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Unread 12-29-2014, 04:40 PM
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Fair! Fair! is offline
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Join Date: Jul 2004
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Default 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).

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.

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).

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.

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.

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.

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

Last edited by Fair!; 12-29-2014 at 06:07 PM.
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