car, and is sitting on my desk as a paper weight.

With the valve covers and intake off, you get a big helping of NOPE

Before the motor went going into the car we replaced the AutoZone plug wires with some 8mm Taylor wires made for this LT1 Corvette - these are a bit easier to change with the engine out of the car. The old plug wires were still fairly decent looking, but why chance it when the motor is out? Spark plug wires are "free" per 8.3.I.c.6, for any rules lawyers that are reading, and the costs were around $65. I tend to use Taylor plug wires on everything we build around here. New NGK split electrode spark plugs were also used - we've seen good results from these and they don't have itty-bitty iridium or platinum tips that can fall off.

https://vorshlag.smugmug.com/Project...B61G3580-S.jpg https://vorshlag.smugmug.com/Project...B61G3579-S.jpg

The OEM exhaust manifolds were also wrapped with DEI header wrap before going on, to keep a little heat out of the engine bay. As we've done throughout this build, if it has to come off or for some other reason we have to touch a part, we're going to make it better - to the limit of the rules and within sane budgetary constraints. Header wrapping the manifolds is legal per NASA TT rule 8.3.I.c.23. Ryan used an old hot rodder trick to wrap these manifolds - he pre-soaked the DEI wrap in water, to make the material more pliable during installation. It was wrapped tightly around each tube tightly then secured with safety wire at the ends. The water boils off quickly during start-up, if the wrap hasn't completely air dried by then.

Drivetrain Installed + Oil Catch Can/Breather Install

The re-installation of the engine is pretty boring work, but it does eat up time. And like everything else, doing this work on a Corvette is more cumbersome than most cars. The ZF6 speed was pressure washed and cleaned up (previously covered in oil from the old RMS leak) before it was bolted to the motor. Everything we touch on a race car goes on clean, even old OEM parts. Dirty parts help hide leaks, cracks and other issues.


Assembling the triple disc clutch to the flywheel, stabbing the transmission and hydraulic TOB, and getting everything into the car was handled by Ryan and Brad. It takes more time to line up the clutch plates and get all 6 pieces lined up together, but this is not hard for our crew. A metal clutch alignment tool is a must for these multi-disc clutches, by the way - we use an old T56 input shaft.


After the drivetrain is in place, the big aluminum C-channel that connects the diff to the transmission goes in (which also functions as the transmission mount, just like on a Miata), as well as the stock aluminum driveshaft. Then the OEM exhaust system goes in, the stock shifter is installed, various wiring harness plugs are attached, etc. No pics of that as Brad was helping and I was across town. This car still has the original OEM mufflers and catalysts, which we visually inspected very closely before the motor went in - the catalyst matrix is still intact after all these years, somehow. Changing the manifolds, cats, mufflers or even the tail pipes costs points in TT-letter classes, so it all has to stay bone stock.

https://vorshlag.smugmug.com/Project...B61G9453-S.jpg https://vorshlag.smugmug.com/Project...B61G9825-S.jpg

After the engine was in place, we did one more (zero points) upgrade I had planned on for a while, and one we do in a lot of customer's race cars (see above) - add an oil catch-can/crankcase breather. This is something smart to add to any car that sees track time or extended RPM use. The way we plumb these, and how we specify the catch can itself, depends on if its an emissions legal street car (above right) or a track-only race car (above left). A street car isn't supposed to have an open vent for crankcase fuel/oil vapors to get out to the atmosphere, so street driven cars are plumbed with a PCV system to pull excess crankcase vapors out during deceleration and route them back into the intake manifold, to burn them in the engine. Liquid oil in the crankcase vapors is trapped within media inside the catch can, which can collect in the can and be drained out after track days. On a race car you don't have to do with a PCV system - and you don't want to.

This is how much smoke was coming out before the engine rebuild... that's all blow-by

One of the main problems we had with the LT1 motor in the Corvette earlier this year was tons of blow-by. Combustion by-products getting past the piston rings and valve guides/seals then pushed into the crankcase. This was only realized after the leaking oil pan gasket and rear main seal were fixed before our second 2015 NASA event in this car. The blow-by was from worn out rings, three valve guides that had lots of play, and valve seals that had crumbled over two and a half decades. It was smoking so badly we couldn't make one lap without being black flagged.

This is the Peterson 08-400 catch can / breather tank we used

Since I didn't want to take any chances after having "that smoking Corvette" for two NASA race weekends this year, I ponied up for a Peterson Oil Catch Can / Breather a few weeks earlier. It has two -12 AN fittings for inlet, a -6 for a drain (which comes plugged), and the built in breather in the cap. Even comes with a nice mounting clamp. So when the motor was back in the engine bay Ryan and Brad mounted the breather can on the firewall, then plumbed some -10AN bulkhead fittings to both valve covers (because that's what fit the OEM hole on the passenger valve cover).


One fitting went in the factory PCV suction line on the passenger valve cover but the driver's side cover had to be drilled. We have removed the PCV valve and function completely. These factory LT1 "center bolt "valve covers are magnesium and tricky to work with, but they were drilled handled properly and plumbed with -12 sized push-lock 300 psi hose and -12 AN fittings into the Peterson tank.


Now both valve covers vent will excess crankcase pressure to this oil catch can, without the need for a vacuum source to "pull" the vapors out. This Peterson catch can has an integral breather in the lid, which is what makes it not street legal. We have completely done away with the PCV system, so now it is less troublesome and won't allow oil and/or unburnt fuel vapors to be returned to the intake track to be burned - which can cause detonation. And if you get a lot of blow-by it won't send liquid oil back into the intake, which is really bad.

First Fire + Weird Ignition System Issues?

After the breather tank was plumbed, all of the engine fluids were topped off and some Royal Purple break in additive (zinc) was added to the 10W40 Mobil1 synthetic oil we used for initial break in (normally I like to run 15W50 in race cars). The ignition coil and the fuel pump relay were disconnected, then the engine cranked for 10 seconds, and it made 20+ psi of oil pressure almost immediately. After that the coil and fuel pump were hooked back up, the fuel pump was triggered a few times (key on/off... on/off.... on/off) to prime the fuel pressure in the lines and fuel rails, and then it was cranked. And cranked. And nothing. No start.


Then began a full day chasing the starting problems. First we assumed the obvious: it was Optispark related. This is the name for the system GM tried (and failed) at making a better distributor with in the GenII V8s, with a weird unit is driven off the timing gear at the front of the motor. This is widely known as a problematic system. The GenIIs camshaft drives the water pump, also strange, which feeds the motor with coolant in the reverse order of any other motor on the planet. The water pump is right in front of the Optispark, and if any coolant/water gets in the Opti, it usually dies. The LT1's two main bad ideas were the Optispark and reverse flow cooling - they were both abandoned in the next generation engines by GM (GenIII LS1).

https://vorshlag.smugmug.com/Project...IMG_1087-S.jpg https://vorshlag.smugmug.com/Project...IMG_1097-S.jpg
Checking fuel pressure, computer issues, wiring harness breaks at Vorshlag (left) and True Street (right)

The other issue we kept running into was thought to be VATS related, or Vehicle Anti Theft System. There's a chip in the ignition key that tells the computer "Hey, I'm legit!". Without that handshake the fuel pump won't fire. It intermittently worked, so we have to disconnect the battery to clear it up. Something I thought was removed when True Street tuned the car, but the SECURITY light kept flashing. The VATS on my 1999 GMC truck was doing the same random faults a few months ago and Sean from True Street plugged in and turned that mess off, too. GM "VATS" is pretty much a "leave me stranded in my own car" system.

continued below

Fair! 10-17-2015 02:57 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

The Optispark previously used in this C4 was an aftermarket $500 MSD unit that had less than 3 hours of use on it, so I doubted it could be bad. Maybe a ground wire was missed, or a wire cracked during the install (from age) on the factory harness? Ryan and Brad broke out the factory 1992 Corvette manuals and went through the Ignition Troubleshooting Flow Chart, step by step. Everything they checked worked, we just didn't have spark. Voltages were checked in the harness and into the Opti at several locations. The coil was swapped out for an MSD LT1 unit we had in the shop. No help.

Finally we broke down and ordered a stock replacement $150 Optispark unit from O'Reilys, which showed up 10 minutes later. It was 3 pm the day before our scheduled dyno day and track test, so it was worth the peace of mind.

This small victory was short lived - the problem never really was in the Optispark

We plugged the new unit into the engine harness, put the coil lead near the cylinder head, and spun the drive on the Opti... pop-pop-pop. We had spark, so it was proven to work. So out came the nearly brand new MSD Optispark unit, which meant the water pump we had just installed had to come back off. Order more gaskets while that's being swapped in. While the MSD Opti it was off the car they did the same "off the car" test and... damn it, the MSD unit worked like this, too. So I had to make the call... put the problematic MSD unit back on or have them install the brand new OEM replacement Opti? I told them go with the brand new unit.

By this point we had called and spoken to several LT1 experts and got suggestions from "bad ground", "bad ignition module", "bad ECM" and of course "Its the Opti!" It is almost always the Opti, but I doubted that more and more as we tested the old MSD unit off the car and it came back as good.

Another short lived victory - it started with the new Opti, but ran poorly

After a long day of troubleshooting the engine and with the new Opti installed, the engine fired up and ran briefly with the water pump off, so that was good. Then the water pump and coolant hoses had to go back on, the coolant get filled (with distilled water + Redline water wetter) and burped again, and the front of the engine went back together - drive belt, intake tube, etc.


What should have taken an hour to wrap up that Thursday morning ended up taking all damned day. The engine was finally started, it ran (poorly), the coolant system burped, temps checked out and loaded into the trailer for a dyno test the next morning. It was 7 pm and everyone was glad to go home.


Still, it just wasn't running that smoothly. The engine was idling way too high, way up at 2000 rpms, and it had a throttle tip in stumble. Our LT1-expert Ed stopped by and got the set-screw on the throttle blade set to turn ever so slightly and now it would idle at 1600 rpms, but it wouldn't go lower. Hmm. Also, after the engine warmed up, it wouldn't start again easily. It would crank, but wouldn't fire. Something still wasn't right. After 10-15 minutes of cooling down (it barely got up to operating temps) it would fire up, but once it was warm again and we shut it off, then tried to restart it - nothing. Just cranked, no fire. What is going on here? We scoured the car looking for other issues - grounds, broken wires, etc.

The guys at True Street had been ready for us to come by mid-day Friday for a dyno check and re-tune, but with the Optispark + other issues, we were delayed by several hours and missed their deadline. I called them at 4 pm and told them we were going to miss that window. Luckily they were hosting a big "dyno day" setup the next morning, so I planned to get there early and be first in line.... then head to ECR for a member day track test right after that.

Dyno Check at True Street, Saturday October 10, 2015

Loading the car into the trailer with a triple disc clutch is a PITA, but we hadn't stopped long enough to make front (or rear) tow hooks for this car. So when we got to True Street Motorsports at 8 am Saturday morning, an hour before they opened, Amy and I just rolled the car out of the trailer. Then I tried to start it...


NOPE. It cranked like a champ, but once again the coil wasn't firing. It won't start now, even cold. We fought with it for a solid hour, clearing the battery and trying again and again. It got to where the battery was losing voltage, and it still wasn't starting.


I thought about asking the guys at True Street for a hand, but they were all busy getting their shop cleaned up and ready for 200+ people, who had started arriving in droves. They had a food truck setting up, and cars starting to get dyno'd when we decided to abort the dyno test and load up.

Missing this open track day at ECR was a huge disappointment, and it put me in a foul mood for the rest of the day. I knew we would have to spend more (unbillable) hours the next week to get the C4 running "right" and starting consistently before going to NASA @ TWS the following weekend, without any test time on track. With a new motor, new radiator, and new crankcase breather. Testing this many new things during a competition weekend sounded like a bad idea, and it is.

More Testing At The Shop + True Street

Monday morning we unloaded the Corvette at Vorshlag again and Ryan and Brad spent most of the day tracing circuits and testing everything, wiggling the harness, and looking up issues with these cars. More and more evidence started to point to a bad ECM - the 25 year old engine computer might be at fault. My ops manager Steve started chasing down replacement 92 Corvette ECMs and that search went well into Tuesday. He called dozens of wrecking yards and LT1 re-programmers, parts suppliers and GM dealerships across the country. Nothing, nada, zip - no 1992 Corvette ECMs anywhere.

Just to eliminate any last "part problems" we ordered a new ignition module and replaced it. This was mounted it to the coil/module bracket with proper Heat Sink Compound. Then we spaced the module + coil bracket away from the cylinder head for heat protection from the engine. No change.

Sometime around mid-day Ryan had done some sleuthing online and found a number of 92 Corvette owners with eerily similar problems. One suggestion was to remove the PROM chip inside the ECM housing and re-seat it. Another said to "whack the ECM a few times, hard!" After doing those two things the car started up again, but still ran a bit rough. More tests were done, but it at least ran. We called True Street, who were backed up with tuning work for 3 weeks... I begged, and they agreed to call me back if they had an opening. As luck would have it they had a last minute cancellation and were able to sneak us in for a dyno check-up. I towed the C4 up there Tuesday after lunch and they got to work.

After I left, it wouldn't start again. Sean played with things, checked some codes, and late that day they had found a bad TPS sensor. With the TPS unhooked it would start, but you can't drive the car like this. We had replaced the TPS with a new sensor back in February, after I noticed a weird "throttle dead spot" at the January NASA event. Hmm... red flags were going up.


I spoke with Paul Costas later that night and told him the symptoms we were having, and he related a similar issue he had on his 92 Camaro (which is a GenI TPI V8, but used a similar vintage computer and EFI tech). About a year ago 92 started running poorly and burning up TPS sensors. He talked to an EFI expert familiar with this vintage GM EFI hardware, who said when these ECMs go bad they often lose their reference voltage outputs for 5V circuits like the TPS (Throttle Position Sensor) and IAC (Idle Air Control). He told Paul to test voltage signal at the TPS while driving... and sure enough it spiked way above 5 volts several times, which was what was burning up the sensors.

And we've just burned up another TPS sensor, and the car had a weird throttle response issue when it would run. And the idle was super high (IAC circuit) at some points. I was more convinced than ever that the ECM was dying and emitting some weird reference voltages. But with no replacement ECM for this car to be found nationwide, the chances of making TWS looked slimmer by the hour.


I was stewing over this for days and mid-day Wednesday I decided to scrub the TWS event. We had ECM problems and there was no way to fix it in 24 hours we had left. Crap, crap, crap!

What's Next?

Long term plans had always been to convert the car to a different ECM and harness from a later 1993-96 Base Trim Level Corvette. There were some EFI changes through the 1992-96 LT1 Corvette era which included:
  • 1992 was the first year of the TL1, speed density air metering, and had the weakest computer with the least number programmable inputs
  • 1993 was still speed density but had a more powerful computer with more inputs to alter
  • 1994-95 was another step up in inputs and computing power with the added change of a move to Mass Air Metering, but still OBD-I. Yet these can be reprogrammed via the OBD-I port, no more E-PROMS.
  • 1996 was another big change, such as the move to OBD-II standards, the ECM had a significantly more powerful processor, a LOT more data channels and programmable inputs, and also no longer relied on an E-PROM to change programming.

Checking with all of the parts suppliers we use it appears that new AC Delco ECMs for the 1996 Corvette are readily available, and around $200 (with the core charge). The other years are "iffy" or just downright impossible to come up with reliable units. So it looks like I am going to be chasing down a good 1996 LT1 Corvette engine harness, ECM, Mass Air Sensor, and intake tube next. We could not hope to pull this off in the one day we had remaining before TWS, so that event had to be scrubbed.


We had ordered new R7 Hoosiers, procured a 2nd set of wheels (for the scrub set of tires), event fees were paid, Amy had taken off work, arrangements for the weekend were set, and lots of money thrown at ignition parts that weren't bad - but hey, "that's racing."

Some of you might question scrubbing this 3 day race weekend - since the engine "technically starts" now. Sure, you can unhook the TPS and it might start, but it cannot be driven like this in anger. It is not reliable, and will almost certain break and/or run poorly once we get this thing on track. If we plug in the TPS it will burn that sensor up in short order.

I'm not giving up on this car, and it will likely be run in 2016 up until our "Shop Car" LSx BMW is complete. So look for us at NASA events in January and more likely some TEST EVENTS before then, to verify the new engine and ECM changes we have in store. My next update will be after we make the wiring harness and ECM changes.


Fair! 01-05-2016 03:15 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for January 5th, 2015: Its been a couple of months since I touched base on the progress of Project #DangerZone, our 1992 Corvette race car, and a lot of little things have happened - both to the car and to the NASA base classing rules for 1992-96 Corvettes. We've made some updates to the C4 to hopefully make it lighter (pre-ballast), run cooler, and more importantly - be more reliable once it returns to track use later this month. The C4 is also looking like my only primary race car for 2016, so we're getting a bit more serious with prep on this car and might add a few other racing groups to run the car in. There's only 3 weeks until the next NASA race we want to make in this car (NASA @ MSR-Houston event Jan 23-24) plus a test day at MSR-Cresson the weekend before (Jan 16th at MSR-C). I'm only going to cover the work completed up until now then catch up on the finish work before these two race dates in the next update.


As some of you might know we've started a BMW E46 330Ci build for NASA TTD class. That project has gobbled up some time and we switched chassis before we even began major race prep on the first car (325iC), which slowed us down a bit, but it was the right move going from the 325 to a 330 (the latter of which was classed better and makes a lot more power). You can read up on that car here, which we've named Project #JackDaniels. I explain the name in that thread.

Normally in December of each year, NASA will release an updated rule set for Performance Touring, Super Touring, and Time Trial classes - all 3 of these groups use essentially the same set of rules. PTB-PTF wheel to wheel classes equate to TTB-TTF and ST1/2/3/U equate to TT1/2/3/U. Sometimes the rules aren't published until after the first of the year but this time the 2016 NASA TT rules came out on time, with nearly 8 weeks before our January 2016 event.


The C4 listings above are what we built this car around, and those haven't changed in many years (we know because we have been eyeing this car for TTC for 4+ years). But due to how well Dave Schotz did at NASA Nationals West in his PTC/TTC C4, and how much we riled up a few folks with our forum build thread (even though it really only completed one race weekend), we were expecting either a points penalty (*), class change (TTB?) and/or minimum weight change (increase) to these C4 base classes. So here are the 2016 changes...


All changes from the previous edition of the rules this year are shown in blue. As you can see the minimum weights for 3 of the C4 models were changed, all higher, including our 1992 LT1 base model. We have to add 57 pounds to our weight or else take points for weight loss, which gets expensive. As you may know we had maxed out this build on points from the beginning. Somehow I never really covered that in this thread...

This post on our E46 TTD build thread explained in great detail how we came up with the classing, tire size/compound, chose modifiers and found rules exploits for both the TTD car and this TTC car. I won't repeat what I wrote there in total but if you care to learn some of our secrets, please go here and check it out.

Here is a quick summary of our TTC class build for this 1992 Corvette, based on the old 2015 rules. After we saw the base classing (TTC*) and weights we looked at the Power-to-Weight (P-to-W) ratio assigned to the class (12:1). The * cost us 7 of the 19 class points we had to spend, so we have 12 to play with to stay in TTC. Then we looked at the base tire assigned to the class (255mm). Going up in size costs points, down in sizes nets points back. From there we looked for modifiers to the P-to-W ratio... and found a big bonus (+0.8 ) if we ran a small 245mm or smaller DOT tire (see Appendix B in the rules). 1 point was also gained back because that's 10mm below the TTC class starting tire size of 255mm.

This modifier effectively moved the P-to-W from 12.0:1 to 11.2:1. Luckily the stock LT1 motor could still hit that revised P-to-W limit without any power modifications. This meant we didn't have to burn class points on exhaust or headers or camshaft swaps or intake mods to max out P-to-W. We spent ALL of our remaining points on suspension changes (springs at +3 points) and tire compound (R7, +10 points), plus our point gained back for 245s (-1) and it worked out to the 12 point mod limit for TTC with maxed out power limit.

Let's show those P-to-W calcs "the NASA way" for our TTC Corvette:
  • Weight must be at or above the listed minimum classing weight of 3203 pounds, from the 2015 rules
  • That 3203 number is also just above the minimum "competition weight" modifier numbers, which start at 3200 pounds
  • We chose a 245mm width DOT legal tire (+0.8 P-to-W bonus)
  • The stock engine made 284 whp peak (highest of 3 pulls)
  • 3203 lbs / 284 whp = 11.28:1 (P-to-W) + 0.8 for (245 tire modifier) = 12.08:1

TTC Class "minimum" adjusted P-to-W is 12.0:1, which this car is just a hair over. That's what you want to do - aim for the P-to-W limit and find any modifiers you can to help that ratio along the way. Avoid modifiers that hurt, then use your points to run the best tire compound/width and fix any suspension issues, and add aero if you have any points left. Again, this is more detailed in the E46 TTD thread, linked above.

So that was our TTC strategy for this C4. Now we have to recalculate for the higher 2016 minimum weight bumps, which honestly aren't that bad and are not unexpected. I have to agree with these changes, even if I don't like them. This will mean we have to run even more ballast on the same 245mm tires, which worries me. We haven't dyno'd the fresh LT1 motor but I'm also worried it might make too much power, even at this higher weight (and with the 11.2:1 P-to-W ratio we can now make 291 whp). Even with it only running briefly due to the ECM issues it felt STRONG - and yes, it was a 100% legal engine rebuild. We shall see soon enough.

Sadly our E46 TTD build gained a 7 point penalty with the 2016 rules, which I'm not at all happy about. Really borks the planned build. So of the very few changes made in 2016 both of our TT-Letter builds were impacted. I'm just that lucky, I guess. :)


Meanwhile in last two months, before we got the new 2016 rules, we have been working on some reliability mods to the C4. Of the 2 race weekends we ran this car I never managed to make more than 2 laps in a row. So the stock Z51 brakes haven't been pushed hard enough to overheat, but I'm worried they will be taxed once we get the car on track without a leaking or smoking engine. Why worry? Well because I'm a Left Foot Brake fanatic (learned in my autocross background) and I tend to abuse the crap out of brakes.

https://vorshlag.smugmug.com/Project...ling-022-S.jpg https://vorshlag.smugmug.com/Project...DSC_9462-S.jpg

With an R7 tire compound I don't have to get my best laps in on lap 1 or 2 like we did on the A7s in TT3 last year, so yea... brakes might become an issue. So one day when we had the C4 up in the air for harness removal (see below), I asked Olof to pull apart the front brakes on one corner for a better look. We had built brake backing plates with cooling ducts for a C4 before and he kept the templates we used that time, so this shouldn't be a whole lot of work.

https://vorshlag.smugmug.com/Project...DSC_9450-S.jpg https://vorshlag.smugmug.com/Project...DSC_9452-S.jpg

After he made a flat plate that fit around the hub we discussed where to route the hoses, what sizes to go with, and what shape for the duct at the backing plate. We decided to use 3" oval tube for the inlet, aimed at the hub and inside the rotor face. He built these 2-piece backing plates below.


With only a 13" rotor there wasn't room for a 4" duct, and with the track performance of this car a 3" cooling hose should be enough. Now there's also lower piece to this backing plate added to help seal off the hub section so that the incoming air goes where we want it to. It also allows for a bit of a heat shield from a ball joint that is very near the inside rotor face, shown below.

https://vorshlag.smugmug.com/Project...ling-003-S.jpg https://vorshlag.smugmug.com/Project...ling-007-S.jpg

The spacing from the backing plate to the rotor face (shown in the picture above right) is what we try to stick with, which allows a decent seal to the incoming air but shouldn't ever rub. The goal is to turn the rotor into a centrifugal air pump, with the incoming air forced into the hub area inside the rotor and the curved vanes of the rotor pulling air through the rotor and out radially. This can increase effective braking during a session considerably, as well as extend brake pad and rotor life substantially.

https://vorshlag.smugmug.com/Project...ling-009-S.jpg https://vorshlag.smugmug.com/Project...ling-010-S.jpg

As you can see above left, even the oval shaped 3" duct doesn't put the incoming air completely inside the rotor face, but its as close as we can get without nearly flattening the oval shape. Another thing that we did while the hubs were off was install extended length 3.25" ARP wheel studs. We couldn't find a bullet nosed ARP stud any longer than the itty-bitty stock studs, so we'll just have to start each lug by hand with this fully threaded ARP (it's not like we're doing fast pit stops). The reason why I wanted long wheel studs will make itself known in my next post.

While doing the front stud install we would normally swap in new hubs at the same time, for other cars. But for the C4 we kept the original front hubs - they were still low mileage, still felt tight, and the aftermarket options are total CRAP for this chassis. The only good aftermarket replacement hub for this car worth using is a racing hub made by HPE that costs $699 per corner, and I'm not sure if their solution is even TTC legal, so we'll keep the stockers on there for as long as we can. Brake cooling aimed at the hubs tends to extend their lifespan quite a bit on track, too.


Backing plates are only 1/3rd of the brake cooling solution - you also need INLET ducting at the front of the car and then brake hoses to join them. After looking at the front end of this C4 I wanted Olof to "keep it simple". Why? Well we're likely replacing the bumper cover later in the 2016 season since the stock cover is pretty beat up. We had discussed about re-purposing the turn signals, adding NACA ducts in the old headlight doors, or even NACA ducts under the front bumper... but I wanted to keep it very simple. "Just make a 3 inch round tube and a flange", which is exactly what he did.


Remember - this might not be the permanent inlet duct solution, just a quick one for now. The inlet ducts were relatively easy to make and I had a specific place I wanted them placed. The front of the C4 has a LOT of "front overhang" (see above) where the nose pokes out about a foot in front of the factory front lower air dam (the air dam feeds air to the radiator). All of the radiator cooling is drawn in from under the giant overhang, but there is still some dead space on both sides of the radiator inlet that goes unused...

continued below

Fair! 01-05-2016 03:17 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above


That's where I had Olof place the inlet ducts. "Just drill a 3 inch hole and bolt them in right there", I told him. The inlets are directly underneath the factory headlight holes, taking in high pressure trapped under the nose that isn't being fed to the radiator inlet. There's ample room under the hood (with the flip-up headlight assemblies gone) to route the hoses up and over to the brake backing plates.


Due to concerns Jason and I both had about air pressure bleeding off laterally towards the edge of the nose and bypassing this brake cooling inlet, I had Olof make a little aluminum "brake canard". This is a little air dam that forces some air into a closed pocket to feed the brake inlet. Yes, I know this might incur some aero penalty for TTC. We are going to test with and without these in place and we will add rivnuts in place of the rivets used to attach these little air walls, so we can test with and without them installed.

https://vorshlag.smugmug.com/Project...ling-014-S.jpg https://vorshlag.smugmug.com/Project...ling-013-S.jpg

The brake hose routing looks fairly straightforward, but of course we haven't tested it on track yet. It might rub the wheel at full lock, but since the car is still in the air with the wheels off we haven't checked that yet. A piece of the plastic inner fender liner was trimmed to route the 3" hose below the top of the wheel, but we will see how it fits when the wheels and tires are mounted and its back on the ground.

https://vorshlag.smugmug.com/Project...DSC_5400-S.jpg https://vorshlag.smugmug.com/Project...DSC_9461-S.jpg

Last but not least the car is getting a new set of factory lower air dam plastics. Again, we bought these many months ago just never got around to it. The old bits are beat up and the left sides is held on with Gorilla snot and is half falling off. The new air dam bits will help push more air into the waiting duct for the radiator or the two brake inlet ducts.


Another piece I had purchased way back in January of 2015 that never made its way onto DangerZone was a pre-formed and pre-cut polycarbonate rear hatch from Five Star Bodies. This 1/8" thick, pre-trimmed, formed rear plastic glass was to replace the 46 pound OEM glass rear hatch section.

https://vorshlag.smugmug.com/Project...B61G3356-S.jpg https://vorshlag.smugmug.com/Project...DSC_9454-S.jpg

Removing weight was the primary goal, but with our new 2016 minimum weight numbers going up now this might not make as much sense.


Of course we did this before the new weight numbers came out, heh. Oh well, being able to move weight from up HIGH (stock glass) to down LOW (ballast) is always a good thing. I'm eyeing that 80 pound hood as well.

https://vorshlag.smugmug.com/Project...DSC_9453-S.jpg https://vorshlag.smugmug.com/Project...DSC_9511-S.jpg

Once the glass was removed from the factory hinge at the back of the B-pillar factory roof structure, Olof drilled two matching holes in the trimmed-to-fit and pre-bent Plexiglass. Then he built a frame to give it some support at the lower front corners out of thin wall 1/2" tubing. The two Quik-Latches just arrived and those will take the place of the (broken) rear hatch release. Now we can get into the rear area without crawling through the cage and yanking the emergency release cable in the back.


So if you've read this thread before you know we had some trouble with the original 1992 ECM (Engine Control Module, or computer) after the rebuilt motor went in, that caused us to miss our last NASA race of the year - the car wouldn't start reliably. After days of diagnosis and parts chasing we had finally realized it was a bad ECM. Well we cannot find a new 1992 ECM, anywhere on the planet. 1992 Corvettes had a "one year" ECM - 93 was different, 94-95 was different again, and 96 was also unique. There are no 1993 ECMs left either, but back in October we found plenty of 94-95 Corvette computers available, both new and rebuilt, and our tuner said the later computers were easier to tune for track use. So the quest to convert this to a 1994-95 EFI harness was underway in October.

Instead of trolling junkyards for 20+ year old Corvette engine harnesses, which will bound to have some cracks and wiring breaks, we had a new one built using our 1992 OEM wiring harness for layout. We found several breaks in the existing 1992 harness already - which makes for nightmares when diagnosing EFI issues and the way this one will be built will be the perfect OEM replacement - 100% stock in form and function, just not with 25 year old wiring and broken connectors.

We had to find 1994-95 MAF, intake tube and other small parts to convert this car fully

We are trying out a new harness supplier, but they assured us it will be identical to an OEM 1995 Corvette harness and plug in, no issues. As long as it mimics the OEM harness and we use an OEM 1994 or 1995 ECM, this should be a zero-point change, as all 1992-1996 LT1 Corvettes are listed on the same line.

https://vorshlag.smugmug.com/Project...IMG_1355-S.jpg https://vorshlag.smugmug.com/Project...DSC_9422-S.jpg

The harness took a few hours to label the connectors (any emissions or cruise control related connectors will be removed, which again, is legal for TT-Letter) and disconnect everything all the way to the ECM and firewall, and even some bits that went down to the ZF 6-speed. We should hopefully see the replacement harness by the end of this week, which will give us just one week to get the engine dyno-tuned again before an upcoming track test at MSR-C on January 16th.

https://vorshlag.smugmug.com/Project...DSC_9424-S.jpg https://vorshlag.smugmug.com/Project...ette-LT1-S.jpg

That's what the engine bay looks like now, above left. The 1992 harness was been shipped off weeks ago (they have to re-use some connectors, which are not being made any longer) and it will look like the 1994-95 engine bay soon (above right). We already have an OEM replacement MAF and intake tubes, shown there. Luckily this 1994-95 stuff is available and not costly (new Delphi MAF was about $100).

I will show this all wrapped up and hopefully running well again in my next post.


Since this was only a partial update I'll have another that will show the completion of all of the above work (hopefully) posted after the next NASA event. That assumes a lot of things happen in a timely fashion over the next 2 weeks and that our test at an SCCA Club Trials event goes off without a hitch.

https://vorshlag.smugmug.com/Racing-...ckMap-CW-S.jpg http://vorshlag.smugmug.com/Racing-E...ortRanch-S.jpg


Sadly these were the only two tracks we ran the Corvette at last year, but we'll be hitting them back-to-back weekends in January 2016. This time the car will have a newly rebuilt engine, no fluid leaks, better engine and brake cooling, and hopefully some reliability. There were major issues with the C4 at both tracks in 2015 - a leaking rear seal at MSR-H kept us to 1-2 lap stints before we were black flagged, and oil smoke from a worn out engine kept getting the car black flagged at MSR-C in one lap or less. No more of that nonsense!

We ran a 1:43.7 lap at MSR-H in 2015 (still the TTC track record) and hope to better that by a good margin this year. We never got an official time in TT at the MSR-C event but, but I did run a 1:25.0 in the TT Warm-up session, which was my only complete lap of the weekend in that car. That was 2 seconds faster than the old TTC record at the time, but another TTC car reset the record on Sunday to a 1:24.424 (Mark Schnoerr's E36 M3). Hopefully #DangerZone can go quicker than those times at both tracks? The SCCA Club Trials event doesn't really have "classes", per se, but it will be a good practice for when NASA comes back to this track in March 12-13, 2016.

http://vorshlag.smugmug.com/Racing-E...P7B_7444-S.jpg http://vorshlag.smugmug.com/Racing-E...P7B_9962-S.jpg

That's all we have planned so far for the 2016 season - after the January SCCA and NASA track events we will see how we stack up in class for the year and go forward from there, either with refinement or possibly even changes to move to a new class (if the added TTC weight is a big hindrance). We will also have Amy's red 2001 BMW 330Ci at these two events, which is the new #JackDaniels TTD classed E46. For the C4 we have to have the rebuilt harness installed with a 1994-95 ECM (of course now there are none to be had, ugh!), the engine re-tuned to work with the 94-95 MAF, the Plexiglass rear hatch painted and latched, the front brake ducting wrapped up, and maybe some other small changes if there is time. Check back in a few weeks to see if some what happens...


Fair! 01-25-2016 03:42 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for January 22nd, 2016: Well the C4 has logged a successful test track day in 2016, where we tested a lot of big and small updates to this car (and a new BMW we're running in TTD this year). There was one fairly big change with Project #Dangerzone that we have been holding back - because, honestly, I didn't know if it would work. I will explain "the what, why and how" below. We also finished lots of little prep work to this car, installed the rebuilt wiring harness and 1995 ECM + MAF, got the stock rebuilt engine dyno'd (twice), added some tow hooks, fixed the front air dam, finished the brake cooling and rear Plexiglass hatch, lost some weight, and more.

https://vorshlag.smugmug.com/Project...DSC_9657-S.jpg https://vorshlag.smugmug.com/Project...DSC_9661-S.jpg

After my last thread update I was posting the above pictures on social media with captions like "almost finished" or "finally track ready". This was somewhat of a disinformation campaign, which might help me if I ever run for president, hehe. Gotta keep you guys guessing a little, but the big reveal is shown below. Let's get caught up...


In my last update I showed the slightly unfinished work on the lightweight polycarbonate rear hatch replacement. Shortly after I wrote that, our guys got it painted and installed and it looks good.

https://vorshlag.smugmug.com/Project...DSC_9589-S.jpg https://vorshlag.smugmug.com/Project...DSC_9591-S.jpg

The rear frame was made from thin wall 1/2" steel tubing, which is tricky to bend. This structure forms a frame that wraps around the back glass in 3 axis. Olof welded some tabs in place for the small diameter Quik-Latches that secure the bottom of the hinged rear glass, as well as tabs for the hinge mounts at the top.

https://vorshlag.smugmug.com/Project...DSC_9597-S.jpg https://vorshlag.smugmug.com/Project...DSC_9599-S.jpg

The mating pins for the Quik-Latch kits were installed in some simple brackets that Olof built and attached inside the rear of the hatch opening. Not only did the heavy 46 pound glass go away the big, electric solenoid operated, clunky steel latch mechanism also went away. The optional spring kits were added to the QuikLatches and that made them work a lot better. The rear frame was painted while hanging on a rack, and I snapped the pic in front of the LS1 Miata - which is about to get a big project thread update. We neglected to snap a picture of the final weight of the Plexi hatch and frame, but it looks like we lost 30-ish pounds - the new hatch is super light and much easier to lift.

https://vorshlag.smugmug.com/Project...DSC_9590-S.jpg https://vorshlag.smugmug.com/Project...DSC_9598-S.jpg

I had the guys paint the back of the plexi around a ~3" border, to give it an OEM look. Trust me, its worth the time and makes a helluva difference. Brad and Olof taped up and covered the area not to be painted then peeled the protective covering from the inside of the Plexiglass (both sides come covered in a protective film). The clear plastic was scuffed with ScotchBrite then cleaned and let dry. Then it was painted with two light coats of semi-flat black.

The painted hatch was then allowed to dry, after which time the frame was bolted to it on the inside and the QuikLatches installed. The frame was bolted to the factory hinge using the same stainless washers and flush head bolts we use on all Lexan window installs. The latches lined up and the spring poppers were added to the Quik-Latch assemblies.


You have to see it in person but the finished hatch looks really good. Going the extra yard to paint the border (on the inside) makes it look so clean and factory, covers up the steel tubular frame inside, and finishes off this mod well. The Quik Latches work great and we can access the rear hatch easily now (before you had to crawl through the back of the car and pull a cable - total PITA).


Updating the ECM and harness on this 1992 Corvette was the least fun part of this project to date. What a giant hassle, but the old 1992 computer can no longer haunt us, the engine runs now, and we learned a lot about the differences between the 1992-1997 LT1 engines & cars.

Just finding a used 1995 Corvette Engine Control Module proved to be difficult, as all of the sources we saw that had them in stock back in October had dried up. Lots of calls, emails, and finally the guys at True Street told me about a possible source. We paid too much ($315) and its a used ECM (not "reflowed" or rebuilt), but they do program the VIN # into the ECM for us and ... well... they had them in stock. Since it came pre-programmed at least it worked on their bench harness, which is a plus. The VATS would be turned off so the engine could run with our key, too.

https://vorshlag.smugmug.com/Project...DSC_9701-S.jpg https://vorshlag.smugmug.com/Project...DSC_9688-S.jpg

You can see how different the 1992 (left) and 1995 (right) ECMs look. This is why we needed to have the harness rebuilt - to fit this entirely different pin-out for the later model ECM.


Here you can see the Delphi replacement MAF (Mass Air Flow) sensor, which is part of the later 1994-96 Corvettes' EFI systems. The online resellers show the same stock replacement part from 1994-2001 Corvettes with prices from "cheap" to "not as cheap". These sensors have a "hot wire" that sits in the intake airflow path, voltage is applied to this, some wizardry is used, and the amount of airflow is measured more directly. The 1992-93 Corvettes used a "speed density" method of airflow measurement, where intake manifold pressure was used to infer the airflow. The MAF cars still use the old intake manifold pressure sensor, but use that data for fine tuning, not engine airflow measurement.

https://vorshlag.smugmug.com/Project...DSC_9596-S.jpg https://vorshlag.smugmug.com/Project...DSC_9658-S.jpg

New intake hose ends were needed on either side of the MAF sensor to connect it to the air box and throttle body. The sharp eyed among you might realize that these are not OEM replacement rubber bellows, so they aren't technically TTC legal without taking 1 point for an aftermarket "cold air". There's a reason why this doesn't matter that will soon become apparent.

https://vorshlag.smugmug.com/Project...DSC_9727-S.jpg https://vorshlag.smugmug.com/Project...DSC_9779-S.jpg

Going from the jumbled harness right out of the box at left to the completed and running engine harness install on the right took a few days, mostly chasing down "old car things". First it was the O2 sensors, which are different on the 95 vs the 92 (went to a heated, 4-wire O2 @ $29 each x 2). Then there was the IAC valve changes. The rebuilt harness was setup for the 95 Corvette computer and they updated the ends for all of the 1995 era sensors, too. Cheap, easy fix that will likely work better than the old 2-wire O2 sensors.

https://vorshlag.smugmug.com/Project...DSC_9719-S.jpg https://vorshlag.smugmug.com/Project...DSC_9720-S.jpg

Next was the computer itself, which had such a different shape that the (complicated) fiberglass bracket made to hold it was different. So Steve called up a salvage yard in Waco we know that keeps a lot of C4 Corvettes and he got this new bracket for $40, which arrived the next day. Could we have built one? Sure, but the shape and how it mounts was complicated enough that making one would have taken an hour or more, and every hour we're spending on this shop car is an hour we're missing out on customer work. $40 for the factory piece was the right move here. Remember: even though you can make something from scratch, doesn't mean that you always should.

https://vorshlag.smugmug.com/Project...DSC_9742-S.jpg https://vorshlag.smugmug.com/Project...O/DSC06284.jpg

Yet another "learning more about 25 year old LT1 engines" thing here - the Idle Air Control valve (IAC) is an electronically controlled device that meters air around the (closed) throttle blade, so the car can idle with your foot off the throttle pedal. GM changed the mounting shape and the 4-wire connector for the IAC from the 1992-93 LT1 cars to the later 1994-97 LT1 cars. The way the IAC mounts to the throttle body is via a small "manifold" (above right) that bolts underneath. As far as I can tell the throttle body didn't change much, so we just needed this 1994-97 IAC/coolant manifold, which bolted to our 1992 throttle body.

https://vorshlag.smugmug.com/Project...DSC_9753-S.jpg https://vorshlag.smugmug.com/Project...DSC_9754-S.jpg

After a full day searching we realized this part wasn't available new, and even Nook & Tranny was out of stock (they carry a lot of LS1 and LT1 stuff - helpful website for engine swappers). It was late in the day when we realized how scarce this manifold would be, and our Waco Corvette salvage yard was closed by then.

So we started looking for LT1 throttle bodies locally... my Facebook call-out was a miss but someone there suggested a junkyard here in town that had one for $50. So the next morning, the highlight of my birthday was trolling around in the bad part of town and grabbing up this 1996 Camaro throttle body. Ryan cleaned up then transferred over the IAC/coolant manifold and the new 1995 Corvette IAC ($53) to the 1992 throttle body and it was ready to fire. Curiously the shape of the throttle blade cable pivot cam was very different from the Camaro to the Corvette parts.


We've not had good tow hooks on this car, which is pretty short sighted for a track-only car. This is one of the first mods usually done to a race car, and we were lucky we never had to be flat towed in at the track, because there's not good places to latch a tow strap onto in this car. The front of this car is all plastic and there's nowhere good to bolt or mount a tow hook, so we had to get creative.

https://vorshlag.smugmug.com/Project...DSC_9700-S.jpg https://vorshlag.smugmug.com/Project...IMG_2003-S.jpg

We figured out on a previous C4 race car how well a roll cage mounted top tow hook works, for both winching a car into a trailer as well as for towing behind a wrecker. The top hook eye Ryan added to the cage also works as a great grab handle to winch yourself into the tight cabin of a C4. It will be easier to get into this car once I have sprung for a Quick Release and a real steering wheel, but for now this works great. Have already used this new hook to winch the car into and out of our trailer multiple times.

https://vorshlag.smugmug.com/Project...IMG_2001-S.jpg https://vorshlag.smugmug.com/Project...IMG_2017-S.jpg

Ryan also installed this roll cage mount "bus stop" mirror, a low cost convex mirror that lets you see into blind spots. We already have a 14" wide parabolic rear view mirror mounted in the cabin, but the right side factory door mirror broke decades ago, and the FIA cage tube on that side blocks my sight line to it anyway. This new spot mirror fills in the right side visibility gap from the side window to the high mounted rear view mirror perfectly. Bolted on in minutes and the old, dead door mirror housing was removed (less drag).

https://vorshlag.smugmug.com/Project...DSC_9594-S.jpg https://vorshlag.smugmug.com/Project...DSC_9645-S.jpg

The guys also got the final routing of the 3" brake duct cooling hoses nailed down. There's a number of zip ties that attach the hoses to moving suspension components, like the upper control arms. And some that hold them to fixed items inside the engine bay.


These hoses even clear the 335mm tires on 18x12" wheels up front at full lock, so they really got them tucked in there nicely. Oh yea... did I forget to mention the little wheel and tire upgrade??


What and why have we changed from the 245 R7 tire to a 335 front and 345 rear Hoosier A6?? Well let me try to explain. And remember, this was only a test - it might have been a complete disaster and I would have un-done the work and slapped the TTC legal 245s right back on.


Last year we only built this Corvette to run for one season as a "tweener car", after the TT3 Mustang was sold and before our next big crazy shop BMW V8 build was ready. Well we never started that big BMW build, which was delayed for multiple reasons. So this old 1992 Corvette was quickly shoved into the "fast shop car" role, with some planning that began last October.

https://vorshlag.smugmug.com/photos/...-MP7v3V3-S.jpg https://vorshlag.smugmug.com/photos/...-zJCCbXS-S.jpg

It also didn't make sense (to me) to have both of our shop cars in NASA TT Letter classes - the red BMW E46 330 in TTD and this white C4 Corvette in TTC. That's a little nuts. So back when we were looking at a TTD build for a BMW E46 coupe, we had already decided to move the Corvette out of TTC, or at least test some "big tire theories", with a wheel and tire upgrade to the C4 early in 2016.

https://vorshlag.smugmug.com/Project...DSC_9479-S.jpg https://vorshlag.smugmug.com/Project...DSC_9481-S.jpg

I suck at keeping surprises, and not sharing pictures of these wheels when they arrived and were initially tested was killing me. Just the 335 Hoosier tires were mocked up on the front (above) a few months back, but I couldn't share that either. These were some new A7s I had sitting around, winnings from the TT3 Mustang. We have half a dozen sets of scrubs, too.

continued below

Fair! 01-25-2016 03:43 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

While we started out thinking about just an 18x11" wheel and 315 tire (which would have fit under the stock fenders), the 335s fit so well under the stock fenders we measured the car for 18x12" wheels at both ends and pulled the trigger. 18x11 and 18x12 wheels cost the same, and I didn't have any (free) 315 tires laying around. So the 335/345 tire combo was chosen for... budget reasons??

https://vorshlag.smugmug.com/Project...DSC_9639-M.jpg https://vorshlag.smugmug.com/Project...IMG_1956-S.jpg

The easiest way to add a lot of performance to this TTC Corvette, since we had just had the engine rebuilt to painfully stock spec's, was adding mechanical grip. The easiest path I could think of was to add giant wheels and tires and dump some weight. So I started to do some TT1/2/3 calcs for this car late last season and it looked like TT2 would be a good goal. Here are our TT2 goals...
  • Goal Weight: 2850 empty, 3050 with driver
  • Goal P-to-W: 8.0 to 1 (TT2)
  • Goal power: 381 whp
So the 381 whp power goal? Yea, we're not close to that yet, and I will show our dyno tests below with the new motor. We have some things in mind but we figured it was worth testing this theory with the existing ~295 whp power level before we do any mods that could not be "undone", so we had a path back to TTC in mind if the first 2 events in 2016 were a total bust on the big tires.

This 2923 pound weight was with the full cage, 18x12" wheels, and half a tank of fuel. The car is still about 75 pounds too heavy

The TT2 class move was the reason for trying to lower the weight goal - and why we pushed ahead with the plexiglass rear hatch and snatched out the ballast box and multiple 45 pound weight plates. We still have some pounds to go on this 2850 pound goal (without driver), but there are plans to get there. I was just hoping we could get closer to this weight for the first event, and since we got the car down to 2840 pounds back with the 4-point roll bar, small wheels, and no rear hatch before.

https://vorshlag.smugmug.com/Project...B61G6929-S.jpg https://vorshlag.smugmug.com/Project...DSC_9630-S.jpg

If you have read my build threads over the years you know I like to use the biggest wheels and tires that can fit a car, for both road course or autocross use. One of the things our shop is known for is pushing the limits of wheel width under stock fenders on a number of cars: BMW E36, E46, E90, & 1M; EVO X, Subaru GR, S197 Mustang, C5 Corvette, and more. And now we can add C4 Corvette to that list. And maybe.... "fit" is a stretch here, I'll admit. But this car will get some flares soon to make it all look right and cut down on aero drag. We did learn what it takes to stuff a 315 and 18x11" under stock C4 fenders with this test, which is more usable data for most folks' cars.

https://vorshlag.smugmug.com/Project...DSC_9652-S.jpg https://vorshlag.smugmug.com/Project...DSC_9641-S.jpg

So as you can see the 18x12" front wheel we spec'd "fits" up front with no mods using the 335/30/18 Hoosier. This could work with zero mods for a street car with 11" wide wheels and a 315/30/18, but we wanted to go for broke so I decided on a 12" wide wheel and 335 tire up front. Again, we had so many sets of 335s and 345s from before. This worked so well up front on a 3600 pound TT3 Mustang that I figured it would work as well or better on a 2850 pound TT2 Corvette.

https://vorshlag.smugmug.com/TechArt...DSC_1013-S.jpg https://vorshlag.smugmug.com/TechArt...DSC_1011-S.jpg

The rear has an even bigger tire, the massive 345/35/18 Hoosier A7, used on an identical 18x12" wheel as the front. Yes, this tire should used a wider wheel, like a 13" or even 14" wide wheel. But the CF5 and F14 wheels from Forgestar top out at 12" widths in their 1-piece wheels. We wanted a less expensive set ($360/each) of wheels for this initial "big tire test", so we went with the same widths we used on the TT3 Mustang (18x12" front and rear). As you can see in the image above, the 18x12" wheel works with the 345 Hoosier... but it does have a hint of a squeeze. This is a 13.8" wide tire.

This was the fun "lets bolt the front on" test, before we had the wheels powder coated. Just one front 335 tire, tested quick, looked good. Dismount, take to the powder coater, and wait 6 days... Always waiting.


Back on January 14th, the crew here at Vorshlag had finally installed the rebuilt wiring harness (after 3 days of chasing down "changes") and the engine would crank and run... for 2 seconds. The folks who sold us the "1995 Corvette ECM" were supposed to turn off the security system in the computer (VATS), since our 1992 Corvette's key would be coded differently than the used ECM they sent us. They charged us a pretty penny ($315) for a used ECM, but part of that was "installing your VIN # and turning off VATS", and they were one of only a handful of shops that said they had a manual trans 1995 Corvette ECM in stock, too.

https://vorshlag.smugmug.com/Project...DSC_9775-S.jpg https://vorshlag.smugmug.com/Project...IMG_2002-S.jpg

Well of course that was bull. It was not in fact a Corvette ECM, but instead a 1994-95 Caprice or Camaro LT1 ECM, made for an automatic transmission. And they left the VATS system on, which was why the car won't run more than 2 seconds. But luckily the guys at True Street Motorsports know LT1s and using LT1edit they were able to convert the ECM to a 1995 Corvette manual trans unit with a reflash. They also reset the speedometer to work with the 345 tire we were going to use (not on the car at this point).

https://vorshlag.smugmug.com/Project...IMG_1998-S.jpg https://vorshlag.smugmug.com/Project...IMG_1988-S.jpg

The True Street guys fought with the ALDL port (the OBD port) for 5+ hours, calling the new wiring harness supplier (who I will never use again) and attempted some trouble shooting - since this port now didn't work. It worked before with the 1992 harness, but the $1000 custom built, 1992-to-1995 engine conversion harness they supplied seemed to have nothing but problems.

True Street had to overnight the LT1 "bench harness" for this style ECM, and remove the 1995 ECM from the car for each tuning iteration. With no ALDL port they couldn't data log during a tune, either, which made it even more difficult. The Corvette was stuck at their shop for 2 days and my tuning bill reflected the added work they spent chasing the harness problems. Oh well, live and learn... next time I'll use my standard "stand alone" wiring harness supplier and just punk on the factory gauges. We still lost the factory oil temp connection with this new harness, which is something I really wanted to be able to monitor.


Once the ECM was reflashed well enough where they could make a pull on the dyno, the ignition was apparently breaking up above 4500 rpm. You can see the jagged red dyno curve above, which is with the refreshed LT1 and 1995 ECM + MAF. This curve was beating the old stock LT1 and 1992 ECM tune (in blue) by 25 ft-lbs all the way to 4000 rpms, then it started to tank, then the curve went berserk at 4500.

Both of those dyno graphs are uncorrected, and the "301 whp" line was actually the "284 whp", once SAE corrected. Which is the tune we ran at the 2 NASA events last year. The newly refreshed but still painfully stock LT1 engine was pulling strong in the lower revs, but something wasn't right up top. Over 4500 rpms it wouldn't run. By this time it was nearly 2 pm on Friday, the day before the MSR event. I had to take it like it was, hope it was just an Optispark or spark plug problem, and see if we could fix it back at Vorshlag. I loaded up the car quickly and blasted back to the shop. We hadn't even fit the rear wheels yet and we had another car (BMW E46) to finish, too. Rough, nerve wracking day.

https://vorshlag.smugmug.com/Project...DSC_9802-S.jpg https://vorshlag.smugmug.com/Project...DSC_9804-S.jpg

As I raced back to the shop with the trailer full of Corvette, and I called our shop manager Brad and had him order spark plugs and water pump gaskets to be there in a few minutes. We unloaded the car and immediately started yanking the brand new OEM style Optispark, which was installed back in October when we were chasing the bad 1992 ECM problem. It was a vented, name brand, brand new unit with 0 miles on it. How could it be bad??

https://vorshlag.smugmug.com/Project...DSC_9806-S.jpg https://vorshlag.smugmug.com/Project...IMG_2011-S.jpg

Ryan swapped the nearly brand new spark plugs for a fresh set of NGK V-power plugs, and I had hoped one of the old plugs had a visibly broken tip or insulator (which would explain the dyno issue). Nope. The MSD billet Optispark distributor was pulled off in October, but it wasn't the problem, so now it went back on. Ryan and Brad thrashed with this while Olof and I worked on cutting the rear fenders to clear the 345s (see below) and Jon and Steve finished up the BMW 330 prep. It was an "all hands on deck" kind of afternoon.


The old MSD unit went in, the water pump went back on, the cooling system was refilled with distilled water and a splash of Redline water wetter, the engine was run, and the cooling system burped. Moments later we were cutting the front fenders and by 7 pm the car was loaded into the trailer. Fingers were crossed - there was no way to "feel" the ignition flutter until it was in 3rd or 4th gear, and it was pitch dark outside. I was not going to go blasting down the road with no lights to test this. We'd have to see if the MSD Opti fixed the 4500+ rpm issue the next day on track at MSR... if it didn't rain. Or snow. The weather was beautiful on this Friday, but predictions of COLD, wind, snow and rain were in the forecast for the next day. Yay. And MSR-Houston NASA event was the next weekend, 5 hours away... we needed to test the engine right NOW.


While the Optispark was going in, after the car returned from True Street on Friday, all four of the 18x12" wheels and a scrub set of 335F/345R tires were fitted to the C4. The fronts looked a little close to the hood for bump travel and the rears poked out a mile. Time to cut some fiberglass.

https://vorshlag.smugmug.com/Project...DSC_9801-S.jpg https://vorshlag.smugmug.com/Project...IMG_2005-S.jpg

Making the rears fit took a bit of fiberglass removal. First we laid down some green painters tape then I marked an "eyebrow cut" line, to give the rear some bump travel. At this point the tires stuck out about 1/2" but we would later see that we needed more like an inch of poke. Again, this is an identical 18x12" wheel as the front, and we planned up front to use a bit of spacer to make it fit out back. Long term, these 18x12's might all become front wheels, then we'll get the new M14.2 Forgestar 2-piece wheels out back in 18x13".

https://vorshlag.smugmug.com/Project...DSC_9796-S.jpg https://vorshlag.smugmug.com/Project...DSC_9798-S.jpg

Fiberglass dust is nasty stuff so we had Brad cutting and me or Olof with the vacuum sucking up the dust, and dust masks. Below right is the initial fit, then I went back with a 2" sanding disc and cleaned up the wheel arch a bit.

https://vorshlag.smugmug.com/Project...DSC_9799-S.jpg https://vorshlag.smugmug.com/Project...IMG_2012-S.jpg

The front wheel openings were also trimmed, very quickly. There was another "eyebrow cut" at the hood-to-wheel arch portion, just above the tire, to allow for bump travel. This happened right after an Optispark change was finished.


That's how it was loaded into the trailer at 7 pm Friday night. Yes, this looks a bit janky, but there was no time to make flares. We really just wanted to test this big wheel/tire combo on track to see if there was a prayer of TT2 competitiveness for later in the 2016 season.


I'm going to try to do this event coverage quickly, as it was only a 1 day event and we were just there to test the Corvette and BMW. I didn't really care how we finished, as this was really just an HPDE day that they were calling a "Club Trial" competition event. They had transponders but there weren't any classes, so they used a PAX factor to post "competition" times. Yes, an autocross PAX applied to road course times. I can't make this stuff up.

https://vorshlag.smugmug.com/photos/...-RSvn7P8-S.jpg https://vorshlag.smugmug.com/photos/...-8D44xLN-S.jpg

Anyway, we got there at 6 am, an hour before sunrise, and were working in the dark to have both cars ready before a 7 am driver's meeting. The C4 was unloaded, Amy and I did the wheel swap on her BMW, the AIM Solo lap timers were mounted, and we checked everything else we could under pitch black skies. The driver's meeting took a bit and after we got out, right as the sun was coming up, we greeted Brad and Olof from Vorshlag who had come to help. This became an eventful day of "track side car mods" so their assistance was most welcome.

The SCCA Club Racers had 25 entries spread across 5 run groups and Club Trials had 30 entries jammed into 1 run group. This is a 1.7 mile course and 30 cars spread out across a VAST array of skill and prep levels makes for a crowded track, but again - this was just a test for both cars.

https://vorshlag.smugmug.com/photos/...-zJCCbXS-S.jpg https://vorshlag.smugmug.com/photos/...-DTk8Z2S-S.jpg

They gridded the C4 in P1 and stuck Amy about a 1/4 of the way down the order. We went out into the first session and it was COLD with 40 degree temps and 20 mph winds all day. I could hear all sorts of tire rub on the out lap so I got the heck out of the way and dove into the pits before I held anyone up. But more importantly, I was able to test out 3rd and 4th gear under load. NO MORE OPTISPARK ISSUE! Engine ran strong all the way to 6000, so that's already a win. But getting no laps meant I'd be stuck at the back of the pack, which sucked.

https://vorshlag.smugmug.com/photos/...-sVvKx62-S.jpg https://vorshlag.smugmug.com/photos/...-ZsCm9zd-S.jpg

Amy drove the whole session in the BMW with the rear tires rubbing the rear fenders badly, sending up plumes of tire smoke. Did she stop? No, the ran the whole session. Oh well, if she ruins her tires its her own fault. The Bilstein PSS coilovers were sprung too softly and allowed a TON of body roll, so we'd be doing a big spring rate upgrade immediately after this event.

continued below

Fair! 01-25-2016 03:46 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

https://vorshlag.smugmug.com/photos/...-J9wZgQN-S.jpg https://vorshlag.smugmug.com/photos/...-JnpCjnm-S.jpg

The fix for the rear tire rub on the C4 was to add more rear wheel spacer. We had all the spacers in the trailer stacked to make nearly a 1" spacer, which moved the rear wheels outboard enough to rub less on the inner fender sections. See why I wanted the long ARP wheel studs? Getting no lap time for the C4 put me at the back of the grid for session 2, right next to Mark Council's C5. His transponder didn't work so he got no times, either. So the two of us went from P1 and P2 on grid to P29 and P30.


Mark's C5's 4th gear synchro let go right in front of me at the beginning of Session 2 (its already getting a C6 Z06 trans installed at our shop), but I went around him and started picking off cars on every straight. The rear was very bouncy - stock shocks aren't made to deal with 345 Hoosier A6 tires! - but I could drive around it. We're going to need to massively increase rear spring rate and put some real shocks on this car if we keep the big tire setup.

https://vorshlag.smugmug.com/photos/...-2Fgfzcm-S.jpg https://vorshlag.smugmug.com/photos/...-vgpZRjQ-S.jpg

So there were lots of spins and traffic in session 2, and I spent the entire time passing slower traffic, but I did manage to get a quick enough time (1:27.9) to move me to P8 on grid for session 3. The C4 also made 5 laps - in a row - which I haven't ever done in this car. This is already a successful test.

https://vorshlag.smugmug.com/photos/...-vJQcMCt-S.jpg https://vorshlag.smugmug.com/photos/...-wmJ7mqC-S.jpg

In session 3 the C4 was passing cars pretty quickly and I managed to lap some other folks 2-3 times in this session. The weather was holding so far (no rain yet) but it was still bitterly cold. Amy's 330 had gone through two different fender rolling jobs in the pits by now, which was a giant PITA.

https://vorshlag.smugmug.com/photos/...-HCsrB3m-S.jpg https://vorshlag.smugmug.com/photos/...-TQsS22d-S.jpg
Track side fender rolling sucks - this should always be done in the shop! - but parts delays & C4 prep ruined our schedule on the E46

I found a new issue at the end of session 3 - the brakes went away after 6 laps. There was NO pedal at all. WTF? I wasn't even pushing the brakes that hard, and we had added the brake cooling up front. Fresh XP20 Carbotech pads, new Centric 13" rotors and Motul 660 fluid should have lasted longer than that. The cornering speeds were way up on the big tires, so I was going down the straights faster, but nothing like we did in the TT3 Mustang (this C4 feels like it has less than 300 whp - come to find out later, it does). You can see this at the end of the 4 minute video, linked below.


After I lost the brakes I dove into the pits, limped it through paddock and barely got it stopped in front of our trailer after pumping the brakes many times. Brad and I bled the brakes, which already had Motul RBF660 and almost no laps on the fluid. A little air in the right rear but a LOT in the left front (that's a clue). The new front brake calipers had less than 10 total laps on them. The AP caliper temp indicator strips didn't show much heat in any of the calipers, but the left front was a tick higher at 370°F (the other 3 calipers barely registered on the strips). That temp shouldn't boil Motul 660? Maybe the fluid had been in there so long it had absorbed water? Oh well, it was fresh after a full system bleed.

https://vorshlag.smugmug.com/Project...DSC_9824-S.jpg https://vorshlag.smugmug.com/photos/...-BtJFXfn-S.jpg

With a quick time I was gridded P1 in session 4, but it started to rain before we went out. Oh great, giant slick tires and I don't even know if the wipers work! I was going to just make some laps in the wet and test the brakes again. I let the C5 Corvette gridded P2 go around me at the start, as the old Hoosiers take a lap or two to get up to temp, but I reeled that car in and we both caught the back of the field at the end of the first hot lap. Like I said, big discrepancies in lap times in this large 30 car field, spread out on the short 1.7 mi course.

After a number of passes I got little bursts of clear track, and the rain wasn't much more than a sprinkle. I was gaining confidence in this janky test setup more and more, taking corners faster, braking less and less for the high speed sweepers like Big Bend and Ricochet. I was almost feeling like I could take come of these fast corners with the throttle matted.... almost.

https://vorshlag.smugmug.com/photos/...-x5XfM9C-S.jpg https://vorshlag.smugmug.com/photos/...-ZD7Gz7t-S.jpg

Again, after 7 laps of mostly traffic, the brakes went away abruptly. No hints, not softness creeping into the pedal, instantly gone. Just nothing there. At all. Luckily I was held up behind a BMW for most of a lap and had backed off to about 50%, trying to build a gap. When I sped up to take lap 8 at speed, going into Big Bend, I went to touch the brakes... FLOOR! Nothing. Well luckily there was some "grip reserve" and I was able to take Big Bend without any braking whatsoever, hehe.


I dove into Pit In, downshifted a few times to slow down, then crawled to the paddock in 1st gear. I pumped the brakes furiously, nothing. Had to shut off the motor with the car in gear in the pits to get the car to stop, or else run into the back of the trailer. Yikes. Glad I did that session to test the freshly bled brakes, since this is not the fluid boiling. Something else is going wrong. We let the car cool off, winched the Corvette into the trailer, swapped wheels for Amy's BMW so she could drive it home, and got out of there before the rain got any worse.

https://vorshlag.smugmug.com/photos/...-FF6jwLJ-M.jpg https://vorshlag.smugmug.com/photos/...-4XcTQGS-M.jpg
Raw time results from session 3 (dry) and session 4 (wet). DangerZone was quickest of the day?

The C4 was once again fastest in "moist" session 4, and only a 1/2 second off my dry session 3 times. Again, I was still learning the car and this new "big tire setup". The 1:23 lap times aren't all that impressive on their own, as we've run 1:17s in the TT3 Mustang here - but we did that in much warmer weather. This January weather was brutally cold and the other racers were commenting that their times were 2-3 seconds off the mark. Whatever, don't care much about lap times this day - this was still a productive test for both cars and we learned a lot.

I came away from this test feeling... cautiously optimistic? Some of the folks here would be at the NASA TT event the following weekend, so I could compare to them there. This was the first time to really put laps on the new springs and rebuilt shocks - the front felt pretty planted (1170 #/in custom transverse spring by VBP) but the rear didn't feel good at all (510 #/in stock '84 Corvette Z51 rear spring). There was a lot of rear suspension "wallowing" that had me a bit concerned. MSR-Cresson is notoriously VERY SMOOTH and the back still felt unsettled. How would this work at MSR-Houston, which is much bumpier in sections? Could the rebuilt but still stock dampers handle the added grip from the 345mm A6 tires? Are the 25 year old, rotted rubber suspension bushings going to bite us now with the bigger grip? We would see in a week...


We unloaded the C4 on Monday morning and took a closer look at the caliper temp strips and the tire rub evidence. Wow, the rears really self-clearanced the fender liners. The most damage was done on the very first lap in session 1, where the inside rear sidewall on the right rear dug into a suspension bracket (see below), which cut a groove into the edge of the tread. This initial rubbing was why we added more spacer and swapped the rear tires side to side. We kept an eye on this tire all day at MSR-Cresson - the groove never worsened - but this tire will still be thrown away and never used again.

https://vorshlag.smugmug.com/Project...DSC_9830-S.jpg https://vorshlag.smugmug.com/Project...DSC_9827-S.jpg

The calipers barely even registered any heat at all, so the brake cooling wasn't the issue. Ryan and Brad tried to re-bleed the brakes but it never got better - car had "no pedal". This meant we had a bad master cylinder. I made some calls and the previous owner of this C4 (Matteucci) mentioned that he had replaced the master cylinder once already (installing a reman 96 model). We also noted that another C4 customer in the past had gone through 2 or 3 masters as well. Its back to "old car problems" again - a freshly rebuilt master cylinder for a 1996 model (which ensures we get one valved for the 13" front brakes) was ordered.

We also scheduled a dyno pull at True Street, to get the legal pair of SAE corrected dyno pulls for TT1/TT2 classing. I thought briefly about running TT3, where this car should really be classed (for it's P-to-W and lack of aero), but we wanted to hopefully stay in the same class for the entire year for this car, and I really wanted to add aero and more power now that the "big tire test" seemed to be successful. And why run TT3 again, when we had already run that class successfully for 3 years in the Mustang?

https://vorshlag.smugmug.com/Project...IMG_2049-S.jpg https://vorshlag.smugmug.com/Project...IMG_2048-S.jpg

True Street squeezed us in Tuesday morning (1/19/16) so we loaded up the C4 (with non-functional brakes) Monday night and I took the car there first thing on the morning of the 19th. The C4 was strapped down with the correct sized tires (first dyno test on the 345 Hoosiers, which will sap a little more power than the 245s) and after the engine was warmed up Sean made two dyno pulls in 4th gear on their DynoJet in-ground chassis dyno. Temps were in the low 40°F range, so there were bigger than normal correction factors.

https://vorshlag.smugmug.com/Project...D-011916-S.jpg https://vorshlag.smugmug.com/Project...E-011916-S.jpg

The best it made was 296 whp and 363 wtq, using the common STD corrections. That translated to 288 whp/354 wtq with the SAE correction factor that NASA wants to see. Hmm, we've got a long way to go to make 380 whp for TT2, but that is a battle for another day. The dyno curve was smooth and looked remarkably similar to the bone stock 284 whp dyno curve done in January of 2015, but there's a solid 20-25 wtq bump from the bottom to around 4000 rpm, then the new motor seems to choke out and make nearly the same peak power number as before (284 whp then vs 287 whp now, both SAE).

Of course there's a restriction somewhere - either the anemic 1992 LT1 camshaft, the stock throttle body, the smallish MAF sensor, the stock catalysts, or the stock exhaust manifolds are choking the life out of this engine, but 296 whp is pretty normal for a stock LT1 with a super light flywheel. Remember, this car's 7.25" multi-disc clutch/pp/flywheel is a solid 50 pounds lighter than stock, which all translates to more engine acceleration, which adds power on a dyno - even if its kind of fake.

ARH makes C4 headers in 1-3/4" and stepped 1-3/4" to 1-7/8" primary long tubes, with an X-merge, with and without cats

For TT1/2/3 we can do damn near anything we want to add more power - heads & cam, crazy exhaust mods, an LS1 swap, turbos, you name it - but we'll look at a long tube header & freer flowing exhaust upgrade first, then see where we are on the dyno. The ARH long tubes for the C4 (see above) should add 30 whp by themselves, if not more. We'll ditch the 25 year old catalysts and the choked up after-cat system, which should add another 10-15 whp. So look for power upgrades to be added and tested throughout the 2016 season, if things work out with DangerZone in TT2.

https://vorshlag.smugmug.com/Project...DSC_9839-S.jpg https://vorshlag.smugmug.com/Project...DSC_9826-S.jpg

After the two quick dyno pulls I loaded the car back up and got it back to the Vorshlag shop. Ryan quickly installed a new 1996 master cylinder and - viola! - the brake pedal is back. He also checked the car stem to stern for a pre-track inspection - nut and bolting everything, fixing some fender structure that had worn through, etc. They did an oil and filter change, going from dyno based high zinc "break-in" oil for the new engine, to 15W50 Mobil1 synthetic for the next 2 race weekends.

https://vorshlag.smugmug.com/Project...DSC_9919-S.jpg https://vorshlag.smugmug.com/Project...DSC_9918-S.jpg

The crew also fabricated the rear tow hook, shown above. This bolts to the rear aluminum crash beam, which is pretty beefy - we should lighten that the next time the rear bumper cover is off (bumper cover is a total MOFO to remove - takes 2-3 hours, with small hands). This rear hook has a 2" inner ring, which is the required size by NASA and SCCA. Just nice to know its back there, if I nose this thing into the weeds and need a tow. Hopefully it will never be used.

https://vorshlag.smugmug.com/Project...DSC_9721-S.jpg https://vorshlag.smugmug.com/Project...DSC_9843-S.jpg

The past 25+ years haven't been kind to the front air dam plastics, which were falling off and damaged when we got the car. One piece was held on with about 6 pounds of Gorilla Glue! The low ride height and shorter 245/40/17 tires we ran last year made this worse. Now that the car is sitting up a bit higher on the taller 335/345 tires it was time to swap on the new GM plastic pieces. Ryan had to reconstruct much of the support structure on the left (and scrape off the Gorilla snot) but he got them all on and aligned correctly. These pieces help force air into the "bottom feeder" radiator air intake, plus keeps some air from going underneath the car (reducing lift).


I was going to wait and include the write-up for the upcoming NASA event at MSR-Houston in this update, but it is already running long, so we'll cut it off here. Here is the first third of the NASA Texas 2016 schedule:
  • January 17-18 – MSR-Houston, Clockwise
  • March 14-15 – MSR-Cresson (the 1.7 if we have less than 34 cars in TT, or the 3.1 if we have more)
  • April 25-26 – TWS

Obviously we're taking the C4 in TT2 (and the E46 in TTD) to this weekend's NASA event. The TT2 competition signed up already looks brutal - 10 registered in class, including several Z06 Corvettes, a Porsche GT3, a race prepped EVO, and more. So yea, DangerZone might not pose much danger to the class right now. We're under powered for TT2 by about 100 whp, the rear spring rates are all wrong, and the shocks are laughably inappropriate for these tires.


So this first NASA event at MSR-Houston will be a "let's just get points" opportunity and more shake-down runs for this new "big tire" setup. I'm not even going to burn the set of Sticker tires here, since we'll be pretty far off the TT2 pace. Amy has one other TTD competitor so I'll try to help her do her best, but that car is also under-prepped for the class at this point. First event of the year - we both need a lot of luck to score points here, which might help us later in the season.

Until next time,

Fair! 03-25-2016 08:38 AM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for March 25, 2016: When we last left off the C4 had been raced once at MSR-Cresson and set FTD for the SCCA Club Trials. There were some issues with the brakes, and the shocks didn't deal with the minor bumps at Cresson, both of which gave me pause... but I ignored that and pushed forward on the "Big Tire" TT2 plan. We did some quick fixes to the brakes, then went to with NASA at MSR-Houston, one week later. After that we had a little time, so we made some changes and ran another event with NASA in March, back at MSR-Cresson again. We played a bit of "musical chairs" this time, but I will explain the what, why and how below.


My last forum build thread post ran long and I left a few things out due to space. While I was writing the last few bits of that post, a few extra changes were being added before the January MSR-H NASA event, which I will go back and show below.

https://vorshlag.smugmug.com/Project...B61G7493-S.jpg https://vorshlag.smugmug.com/Project...DSC_9884-S.jpg

For the first "Big Tire" test at MSR-Cresson we had stacked up a bunch of smaller spacers on the rear wheels. We had spec'd these custom 18x12" wheels to actually fit the front with a 335mm tire, hoping that in the near future we would buy some wider 3-piece rear wheels (18x13"?) for the massive 13.8" wide 345/35/18 Hoosiers. If that happened then all four 18x12's we built the same way could become front wheels, leaving us with two full sets of race wheels again. Its always smart to have a full back up set of matching race wheels, so you can practice on your "old scrubs" and save the sticker set of tires for that "golden session" of the weekend.

To make these "fronts" fit out back for now we just used a couple of small spacers. During this January SCCA Club Trials event they rubbed inboard with the 345s, especially in hard corners, so we kept stacking more spacers out back until the rubbing stopped. The result was we were left with a LOT of tire poke at the rear (which I detest), but we were going to cover all this with custom built flares later, so I wasn't too worried. As long as the car still fit inside the trailer (it did, easily) it wasn't too wide. More track width adds mechanical grip, and since this wasn't an autocross car, the added width wasn't going to "kill the slaloms".

https://vorshlag.smugmug.com/Project...DSC_9881-S.jpg https://vorshlag.smugmug.com/Project...DSC_9883-S.jpg

After this event, back at our shop I removed a rear wheel and measured "the stack" of spacers. I took this measurement and found 1-piece hub-centric spacer for use at the next event. This would be safer and less janky than a bunch of mis-matched spacers stacked up. I found .875" thick aluminum spacers from Bear Racing - the pair is shown above on the scale. These 1-piece spacers fit the hub bore and bolt circle of the C4 perfectly. I'll talk about how these were re-purposed later in this thread...

https://vorshlag.smugmug.com/Project...DSC_9868-S.jpg https://vorshlag.smugmug.com/Project...DSC_0444-S.jpg

I forgot to show in my last post where Jon was adding new graphics for the move to TT2, as well as a few other new decals for Forgestar and the "Rampage" rear license plate. These are made on our 24" wide vinyl plotter, shown at right. Nothing fancy but it works well enough for simple graphics for our shop cars and a few customer cars we maintain at the shop.


Another thing that I had always meant to do to this car, even when it was in TTC (we had taken points for it), was open up the factory LT1 "air box". As you can see above, the intake manifold is fed by a rubber tube (now with a MAF sensor added) from an air filter "enclosure", or air box as we like to call it. By the way, there is no direct path for air to get into this semi-sealed area ahead of the radiator inlet duct. Air just bleeds around and through gaps in the bodywork to feed this area. We can (and eventually will) add a "ram air" inlet on the front of the car (front license plate pocket lines right up) to feed the air box with a good high pressure source of fresh air. For now I just wanted to open up the factory air inlet hole and remove the air baffle on the front of the air box.

https://vorshlag.smugmug.com/Project...DSC_9861-S.jpg https://vorshlag.smugmug.com/Project...DSC_9862-S.jpg

Above at left is the unmodified factory airbox, which holds a pleated paper air filter and has a baffle on front - to cut down on noise and to keep the filter from getting wet. The "quietness" of this car doesn't matter to us now, nor does a little moisture from running in the wet (we don't even have real "wet" race tires, so if rain is falling this car isn't likely running). Getting more air into this choked up airbox was the goal. In stock form all of the air flows in through a single rectangular hole, after it travels through a plastic air baffle - which is shown above at right, already removed.

https://vorshlag.smugmug.com/Project...DSC_9863-S.jpg https://vorshlag.smugmug.com/Project...DSC_9864-S.jpg

The real fabricators in our shop were busy on billable customer work so I hacked up the airbox myself, after we were closed one day. First thing I did was drill out the rivet heads to remove the air baffle. Then I scribed out two new rectangular openings on each side of the factory hole. This was done quick and dirty, with just a few measurements and a straight edge. I marked, center punched, then drilled some holes in each corner to make the new openings have rounded corners, to try to match the OEM hole. Then I used a small jig saw to join the drilled holes. End result was two new rectangular openings with rounded corners.

https://vorshlag.smugmug.com/Project...DSC_9872-S.jpg https://vorshlag.smugmug.com/Project...DSC_9873-S.jpg

For being 25 years old the air box was in great shape. After the 2 new openings were cut, and the edges deburred and sanded smooth, it was ready to prep for paint. I scuffed the painted metal with some Scotch Brite pads and cleaned everything with wax and grease remover. Once that dried it was hit with 3 light coats of black paint.


This is the final result, above. I may have rushed the drying of the cleaning solvent, as the paint fish-eyed in some sports. Oh well, its hard to even see this air box with the clam shell hood up. More importantly - the baffle was gone and the surface area of the opening in the airbox more than tripled.

https://vorshlag.smugmug.com/Project...DSC_9879-S.jpg https://vorshlag.smugmug.com/Project...DSC_9878-S.jpg

We looked at some aftermarket "cold air" kits for the LT1 C4 and the few choices still available were not very appealing. Sure, we should add a more direct path of fresh air from the front bumper to this now opened up enclosure, but for now it was a $3 upgrade (cost of paint) that was well worth the hour it took me to do. There is indeed more intake noise, so maybe there would be a tick more power on hand for the MSR-Houston event? I'd be running nearly 100 whp down on what a real TT2 car at this weight should be, so anything would help.


One last little update. After the January SCCA Club Trials, when the brakes failed in two sessions, we replaced the brake master cylinder with another reman unit (we cannot find new master cylinders for this car). This might be the 3rd or 4th reman'd MC this car has seen, but when it was installed and bled the pedal pressure felt right once again. Let's see how long this one lasts? As with all track cars we build, the cap to the plastic fluid reservoir got wrapped with a shop towel and zip tie, which usually soaks up the small amount of fluid that might puke past the cap under high temps. The original vacuum assist brake booster is still on the car - and its a PLASTIC unit that is a known failure point. More on that in a bit.


The MSR-Houston track is not nearly as smooth as MSR-C, but that thought never entered my mind before we got here. Why? I've always raced cars here with GOOD monotube adjustable coilovers, so it never felt bumpy in the 7-8 times I'd raced here before. Boy was I in for a surprise in #DangerZone!

We took both the Corvette and BMW to this 2016 NASA season opener event at MSR-Houston. We loaded up Friday morning and slogged through 6.5 hours of driving, most of which was burned inside the city limits of Houston dealing with their nightmarish traffic (normally this is a 4 hour drive from Dallas). I was towing our enclosed trailer with the Corvette inside and Amy drove the TTD classed BMW 330 down.

https://vorshlag.smugmug.com/Racing-...ckMap-CW-S.jpg https://vorshlag.smugmug.com/Racing-...IMG_2068-S.jpg

When we arrived it was pitch dark and the paddock was packed. We got lucky and found a wedge shaped spot close to grid where we unhooked the trailer and parked the BMW. Amy had Tech inspect the BMW for Annual TT Tech and a new Logbook.

https://vorshlag.smugmug.com/Racing-...IMG_2102-S.jpg https://vorshlag.smugmug.com/Racing-...IMG_2110-S.jpg

It was too dark and too late to extract the Corvette and make the close of tech that night, so we got to the track early Saturday morning to take it through annual tech before the first TT session. Well, in the rush we did not put the safety wire into the Schroth harness clips in the C4. Without it, we could not pass tech. I pulled out of line, went back to paddock and added the safety wire to "lock" the clip-in latches closed. I got back in line to re-tech but the TT field had already gone out on track. I got my tech sticker, drove straight to grid, belted up and went out on track.


They threw the checker as I came around on my warm up lap so I didn't get a time. This meant I'd be starting from the back of the grid, which makes for an extra challenge. I was also trying to drive BOTH of our TT cars both days, so I had my hands full.

https://vorshlag.smugmug.com/Racing-...YD2H3893-S.jpg https://vorshlag.smugmug.com/Racing-...YD2H0844-S.jpg

This was the debut NASA event for our BMW E46, which we had planned on running in TTD for 2016. We're doing a "build progression", with parts being added along a set build plan, hopefully showing incremental improvements along the way and testing products we make or want to offer. So at this event the BMW was PAINFULLY under prepped (150 pounds over weight + 50 whp down). Unfortunately, the Corvette was also very under-prepped for TT2.

We had a little bit of a break after the first "warm-up" TT session, which is only used to get times for the gridding of cars in the first "official" TT session. So I had no time in the TT2 Corvette and gridded at the back in this next session. I went out on track hoping to get the tires up to temp by lap 2 or 3. That ended up never being an issue - even when "cold" these massive A6 Hoosiers make MONSTER GRIP. Lots of people think that if a tire isn't at its peak temperature that it will have zero grip. That was NOT THE CASE in this car... it made TOO MUCH grip from the very start.

Event Photo Gallery: https://vorshlag.smugmug.com/Racing-...A-MSRH-012316/

The massive mechanical grip plus the bumpiness of this course added up to one of the scariest laps Ive driven in my 29 years of experience with track events. There is a straight section of this course between T14 and T13, right before the hill you almost jump they call "the launch", which was especially bumpy. I had to back off a lot here just to stay on the track. I have never noticed the bumpiness there in any previous car I've driven at this course, or in our BMW this same day, all of which had been on proper shocks. Driving this track in the C4 was a "life altering experience". After a couple of laps and almost skidding off the track going in a straight line I pulled into the grid, white as a ghost.

That. Was. Not. Fun.

https://vorshlag.smugmug.com/Racing-...YD2H2443-S.jpg https://vorshlag.smugmug.com/Racing-...YD2H0154-S.jpg

I realized, right then and there, that this Big Tire test was a terrible idea without buying real dampers and changing some other components. Adding 100mm of tire, and going from an R7 to an A6 compound, showed the true limits of the 25 year old Delco Bilsteins. I had run this track the year before in this same car on the little 245s to the tune of 1:43.7 without any handling drama... this day on 335/345mm tires I could barely manage a 1:48.9 with a fresh motor and many other upgrades.

continued below

Fair! 03-25-2016 08:39 AM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Continued from above

Five seconds slower, just from lack of control. It wasn't "more rolling resistance" or "not enough heat in the tires", no the cause was "bouncing off the bump stops" with an uncontrolled suspension setup. The GRIP was definitely there, but I simply couldn't use it when the track got bumpy.

https://vorshlag.smugmug.com/Racing-...IMG_2070-S.jpg https://vorshlag.smugmug.com/Racing-...IMG_2069-S.jpg

I parked the C4 and ran the two remaining TT sessions in the BMW, where we had a shot at winning TTD class. And we did win on Saturday, but it was close. The C4 was WAY back in the TT2 standings from this lone session with 2 hot laps.

https://vorshlag.smugmug.com/Racing-...IMG_2089-M.jpg https://vorshlag.smugmug.com/Racing-...IMG_2092-S.jpg

Good party Saturday night, but it was cold all day and into that night. It was 32°F in the morning, got up to the low 40°F temps during the afternoon, but the wind never let up and we were always cold Saturday. The track did warm up enough to put some quicker TT times down at the end of the day.

https://vorshlag.smugmug.com/Racing-...IMG_2093-S.jpg https://vorshlag.smugmug.com/Racing-...DSC_0032-S.jpg

It was foggy, humid and damp for the first TT session but I wanted to get another lap in the C4 out of the way, so I ran that car first. I finally put the vidcam in, dried off the dew inside the windshield and back glass (we really need a defroster in this car), and lined up in 18th out of 38 on the grid for TT Session 1.

Click here for in-car video of the bumpiest, scariest lap around MSR-H

After getting out of traffic on the first lap I made one hot lap and ran a 1:46.991, quicker than I drove Saturday, but still 3 seconds off my 2015 TTC lap record on the little tires. The lap was still very sketchy, bouncing around like crazy. You can hear me comment on the video with things like "Wow, that was scary" after Turn 13. The rear suspension was hitting down on the bump stops and going up to full droop... it was much worse inside the car than the video shows.

https://vorshlag.smugmug.com/Racing-...DSC_0042-S.jpg https://vorshlag.smugmug.com/Racing-...DSC_0037-S.jpg
With the same minimal safety requirements as HPDE, there are stark differences in safety gear used in TT cars

As I came around the last turn on the lap shown above there was a C5 parked in the middle of the track, right under the Start/Finish stand. It had just backed into the pit wall hard and was totaled. The driver is lucky to be uninjured - he was using nothing more than a helmet, stock seats and stock 3-point belts. I had to back off and pull off line to miss the car (it happened only seconds before I got there, and there was not a yellow at the previous corner station yet). Made me appreciate our decision to fully cage the C4 and invest in a HANS and other safety gear. And made me rethink letting Amy out in her TTD BMW with none of these things, too.

https://vorshlag.smugmug.com/Racing-...IMG_2095-S.jpg https://vorshlag.smugmug.com/Racing-...IMG_2094-S.jpg

I am posting pics of the crashed TT car to share what can happen to people at any track event, if things go very wrong. I hope that maybe some folks will have that "light bulb" moment after seeing this and upgrade their personal safety gear. /off soap box


Once again, after the first TT session in the Corvette that day, I came in and parked it. Nothing had improved magically overnight and it was still way under damped for these tires, springs and track surface. Everything was moving around, uncontrolled, and I recommend you NEVER do this. The sad thing is that I knew better, damn it. I might should have gone with smaller 315s and of course spent the money on REAL shocks before trying this test. I just got greedy!

With fielding 2 track cars this year, a business to run, and coming out of our slowest time of the year I just couldn't afford the $4500+ in dampers and springs and bushings that these tires demanded. It was a gamble but it didn't pay off. Running these big, sticky tires on 25 year old shocks was flat out dangerous. #DangerZone was supposed to be a joke, not a real motto!

https://vorshlag.smugmug.com/Racing-...YD2H2704-S.jpg https://vorshlag.smugmug.com/Racing-...YD2H1080-S.jpg

Parking the C4 for the day freed me up to be able to ride right seat with Amy (above left) in an HPDE3/4 session, to try to instruct a bit and get her confidence up. In just a few laps she had found 2.5 seconds (it was all in the braking zones) and was back in the TT fight. It felt good seeing that big of a time change just by giving her a few pointers. I might actually try to Instruct with NASA again... I kind of miss it.

I ran the BMW in 2 more TT sessions (2 and 3) mired in traffic, but I had what I thought was a healthy lead in TTD towards the end of Sunday so I let Amy drive the E46 in the 4th TT session... and sure enough, her BRZ competitor in TTD found a bunch of time and got the win on day 2. Oh well, we still have a LOT of work to do on this Bimmer.

https://vorshlag.smugmug.com/Racing-...at-final-S.jpg https://vorshlag.smugmug.com/Racing-...un-final-S.jpg
Left: On Saturday the C4 was 6th in TT2, 330 was 1st in TTD. Right: On Sunday the C4 was again 6th in TT2, 330 was 2nd in TTD

This race weekend was a mixed success. The up-classed TT2 Corvette was way off the pace for both the class and the times I had driven here last year in TTC. That car took 6th out of 10 in TT2 on day 1 and the had same finish position on day 2. While the suspension setup was a bust, at least it ran reliably, was leak free, and the rebuilt engine never skipped a beat or blew any smoke. The BMW 330 was also a bit off the pace of the old TTD track record (1:48.4), but it did OK for such limited prep in its debut event, with one 1st and one 2nd place finish for the weekend.

Hey.... we don't need TWO Archer themed Corvettes, hah

We learned plenty at this event and still had a LOT of fun - seeing friends, the Saturday night NASA party, and both of us getting plenty of seat time in the BMW. The dismal results in the C4 made me rethink this new direction for Project #DangerZone.


After the shellacking I took at MSR-Houston, we had nearly 2 months to think about the C4 would need to do to make it a more competitive (and safe) TT2 entry. I started adding up the cost of parts and the work it would need:
  • $4500-5500 in MCS doubles, springs, and Vorshlag spherical top mounts
  • New Delrin/Poly/spherical bushings at every suspension pivot location
  • A new set of heads, camshaft and valvetrain upgrade, maybe a new intake manifold (to his 380 whp)
  • Full length headers, custom exhaust, and a better tune (to his 380 whp)
  • Custom flares at all 4 corners
  • Splitter, big wing, ducted hood for some downforce
  • Thermostatically controlled oil cooler, Accusump, and other oiling system upgrades
  • Aftermarket carbon fiber hood ($3000) to lose more weight

The list kept going beyond this, which was long after my budget gave up. These numbers just didn't make sense a car we really don't make any parts for, that is based on 33 year old chassis, and with a motor I had just spent several thousand dollars to have rebuilt to painfully stock specs. What was the purpose of this TT2 class move? Just to have "faster lap times", but yet give class competitiveness or require a LOT more money to handle as well on the big tires? Deep thoughts.


We kicked around some ideas internally and on Corner-Carvers about an LS swap, but the hours and cost projections kept spiraling out of control. This C4 was supposed to just be our "tweener" build, done on a tight budget, to bridge the gap between our TT3 Mustang and the Next Big Shop Build. Now we were talking about a $40K+ showcase car... that was based on a vintage chassis? This didn't really reflect what we do at our shop, and was the epitome of bad judgement, so I went through the Pros and Cons for a week or two.

Meanwhile I asked our crew to look into a couple of small fluid leaks that I only noticed in the trailer coming back from the MSR-H event. First fix was building a power steering catch can, shown above. The pump was spewing a small amount around the cap.

https://vorshlag.smugmug.com/Project...B61G9122-S.jpg https://vorshlag.smugmug.com/Project...B61G9124-S.jpg

We had this non-vented oil catch can lying around from another project, so that was re-purposed to catch the puke from the power steering pump that was getting past the (new) fluid reservoir cap. The next was an oil pan drain plug leak that has been weeping just a little fluid. I abhor fluid leaks, and the new copper gasket fixed that, mostly.

https://vorshlag.smugmug.com/Project...DSC_0209-S.jpg https://vorshlag.smugmug.com/Project...DSC_0210-S.jpg

As I was staring at these big, meaty tires one day, Ryan pointed out that the rear tires had slipped on the wheels. He had marked the location of the tire valves when he installed these 345mm A6s and they had slipped a good bit (the fronts had not). Must have been from that massive 354 ft-lbs of torque, LOL! Not uncommon on freshly powder coated wheels, so we will scuff up the inner lips once these tires are off, which should give enough bite to keep the tires from slipping.

By this point I was thinking of ways to get the car back into TTC, but how do we cover up that MESS that I made of the fenders?? We cut all 4 fender lips off to clear the big tires, and the car would look turrible with the 245s back on.

https://vorshlag.smugmug.com/Custome...IMG_2239-S.jpg https://vorshlag.smugmug.com/Racing-...DSC_9262-S.jpg

Around that time an old college buddy, Jason, brought his BSP autocross prepped 1989 Corvette by the shop, above. He took off the 17x12" autox wheels and mounted up some 18x10.5" Z06 street wheels at all 4 corners and got the dang thing registered and inspected. It being over 25 years old made for a simple $7 inspection of lights, wipers and horn. And the Vintage plates were like $70 for 5 years! But more importantly, I looked closely at his rear flares. These were just the GM "export" flares for the C4, also used on the 1996 Grand Sport to cover a slight poke from a 17x11/315mm factory rear tire they used. Hmm.

Jason and I had discussed the C4 many times over lunch in the following weeks, and I was bouncing ideas off of him about the "Big Tire" test, how badly it went and how expensive it would be to keep going down this path. He, like many others, told me what I didn't want to hear... you gotta give up the big tire and put the car back in the class it was built for: TTC. I had also acquired another chassis to build for a shop car that could actually bring us some actual business, so investing a lot more in the C4 was not wise.

345 vs 245 Hoosiers - just look at how much rubber I'm having to give up!

One argument made was that a fully prepped TTC Corvette would sell for more than a half-assed prepped TT2 C4. This was a difficult choice, but it made the most sense for the business. Painting the car and cage would help resale value, and that was something I needed to plan for.

Yeah, it was time to go back to TTC for Project #DangerZone.

https://vorshlag.smugmug.com/Project...DSC_0460-S.jpg https://vorshlag.smugmug.com/Project...DSC_0459-S.jpg

I decided to buy a pair of the Grand Sport flares, just to see if they covered up the sins we created when we cut the rear fenders to clear the 345mm tires. Sure enough, the rear fender cuts are almost 100% hidden under these... so we conceivably have an easy way "back to TTC", if needed.

https://vorshlag.smugmug.com/Project...DSC_0338-S.jpg https://vorshlag.smugmug.com/Project...DSC_0340-S.jpg

With the sticker set of 245s already mounted on the 2nd set of SSR 17x9.5" wheels it was a quick change to go from 335F/345R A6 tires to the 245 R7s. I re-ran the numbers, weights and power for the 2016 rules and realized that since the car had to weigh 3260 pounds for this year, now we could make up to 291 whp. And since the rebuilt 1992 LT1 made 288 whp (SAE corrected), I wouldn't have to run even more ballast to make up for the 4 extra whp it makes now (it made 284 whp before the rebuild). So for 2016 we would need to just run the 58 pounds of extra "minimum weight" ballast.

https://vorshlag.smugmug.com/Project...DSC_0339-S.jpg https://vorshlag.smugmug.com/Project...IMG_2338-S.jpg

One small last thing I decided to modify for TTC use now was to locate a second pair of the Bear Racing .875" thick spacers for the front, keep the rear spacers in place, and widen the track with the skinny tires. We can increase track width up to 4" over stock in TT-Letter classes without a penalty, and this spacer addition would add 1.75" of track at both ends. More mechanical grip is the payoff, and if you can keep the tires out of the side air stream it doesn't add any aero drag.


This is what we ended up with, above. It has some monster fender gaps but the car is actually sitting very low (maybe too low - we are addressing this soon). At this point I had pulled the "TT2" class designation decals off and Jon was cutting some "C" decals for all 4 corners. I signed up both cars for NASA @ MSR-Cresson - TTD in the BMW and TTC in the C4 - including one Instructor entry for me. Amy was supposed to run the BMW, but had a death in her extended family which required her to travel across country over the race weekend, so at the last minute I was looking for a way to get both cars to the event...


It rained the entire week before this event but it looked like it would clear up sometime Saturday. I mentioned to my crew here that I needed someone to fill in for Amy. Our Order Desk Manager Jon started talking a bit of smack, so I surprised him with an offer to drive the red BMW in HPDE, and he took it. We did some last minute prep on that car and he drove it out to Motorsport Ranch Cresson on Saturday morning. I left the shop at 7:20 pm on Friday night with the C4 in the trailer and slogged through the rain to get to the track. I was unhooking at 9 pm, in the pitch dark, parked in the grass, on a steep hill. There was NOWHERE to park, as even with the rain looming, over 200 people showed up to run HPDE, TT, and W2W.

https://vorshlag.smugmug.com/Racing-...IMG_2406-S.jpg https://vorshlag.smugmug.com/Racing-...IMG_2428-S.jpg

continued below

Fair! 03-25-2016 08:54 AM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

Saturday morning it was still wet and sprinkling, so I drove the BMW in the TT Warm Up on street tires, with Jon riding shotgun. I had hoped to show him "the line" (this was his first time driving at MSR-C), but anywhere on the 16+ year old, original track surface that was "the line" was polished smooth. Add in the water and it was like driving on ice, so the trick in the rain here is to NOT drive anywhere near the proper driving line. The marbles is where the grip is, strangely enough.

https://vorshlag.smugmug.com/Racing-...p-031116-S.jpg https://vorshlag.smugmug.com/Racing-...YD2H2446-S.jpg

Event Photo Gallery: https://vorshlag.smugmug.com/Racing-...-MSR-C-031216/

After that drift-fest TT warm-up we came in - and realized we forgot to install the AMB transponder on this car. No official time, doh! So that meant that I would be gridding in the next TT session at the back, no matter which car I brought to grid. I ran the red 330 again and got a time good enough for the win for the day, but I was itching to get into the once again TTC classed C4. This would be the first time it has been run in TTC with the fresh motor, on a sticker set of tires, with the upgraded spring rates, and the "rebuilt" OEM shocks. Aka: the most prepped it has ever been for any class.

https://vorshlag.smugmug.com/Racing-...P7B_9774-S.jpg https://vorshlag.smugmug.com/Racing-...IMG_2404-S.jpg

After lunch the rain finally let up and began to dry, so we unloaded the Corvette. The track surface dried off in TT session 3 and I took the C4 out for the first time on Saturday. We had 6 cars in TTC class so whoever won today could potentially take home 2 Hoosier tires. I was mired in traffic and couldn't get a clear lap, ran a 1:24.X in the session with 2-3 passes per lap, but I at least moved up the grid. The old MSR-C 1.7 CCW track record for TTC was a 1:25.1, and both BJ and I had both beaten that already.


In the final TT session of the day I was trailing BJ Meyer badly in his TTC prepped Mini Cooper S (parked to the left of me in the image above). Supercharged, on coilovers, lots of boost, and driven well at this, his home track. In the final TT session of Saturday I put down a blistering 1:22.206, with only one semi-clear lap for traffic, with a number of small driving mistakes. But BJ put in his personal best of a 1:21.996, taking the win for the day. My time was good enough for 2nd, but I knew I had more in the car - predictive showed some high 1:21's but traffic kept killing my best laps. At least I'd be further up the grid for Day 2!

https://vorshlag.smugmug.com/Racing-...P7B_0407-S.jpg https://vorshlag.smugmug.com/Racing-...P7A_2768-S.jpg

Jon was in HPDE3/4 and as the track dried up we swapped on the Hoosiers and he was having a blast. I saw the TT "needle go into the vein" for Jon this weekend... he's been cooking up TT builds on paper all week!

Sunday morning was a bit of a mess, and it was my fault. This was the Daylight Savings "leap forward" day, where we lose an hour at 3 am. My smart phone alarm can catch that, of course, but the problem was I set the alarm for... a weekday. So I overslept and made us super late to the track. We rushed to the track from the hotel but I made it in time to get into the 330, throw some fuel in it, and make it to grid with 1 minute to spare. I ran the first TT session in the BMW and again was mired in traffic. Getting a good lap in a gutless car that cannot pass anything is actually pretty difficult. I ran a 1:27.604 in the car Saturday but only managed a 1:27.854 on Sunday in this, the only session I ran the 330. Turned that car over to Jon for the rest of the day and spent the the other trying sessions to chase down that damned Mini in TTC!

https://vorshlag.smugmug.com/Racing-...IMG_2412-M.png https://vorshlag.smugmug.com/Racing-...P7A_5778-M.jpg

In TT session 2 the Corvette was at least gridded 11th out of 39, so there should be a better chance of getting a traffic free lap? Well, not so much. I was on a quick lap and lost track of which car I was in... there's three left handers (T5 - T6 - T7) in the back section of the 1.7 course that I can take with the throttle matted in the TTD BMW, but not in the C4. Well I mis-remembered that, and kept the gas pedal mashed, and put two wheels off at the exit of T7 (Tombstone). And the grass was still wet, so that two off quickly became 4, which turned into a big graceful loop across track and into the grass. Yea, I spun it, which DSQ'd the session. I came back in and tried to get my head on straight.

BJ was checking to see if I was going out in TT session 3, and I told him that I damn sure was. So I got to grid for that session and all 3 of the top TTC cars were lined up pretty closely. BJ's Mini was sitting on a 1:21.8, I was gridded right behind him, with Mark Schnoeer's TTC M3 just behind us both with a 1:24.8 (last year's record setter). I needed to get the lead out and put a clean lap in for the day in the C4. I knew the C4 had enough performance in it to beat the Mini - it had beaten it every time before - but there was the whole driver thing I had to do.

I didn't know how much more the master cylinder had in it, but I was going to push for the win in this session. The first two laps of this session were traffic, and I passed some of the faster cars gridded ahead of me, but BJ was always right there about 30 yards ahead, too. By the start of the fourth hot lap I had passed the cars ahead I needed to, built a gap to BJ's Mini so I wouldn't be running into his mirrors, and got the 245 R7s up to temp. The brakes felt OK so I went for and achieved my best lap of the weekend....

Sunday TT Session 3 in-car video

All weekend I'd been touching 106 mph entering Big Bend and on the next straight reaching 110 before braking into T9. With these short tires, 110 mph is at the top of the rev range for this LT1 engine, so I started using 5th gear right before the start finish, and it gained me 2-3 mph (noted 112-113 mph into T9 on those laps). If you listen carefully in lap 3 in the video above, as I'm exiting the fastest corner of the course (Big Bend) I am running out of revs in 4th gear, so once again I planned to use 5th. I looked and saw that Predictive Timing showed me 1:21.6 right as I go to grab 5th... and CRASH! Synchros balk not once, but TWICE! It finally went into gear as I'm cursing the Germans who built this gear box. Even missing 5th gear twice the AiM logged a 1:21.90 lap time.

Son of a... Hindsight being what it is, I should have left it in 4th, because the 5th gear synchro has been "hit or miss" since we bought this car. Its an EXPENSIVE rebuild on this ZF 6-speed, too. Would it have been enough to get ahead of BJ's 1:21.618 he ran in that session? Who knows. At least I knew I had dipped into the 1:21s, which was a goal all weekend.

To make matters worse, after lap 4 in that stint I lost the brakes almost completely, with a VERY long pedal braking into T9. No brakes and no way to fix it at the track, so I missed the 4th session. Oh well, that 1:21.9 would still feel good for 2nd.

https://vorshlag.smugmug.com/Racing-...IMG_2414-S.jpg https://vorshlag.smugmug.com/Racing-...P7A_5763-S.jpg

No, it just keeps getting better! The AMB timing loop borked that lap and showed it as a 1:03.786... Of course they had to throw out that bogus time (which was during my best lap of the weekend) and used my next quickest of 1:22.786 from that session (in traffic). Sure, its nearly a second slower than what I really ran, but I get it - timing equipment isn't infallible.


Even with a solid margin for Sunday, and after I told him I was done for the day, BJ still went out again in TT session 4 and dropped to a 1:21.589, resetting the TTC record with a strong number. So once again I was 2nd place in the C4 for the day.

https://vorshlag.smugmug.com/Racing-...IMG_2401-S.jpg https://vorshlag.smugmug.com/Racing-...IMG_2402-S.jpg

During the weekend I was instructing with 4 different HPDE1 students, and sometimes sprinting to the grid to meet them in time for their sessions after getting out of the two TT cars. The grid was way back on the 1.3 mile course, due to the lack of paved parking area on this wet event site. Instructing was fun but made for a hectic weekend and a lot of running around - I need to get a scooter or small track support vehicle, something to get around the paddock in.

https://vorshlag.smugmug.com/Racing-...P7B_0471-S.jpg https://vorshlag.smugmug.com/Racing-...P7A_5734-S.jpg

So once again the weekend was a mixed success. Driving two TT cars + instructing + talking to customers at our ever-busy trailer makes for a hectic weekend, but it was also a lot of fun. Jon got a check ride for TT and should have his comp license the next time he shows up to a NASA event. I managed two 1st place finishes in TTD (with only one timed TT session each day in this very under-prepped car) and two 2nd places in TTC. At least we were closer to the class winner in the C4 in this class, and we smashed the old TTC track record by nearly 3 seconds (but BJ reset it 3.5 seconds quicker than last year).

https://vorshlag.smugmug.com/Racing-...IMG_2416-S.jpg https://vorshlag.smugmug.com/Racing-...IMG_2418-S.jpg

We run the same 245/40/17 Hoosier R7 on both cars, so the C4's old tires become the BMW's new rubber, heh. After switching the tires on the BMW back to the streets we moved the trailer to pavement and loaded the Corvette for the trip home. If there was any brake pedal I'd have run the last session to try to chase BJ Meyer down. After instructing in the 5:20 pm HPDE session, I didn't get out of there until after 6 pm, and that 2 hour tow home made for a another 12 hour day. But compared to my normal 7 day a week work days, this was a breeze! ;)


After seeing results that were quicker on the 245 R7s vs the 345 A6 tires, it looks like we're heading back to TTC for the rest of this season. Jumping 3 classes up with just a tire change was foolish, and the proper path involves spending a lot more money than we have budgeted for this car.


At a smooth track like Cresson I ran a 1:23.7 in January at the SCCA Club Trials on the Big Tires (335F/345R), yet I ran nearly 2 seconds quicker (1:21.90) on the little tires with no other changes in March. Being the "fastest car of the day" in January gave me a false sense of confidence, and over-shadowed how the car felt in bumpy sections of this course. At MSR-H the car was tougher to drive on the Big Tire setup, just due to the rougher track surface. In TT2 there I was 3 seconds slower than my 2015 pace on the narrower TTC tires.

Please don't confuse this handful of "data points" with busted theories that "narrower tires work better" on a road course for any given car. I made some posts on Facebook (#SmallTiresMatter) that were in jest, but several people took them seriously. We've proven the small tire theories wrong, time and time and time again. A lot of folks have a lot of theories on why we were quicker on the narrower tires, but trust me... its just a simple matter of the current shocks not working well with the MUCH higher grip levels the wider tires made.

https://vorshlag.smugmug.com/TechArt...DSC_9935-S.jpg https://vorshlag.smugmug.com/TechArt...B61G1632-S.jpg

With the right shock and spring package it would be quicker on the Big Tires. Always. We made big drops in lap times on our TT3 Mustang on each jump up in tire size, going to the same tracks. We went from 265 to 305 tires, 305 to 315, and 315 to 335/345, and each increase in width was a drop of 2-3 seconds per lap. Big Tires Do More Work. You just have to upgrade the rest of the suspension to deal with the higher mechanical grip levels. 25 year old OEM dampers ain't the hot ticket on 345 HoHos!

If we had the points for TTC, I'd still install some adjustable MCS dampers for this car. There are still handling issues on even the smaller tire with the factory shocks, just not as pronounced. We're just "point maxed" for TTC right now and cannot add any more mods. Raising the ride height will reduce the chances of hitting the bump stops on bumpy courses, which it still does on the 245s, so that is planned before the TWS event. Here's our TTC build point budget:

Base classing: TTC*, 3260 pounds
- 7 penalty points for the base class "star"
- 10 points for the Hoosier R7 compound
+ 1 bonus point for running 10mm smaller than TTC base tire of 255mm
- 1 point for cold air mods / vented hood
- 3 points for spring rate change
= 19 points allowed within the first class (1 more point moves it to TTB)

Shocks would be 3 more points we don't have. The inherent TTC class competitiveness on the smaller tire, and budget constraints, just doesn't make sense for us to upgrade the suspension and other parts to make the big tires work on THIS car.

For TTC use this season we do have some small changes planned to make the car easier to drive and maybe a tick more competitive. A change to a smaller diameter racing steering wheel and a quick release will make it easier to see gauges + easier to get into the cabin of this car (after removing the steering wheel and hanging it out of the way).

https://vorshlag.smugmug.com/Vorshla..._DSC2047-S.jpg https://vorshlag.smugmug.com/Vorshla..._DSC2601-S.jpg

A full Tilton brake and clutch pedal assembly and firewall mounted Master Cylinders will be going in soon. Those will replace the factory pedals and OEM master cylinder (for zero class points), so we can hopefully get past these crappy reman MC units failing so often. Removal of the OEM plastic brake booster is another failure point we can lose, also.

Next few NASA Texas events:
  • April 22-24 – Texas World Speedway
  • May 21-22 NOLA Motorsports Park – Crossover with NOLA
  • June 11-12 – Hallett Motor Racing Circuit
After that we will add the small over-flares to fix the cut off fender lips, then maybe... hopefully this summer, get some new paint on the body and cage/interior. Check back next time to see what we do next to #Dangerzone to hopefully make it less dangerous! ;)


Fair! 11-09-2016 05:30 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project Update for November 9th, 2016: On this, the day after an historic election, I think we need a distraction. Let's talk about race cars - welcome to the #DangerZone!


A lot has happened to our C4 Corvette since my last post. We developed a custom dual Tilton master cylinder brake setup to replace the constantly failing stock masters and booster. Then we tested that at an HPDE event and it worked flawlessly. Then we prepped the car for paint and off it went to my buddy Shiloh's shop. Afterwards the car came back SO beautiful we felt obligated to spruce up a few other things. Long story short - its now too pretty for me to own and race anymore, so the car is For Sale. Read below to catch up!


After four rebuilt OEM brake master cylinders failed on this car we were out of patience with the stock parts. These were not lasting a weekend and the failure mode was pretty abrupt: one lap you solid had brakes, then on some random corner the pedal would go to the floor and you had nothing. Bleeding wouldn't help a bit. Luckily none of these failures led to a crash - so far.

https://photos.smugmug.com/Projects/...DSC_9839-S.jpg https://photos.smugmug.com/Projects/...DSC_0597-S.jpg

Jason had been wanting to make a brake solution to fix a situation just like this for years. This would replace the stock bake master cylinder and brake booster. As I have mentioned in the past the stock booster is PLASTIC on the C4 and they fail regularly as well (this car already had one rebuilt unit installed).

https://vorshlag.smugmug.com/Vorshla..._DSC2047-S.jpg https://vorshlag.smugmug.com/Vorshla..._DSC2601-S.jpg

Real race cars tend to not use vacuum assist brakes or OEM stepped bore master cylinders. For safety and tune-ability they use two separate master cylinders, which can vary in bore size, and tend to use them with new pedal(s), either hung from above or from below.

https://photos.smugmug.com/Projects/...DSC_2928-S.jpg https://photos.smugmug.com/Projects/...B61G0406-S.jpg

Racing dual aftermarket master cylinder setups are almost always setup with one master cylinder for the front and one for the rear, plumbed independently for safety. A "balance bar" can then be employed to adjust the brake balance from front to rear quickly - literally by pressing on one master cylinder more than the other, via a lever at the brake actuator rod.


Race cars with manual transmissions (which is most) will often also replace the clutch pedal and master cylinder at the same time, so there are 2 pedal/3 master mounting kits you can buy. And if the brake and clutch master cylinders are hard to access (on the floor or under the dash) for fluid checks/refills, the fluid reservoirs are often remote mounted elsewhere, like above.

The trick in mounting these into an OEM chassis is having something to mount them to - usually top hung pedals are mounted to a roll cage tube, and bottom hung are mounted off the floor. Those both take lots of time to mount and brace. Sometimes you can mount the brake masters and new pedals right to the firewall, but usually they still need some support from a roll cage. We have done dual masters all 3 ways.


There are complete "pedal box" kits you can order, sometimes even for a specific car. Most race cars with gutted interiors and roll cages are built using generic pedal kits, like the Tilton above. Mounting top mounted or "hung" pedals from a roll cage tube is a good bit of work, and there is still a lot of factory wiring behind the dash panel on this car (it has all of the working gauges). Floor mounted pedal boxes are slightly more common.

These are the parts we sourced - the Tilton MCs, Tilton balance bar, Tilton remote knob, and the pedal multiplier

The main issue we had was that the factory floor on the C4 is too narrow and is somewhat weak (fiberglass) and the firewall isn't really open to adding in more mounting holes (fiberglass), but the OEM brake booster opening is fairly strong - see below at left.

https://photos.smugmug.com/Projects/...DSC_0607-S.jpg https://photos.smugmug.com/Projects/...DSC_0693-S.jpg

We also didn't want to replace the stock pedals because, well, that's a bunch of work that is very difficult to un-do. We wanted to test a theory so a bolt-on solution that uses factory mounting holes was preferred - if this didn't work we could just put another new brake master and booster back on.


The solution (above) we came up with is a setup that has a CNC billet aluminum bracket / mount that bolts to the OEM booster mounting holes at the firewall. This way we could keep the OEM brake pedal arm and bracket. No cutting, no fabrication to the car at all, purely a bolt-on assembly. This firewall bracket has a pedal multiplier setup built inside that changes the pedal effort for the now manual brakes. This make the brakes have more of an OEM-like amount of brake pedal travel. We might never make another one for a C4, but this would be a good test for an idea for other, more relevant cars that might need this solution.


Forward of this billet firewall bracket are four studs that hold a steel bracket, to which the two Tilton master cylinders are mounted. In between the pedal multiplier and the masters goes the actuator rod and balance bar. This leads to a dial on the dash to adjust front to rear bias on the fly.


It took some tricky machining on our CNC mill to make the main billet aluminum part, but we wanted some new challenges for our machines. Jason made this piece in 3 CNC setups and mounted the pedal multiplier to the main pivot.

https://photos.smugmug.com/Projects/...DSC_0684-S.jpg https://photos.smugmug.com/Projects/...DSC_0692-S.jpg

Ryan built the steel bracket that the two Tilton master cylinders mount to from a CAD drawing. Then all of this was bolted together into this assembly shown below. He then made a custom actuator rod that connected to the factory brake pedal under the dash. The rest of the pedal assembly was left stock. This was done to make this a bolt-in upgrade.


Once installed on the car we had to find a place to mount the 1995 Corvette ECM, which normally goes on a bracket near the brake booster. The solution is shown above, which unfortunately hides some of the sexy machined bits in this new, dual MC manual brake setup.


We did not want to chuck out the ABS system so we plumbed the return lines from the ABS pump into a Y-fitting that fed back to both master cylinders. This allowed us to keep the ABS functional.


The Tilton balance bar adjustment knob was mounted to an aluminum panel on the dash that also holds the Traction Control switch (it defaults to off now). We initially tested this new setup on the street, and quickly changed master cylinder bore diameters to get more braking force. Even using the best hydraulic ratio formulas you often have some trial and error - we were close, but needed one more iteration. The pedal effort is firmer than before (no vacuum assist) but the pedal travel is perfect and heel-toe is still easy. We then needed to test the car on track to prove it...


During this brake master upgrade period we also made some other small changes to the Corvette, to make it more reliable on track as well as to clear up any TTC class legality questions.

https://photos.smugmug.com/Projects/...ling-004-S.jpg https://photos.smugmug.com/Projects/...ling-005-S.jpg

Earlier in the year, as we were fighting brake master cylinder issues that we couldn't diagnose easily, we threw some hastily made brake duct inlets and backing plates on the front of the car. That was when we briefly ran the car in TT2 class, which has no aero restrictions. The easy place to add the brake cooling air inlets was under the front nose. Because this is not exactly a good high pressure spot I decided on some vertical panels (see above) on the outside of these 3" round vents, to keep air from spilling away laterally from the inlets.

https://photos.smugmug.com/Projects/...DSC_0609-S.jpg https://photos.smugmug.com/Projects/...DSC_0600-S.jpg

After some discussion with two different NASA race directors it was felt this vertical plane we added was in "a grey area" that could be protested, and someone could argue this deflector as a "canard" or "air dam". No, these didn't provide any downforce, and actually probably added a little lift, but they look like canards and the NASA rule book doesn't define terms like "canard"... its all up to the rules maker or protest judge to interpret the rules however they see fit. So to remove any doubt, we redesigned these brake duct inlets and removed the potential brake cooling "canards".

https://photos.smugmug.com/Projects/...DSC_0608-S.jpg https://photos.smugmug.com/Projects/...DSC_0697-S.jpg

These plastic NACA ducts had an identical 3" hose connection and they were, in fact, much easier to install than the work needed to fabricate the "canards" and and brake duct inlets we had used before. Are they as effective? Hard to say without some very detailed testing, but these were deemed TTC legal without any doubt (or points) by the same race directors, so they went on.


A fire proof Nomex shift boot and aluminum mounting base were then added. We use this Joe's Racing shift boot kit on many builds, dating all the way back to our Alpha E36 LS1 car back in 2006. This boot goes over the old rubber transmission tunnel boot that was now 25 years old. This Nomex boot added a layer of noise, exhaust, and fire sealing to the stock transmission tunnel.

https://photos.smugmug.com/Projects/...DSC_0601-S.jpg https://photos.smugmug.com/Projects/...DSC_0708-S.jpg

continued below

Fair! 11-09-2016 05:31 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

I had noticed a bit of heat on my right leg in long stints so Brad added the thermal / reflective DEI material to the trans tunnel (see below), which is adhesive on one side. This has a layer of fiberglass insulation underneath the infrared reflective layer on top. We use this DEI insulating material on all sorts of cars to shield passenger areas or things like fuel lines from exhaust heat.


Around the same time as these things were going in I ordered another pair of the ZR1 / GM export flares for the C4 chassis as well as an ALDL connector (looks like OBD-II connector).

https://photos.smugmug.com/Projects/...DSC_0560-S.jpg https://photos.smugmug.com/Projects/...DSC_0661-S.jpg

After a couple of tries at ordering via part numbers we finally received the correct ALDL connector for the 1994-1995 "Pre-OBD-II" connector port.

https://photos.smugmug.com/Projects/...DSC_0660-S.jpg https://photos.smugmug.com/Projects/...DSC_0671-S.jpg

That was wired in to the ECM at the computer, then the connector mounted to the side of the dash on the passenger side. This port will help with tuning in the future, as well as checking CEL codes.

SCCA Club Trial & PDX, MSR-C, May 8, 2016

The next event we could sign up for that allowed us to test the brakes was this SCCA Club Trial and PDX event at MSR-Cresson. The weather was pretty poor and it rained off and on that day. Somehow we got almost no pictures of the two cars we brought, and the video camera I brought had a dead battery, so I got no video. I did get some dry laps in several sessions and the brakes were rock solid.


This was a combined PDX (HPDE) and Club Trial (Time Trial) but they didn't post any results. I asked for my times recently and they gave them to me - best of 1:24.3 in traffic. Out of 26 in Club Trials the Corvette posted the 3rd fastest, out paced by a Wolf (prototype) and TT3 M3. I ran a bunch of 1:24 and 1:25 lap times that day. The SCCA Club Trials events here aren't quite like what NASA runs, and the field has "a full range of talent". So traffic with 26 cars on 1.7 miles was as bad as you could expect. It was cold, rainy, cruddy weather. Still, I ran the car in 4 sessions and the brakes felt perfect.


I instructed that day and rode through with 3 different people, including Brad from Vorshlag in 2 sessions, an S550 Mustang racer for 2 sessions, and Amy for a session. Made good progress with my two PDX students and Amy dropped 4 seconds per lap in the 330 after some coaching. She was on the 245mm Dunlop street tires so the lap times she ran we're relevant to our times on Hoosiers.

I had that "Brake... Brake... BRAKE!" moment riding with Brad on one lap, hehe!

I didn't want to abuse the fresh Hoosier R7s so after fighting traffic most of the day I skipped 2 sessions and put the Corvette back in the trailer after confirming that the pedal effort was good, the balance worked, and the brakes were reliable.


I had planned on racing the car in the next few NASA race weekends but that just didn't ever happen. After the car was painted it was just too damn pretty...


After this May test event the car sat for a week then I decided to skip the NASA @ Hallett event in June and get a jump start on the paint work I felt the car needed to be able to sell.

https://photos.smugmug.com/Projects/...IMG_3123-S.jpg https://photos.smugmug.com/Projects/...DSC_1841-S.jpg

The first step was to remove all of the decals from the car. Brad, Jon and I took turns and used low setting on the heat gun to soften the adhesive and pulled each one off without issue. Well, except the driver's door, which was entirely wrapped. It had some paint damage when we bought the car so Jon had wrapped that entire door in white film. More paint pulled off as this sheet was removed - Not a worry as this entire door would get reworked professionally at Heritage.

https://photos.smugmug.com/Projects/...DSC_1848-S.jpg https://photos.smugmug.com/Projects/...DSC_1847-S.jpg

We pulled all of the rear plexiglass hatch off first, then the roof skin. This roof panel was black but I wanted to see it in white, so that would be prepped for paint work by Heritage.


Our local glass guys at Titan came by to remove the front windshield, which waited in my office for 2 months during the paint work.

https://photos.smugmug.com/Projects/...DSC_1843-S.jpg https://photos.smugmug.com/Projects/...DSC_1846-S.jpg

Then the side view mirrors came off, padding from the cage was removed, seat and ballast box were unbolted, and all the nets came out. We cleaned the car and loaded it into the trailer for the trip to Heritage in Sherman, Texas.


Because this was a super busy time for them - 2 hail storms this Spring have had the body shops for 100 miles loaded up all year - I told them this was no rush. This way they could take their time and fit this admittedly lower paying paint job in between more lucrative insurance hail work.

https://photos.smugmug.com/Projects/...IMG_3228-S.jpg https://photos.smugmug.com/Projects/...IMG_3302-S.jpg

The front bumper cover was never pretty but they managed to rework the nose nicely. This portion of body work made a huge difference in the end and I'm glad they spent the hours there.

https://photos.smugmug.com/Projects/...IMG_3232-S.jpg https://photos.smugmug.com/Projects/...IMG_3305-S.jpg

The driver's door was a donor from another C4, installed many years ago, and it had existing damage and didn't match the rest of the car. They still managed to rework the fiberglass skin and get it looking smooth as glass before paint.

https://photos.smugmug.com/Projects/...IMG_3229-S.jpg https://photos.smugmug.com/Projects/...IMG_3303-S.jpg

The rear bumper cover also needed some love, but they got it sanded down, smoothed out, primed and ready for paint.

https://photos.smugmug.com/Projects/...IMG_3306-S.jpg https://photos.smugmug.com/Projects/...IMG_3301-S.jpg

The roof panel was sanded and smoothed, then primed before paint. Many hours were spent smoothing the hood and other fender panels, and of course the ZR1 export flares were bonded to the fiberglass, reshaped, smoothed, and integrated before being primed.

https://photos.smugmug.com/Projects/...IMG_3430-S.jpg https://photos.smugmug.com/Projects/...IMG_3429-S.jpg

The roll cage took many hours to sand, wash, tack and prime, then paint. The interior and cage were painted separately from the body, but both received several base / clear coats of Siemens paint in GM Arctic White - which has no pigment, just white base. It is the brightest white made and it really POPS when you shoot it with a high gloss clear.

https://photos.smugmug.com/Projects/...IMG_3418-S.jpg https://photos.smugmug.com/Projects/...IMG_3414-S.jpg

I picked the car up in mid August 2016 and was blown away. It looked... way nicer than I had hoped for. The price was less than it should have been, but still a good chunk of cash. I had the car painted to help increase the resale value and I think we got more than we bargained for...


Pictures simply do not to this paint job justice, and the pictures look GOOD. On a sunny day the brightness of this car is dangerous... #DANGERZONE


After getting a few shots of the freshly painted interior and exterior outside, we brought the Corvette in for the final list of updates.

https://photos.smugmug.com/Projects/...DSC_3078-S.jpg https://photos.smugmug.com/Projects/...B61G9462-S.jpg

I had a few things listed that I felt were necessary to "complete" my vision of this project.

https://photos.smugmug.com/Projects/...DSC_3088-S.jpg https://photos.smugmug.com/Projects/...DSC_3094-S.jpg

That open "storage cubby" area behind the seats always bugged me, so I asked Donnie to make an aluminum panel to cover this and match the flat rear deck floor height. With some fiberglass-specific nutserts added the panel can be unbolted quickly for access to the ABS hydraulics behind the driver's seat. There's room for the battery on the other side but we decided against relocating that for now.

continued below

Fair! 11-09-2016 05:31 PM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
continued from above

https://photos.smugmug.com/Projects/...DSC_3142-S.jpg https://photos.smugmug.com/Projects/...DSC_3195-S.jpg

The passenger floor always bugged me with its bumpy OEM shapes so I asked Donnie to make a pattern and then make a 2-piece false floor for this side. The front section can unbolt and the rear section sits under the weight box. Looked good.


Ryan made the reinforced false floor for the driver's side, which you step on to get in and out of the cage on that side. We will add grip tape for the buyer when they arrive to pick it up - just showing off the shiny aluminum for now.

https://photos.smugmug.com/Projects/...DSC_0520-S.jpg https://photos.smugmug.com/Projects/...DSC_3401-S.jpg

The gaping hole in the passenger side of the dash was where the factory airbag was located, which was removed long ago. The open expanse looked awful and I wanted an aluminum dash cover to be built on that side. The marked up picture (above left) was all Ryan had to go on.

https://photos.smugmug.com/Projects/...DSC_3402-S.jpg https://photos.smugmug.com/Projects/...DSC_3410-S.jpg

As usual Ryan thought farther than I had on the design and made it a 2-piece assembly. The upper portion mounted to the dash bar with rivets along two seams - bolts on the leading edge would be inaccessible with the windshield reinstalled. The lower section was removable with bolted hardware and nutserts installed into the upper section and along the sides.

https://photos.smugmug.com/Projects/...DSC_3463-S.jpg https://photos.smugmug.com/Projects/...DSC_3664-S.jpg

Of course you don't want shiny aluminum up by your eye line for glare reasons, so these two panels were removed and painted with many coats of texture black paint. Many coats. The picture above right shows this in place before the windshield was reinstalled, but the vinyl portion of the dash had some conditioner sprayed on to soak into the stock material, which was later buffed off to a dull haze.

https://photos.smugmug.com/Projects/...DSC_3620-S.jpg https://photos.smugmug.com/Projects/...DSC_3627-S.jpg

As well as the masking was done during the paint job, there was a hint of overspray in some areas and a couple of spots at the cowl we told them to leave in the stock black. These areas needed some prep and touch-up, so Brad masked off the freshly painted bits and prepped the areas that got some semi-gloss black paint.


Even the underside of the hood was cleaned and detailed, with the OEM colors and plastics shining like the day it rolled out of the factory. The difference here was amazing, but ate up 8+ hours of cleaning, prepping, painting, unmasking, and more cleaning.


After detailing the underhood area, the Corvette looks better than new, without a hint of over-spray and just enough gloss on the plastics to make my inner neat freak happy. This damn thing is too pretty for me to race now.

https://photos.smugmug.com/Projects/...DSC_4424-S.jpg https://photos.smugmug.com/Projects/...DSC_4440-S.jpg

One of the things I debated for weeks on was over reinstalling the quick release fire bottle or adding a full fire system. It was deemed more costly and not what some people want, so I will leave a fire system up to the next owner. This is all the car needs to go Wheel to Wheel racing, by the way. Well that and updated belts (they are FIA Cobra/Schroth 6-point belts, but expired). The original reinforcing plates were shined up and installed, then the Drake quick release bracket and HalGuard 2.5 pound fire bottle were put back in place on the tunnel.

The stock steering wheel with the airbag removed was always a HUGE eyesore, and it made for a cumbersome ingress/egress with the cage installed. The diameter was so large that it blocked my sight line to some of the factory gauges.

https://photos.smugmug.com/Projects/...DSC_0524-S.jpg https://photos.smugmug.com/Projects/...DSC_3925-S.jpg

I ordered the MOMO Model 88 in 350 mm diameter, and initially got it with the wrong 6-bolt hub adapter (p/n 2702, for GM telescoping column). We figured this out quickly and reordered the MOMO 6-bolt steering wheel hub adapter, part number 2401. This is the correct number for a C4 Chevrolet Corvette with standard GM tilt column, which we kept intact as it makes for easier adjustment for different drivers.


The new wheel really made a big difference, right? We had originally looked at adding a quick release steering wheel adapter but with the smaller diameter wheel and the tilt column its actually pretty easy to get into and out of the car with the steering wheel attached. I will leave a quick release up to the next owner, as these come in a variety of styles, thicknesses, quality levels, and prices.

https://photos.smugmug.com/Projects/...B61G0781-S.jpg https://photos.smugmug.com/Projects/...B61G0883-S.jpg

Of course the rear hatch, the seat, the belts, nets, and SFI padding were all reinstalled. Some sections of wiring harness were secured and tucked better. All sorts of little odds and ends were made perfect before the final "for sale" pictures were taken. This was both fulfilling and painful. On one hand I loved to see the C4 finished like I had always envisioned. On the other I knew I'd never get to race the car again - it was just too perfect now.


For now this works, and the interior looks really finished, and it better shows the work we do. Unfortunately it is with a car that most folks don't associate with Vorshlag, and that's where the problem lies...



After all of this work over the past 2 years - getting the car fast, reliable, safe and looking good - it is time to sell it. Why? Like I said, this C4 Corvette isn't really a car that we see all that often at our shop. Maybe its the labor rates we charge, or the lack of competitive C4 race car entries right now, but this car isn't really representative of the customer work we see. And I need to be racing in the types of cars our customers own and bring to us. Like how a new BMW dealership wouldn't field a 25 year old Honda race car, you know?


Would I prefer to keep this car and race it? YES! Its one of the nicest cars I have ever owned, now that it is finished and painted. Damn the "marketing", I'd love to run this car in 2017 in TTC class or even TT4 with a few changes. But being a small business owner there are always expenses I have to plan for, and this car needs to fund some purchases that I have to do to keep Vorshlag moving forward.


It really sucks how these things happen... our E36 LS1 Alpha car was really fast right before we sold it, but it had to fund many things in our business in 2009 when it was sold. Likewise in 2015 when we sold our TT3 Mustang. I damn sure wanted to keep it, but that sale paid for a big chunk of one of our new CNC machines, which the business really needed. This C4 has a lot of time and money tied up into it and with as clean and perfect as it is now, it would be crazy for me to run it another season.


This car is ready for a racer to jump in and go to the track today. Be it Time Trial or even Wheel to Wheel (with 2 small updates), it is ready to go and do so reliably. I put this For Sale Page up this week and I hope you go there and look at all of the pictures we have there. The price might seem high to some but I couldn't build another one like it for twice the asking price. That's just the reality of a fully prepped race car built by professionals - quality costs money. Any help you readers can do to spread the word is appreciated. I am sharing this same link on Facebook as well.


It is going to be tough to say goodbye to Project #Dangerzone, but hopefully someone will appreciate all the work we have done and buy this C4 soon.


Once it is sold I will update this build thread and hopefully share what we have planned with those funds - its a big step for our business, if I can make it happen. Until then this Corvette will wait in our shop until it finds its new owner.


Fair! 04-27-2017 11:01 AM

Re: Vorshlag Budget TT Build: Project DANGER ZONE
Project update for April 27, 2017: Not much to share for the past few months. We've tidied up a few loose ends and put the car for sale on an eBay auction. Let's catch up.


After my last post I had the crew finish up a few things that weren't 100% perfect. One of the false floors was re-done in aluminum and it now looks great.

https://photos.smugmug.com/Projects/...%2889%29-S.jpg https://photos.smugmug.com/Projects/...DSC_5063-S.jpg

One of my guys re-fixed the oil pan gasket and its finally perfect. Brad did a final clean-up on the Corvette and then I towed the car to my home shop, where it has been resting...

https://photos.smugmug.com/Projects/...IMG_5660-S.jpg https://photos.smugmug.com/Projects/...IMG_5657-S.jpg

There it has stayed while I got busy doing other things. We also found a lot of spare parts for the car when we moved it out of Vorshlag: new brake lines, belts, hoses, weatherstripping, a poly suspension bushing kit, and spare rotors, calipers, and another matching set of 17x9.5" SSR wheels. It all goes with the car!

https://photos.smugmug.com/Projects/...DSC_6198-S.jpg https://photos.smugmug.com/Projects/...DSC_6200-S.jpg

Last year I had put up a classified ad on the Vorshlag website, then we moved our website and all of the old links went away. I finally re-did that last week and made a Cars for Sale page as well - which has several Vorshlag cars (some completed and some "donor chassis") as well as a few customer cars we built.


I wasn't in a huge hurry to sell the car as I was still unsure about our other shop race car's future - this 2001 BMW 330Ci. It was struggling to win in 2016 and I had some doubts as to its ability in TTD class for 2017...


Well we finally spent the time needed to add power to this BMW and in 2017 it has been breaking TTD track records each time it goes out. Still 2+ seconds off the TTC Corvette's times, but that's to be expected. So since we had a a new "record breaker" we just recently decided to step up the selling game on the C4.


Yep, today is a big day on project #Dangerzone - I just launched the 7 day eBay auction. Low reserve, lots of bids in the first few hours. We'll see how this goes.

Also have my house for sale (need more land to build a bigger shop on) - which is another thing that has been keeping me busy for the last couple of months, long with launching a 2nd business and running Vorshlag.


Long story short - if you have anyone you know that might want this beautiful race car, please send them the auction link! Its legal for Vintage racing this year, too. I will update this thread after the auction ends.


All times are GMT -5. The time now is 11:06 AM.

Powered by vBulletin® Version 3.7.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.