Unread 09-20-2013, 02:23 PM
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Default Vorshlag BMW E36 LS1 "ST2 Build"

Note - this forum build thread is posted to concurrently on 4 forums, including here at Vorshlag.
Project Kick-off, September 17, 2013: Been a while since I kicked off a new BMW build project thread, as we don't show many of the turn-key builds we do here at Vorshlag. But this one is different and should be fun to watch as it goes together. We bought a 1992 BMW 325is coupe a while back and it is finally at Vorshlag about to get the LS1 engine swap and some other race prep it needs. We're building this car around NASA's ST2/TT2 classes, and it will be caged, flared, and LS1 V8 powered.

The purpose of this build thread is to show a behind the scenes look at how we do a turn-key E36 LS1 race car. We intend to eventually sell this car, as happens with everyone's car build eventually, so it will also document the build for the future owner. As with all of our 2013+ forum build threads, you can click on almost any picture for a higher resolution image. With a photographer like Brandon on staff we have show off the goods.

We had an E36 M3 front end on this car, but the seller reneged and now it has no bumper cover at all

We bought this particular E36 example a while back from a Texas seller, and it was running and driving - but just barely. The previous owner had bought it with a blown head gasket, then did some somewhat shoddy repairs to get it running again. At least he was honest about it (and I knew what to look for). After a new head gasket and liberal use of JB weld to fill cracks in the cylinder head, he got it to technically "run" but after just a few days of driving it was puking fluid once again and the motor was done. You see, once a BMW straight 6 engine overheats once, it is NEVER right again. The overheating often warps the head, or the head itself develops cracks, or both - this is because it has such a loooooong engine layout. Without major machine work to the block, head and internals, and a significant cash infusion, the original motor is pretty much as good as a lump of coal.

Luckily we have a great fix for that: an all aluminum 400 hp LS1 V8!

Long Running Debate: Street Car or Race Car?

E36 LS1 swap cars can work very well as beastly daily driven street cars, or you can add big tires and a cage and make them into great race cars. We've done both kinds of builds and this car was a candidate that could have gone either way. We had started it as a street car build, but switched to a race car shortly after coming back from the 2013 NASA National Championships.

Left: This LS1 powered 4 door E36 M3 has air conditioning and is a beautiful daily driver: Right: This LS1 coupe became a race car

Personally, I went back and forth with the direction of this build, since it was going to be a car built "on spec" that would likely be sold in 2014. Each type of build had its merits, and each would be attractive to totally different types of buyers. We had started on the street car option and had Allsheer Interiors recover the stock door and rear interior panels in new BMW sourced. 2-toned leather, and their work was flawless. The interior work was so good I almost stuck with the street car build, but the rest of the car just needed too much work to be in perfect condition: the carpet had a "heel" hole in it, the headliner was sagging, and most of the weather stripping needed replacement. And the car sat outside at my house for a few months (as our both shop and my home shop were full of customer cars rotating into and out of our main shop); it sat under a tree and the sap and crud really did a number on the weather seals and OEM paint, which wasn't great to begin with. But it had a straight body with zero rust or damage. So...

I knew pretty early on that we were going to have to repaint the whole car. Heritage Collision is going to do the paint work (they painted our E46 330, McCall's Z3 LS1, and the front end on our TT3 Mustang). And since they are going to be in there, and we already have a white 4 door M3 street car being built for another customer, we decided to go Full Retar.... I mean Full Race Car on this one.

The goal is to have this car stripped, caged and flared. Then take it to Heritage and have them paint the interior, under the hood, and exterior back in a bright white (probably not the OEM off white that is Alpine White 3). The exterior will be 2-stage but the interior, cage and underhood will be single stage. We have another E36 candidate I picked up that will donate a lot of parts to this 325is... a hail damaged, engine-less silver 4 door E36 M3. This one was also picked up locally and we will use this chassis' front and rear sub-frames, M3 brakes, M3 diff and halfshafts, and M3 bodywork for the ST2 build.

The '92 325is came in our shop today and was pressure washed, where many months of tree doodoo was removed. Body is very clean, just lost a lot of luster and some more clear coat thanks to mother nature. The crew in our shop also began building adapter beams for our roll around "body dolly" so that we can get this E36 chassis mounted to our custom built dooly, then remove the front and rear subframes and still be able to roll the car around. Once it is on the dolly we can begin by pressure washing and painting the underside (white epoxy paint), then the chassis reinforcement and cage work will start. To avoid any problems with ST rules it will only get the same reinforcement plates that come on the OEM '96-99 M3. We will TIG weld the Turner rear subframe and rear swaybar reinforcement kits as well as a front K-member "motor mount reinforcement kit". Then we will remove, cleanup and swap over the M3 K-members and rear axle parts to this ST2 chassis and the 325is subframe bits will go onto the badly dinged up M3 to make it into roller. Then the M3 roller will be sold off (100% rust-free Texas chassis with a clear Texas title, anyone?). Could be a good buy for someone with a Rust Belt M3 that was getting a bit crusty - after they switched over their drivetrain, diff, seats, hood and trunk, it would only need some roof work and it could be a rust-free running M3 again. Who knows.

Wait... What Class is That?

Some of you may not have heard of ST2 or even TT2. These are two different classes that share the same ruleset within NASA's racing hierarchy.
As you can see if you read the actual rulsets, TT2 and ST2 are essentially identical, with the difference being that ST2 is made for W2W racing and TT2 is a time trial class, without the same safety requirements. A lot of cars are built to run both, which you can do in the same weekend if you "Supersize" your entry. Gives you 2x the track time and twice as many chances at contingencies for not much more cost. Great deal for NASA racers.

The intent of this E36 LS1 build is to make a legal ST2 "Wheel 2 Wheel" race car that we can race briefly (likely in TT2, so we don't get a scratch on it), all with the intent to sell. Big "FOR SALE" decals will go on from day 1. It will be built around 18x11" Forgestar wheels front and rear and 315mm Hoosier tires, of course it will have a complete aero package, a full 1.75 x .095" DOM cage built to the NASA CCR, a pair of COBRA FIA legal seats, and a proper fire system. We will take it to a NASA event tor two, get it log booked, put in some lap times, then try to see if we can find a new owner for it.

This build will take the best parts and know-how we've used in our turn-key LS1 E36 installs, using the best LS1 swap parts on the market (duh - ours!), plus a lot of the knowledge we have gained from other race car E36 LS1 builds (like the original E36 LS1 "Alpha" car, among others) and racing in NASA since 2008. This build will allow us to turn this non-running 325is automatic E36 chassis, that was about to be discarded after it blew a head gasket, and transform it into a simple yet brutally fast race car that can be raced (hopefully) competitively in ST2 or TT2 class, against cars costing a lot more.

This class is based around an 8:1 weight to power ratio, which should be fairly easy to reach with this car. The goal is to get the chassis down to under 2600 pounds soaking wet and then use a mild (sub-400 whp) HKE-built aluminum 5.7L LS1 V8 and a T56 6-spd for the drivetrain. We want a reliable package with low cost consumables, big grip from the 11" wide wheels and tires, and some extra stick from added downforce. BMW handling + LS1 power = the best of both worlds.

Should be a fun little race car when we are done with it. We will post more here when we have progress to show.

More soon,

Last edited by Fair!; 11-23-2013 at 02:55 PM.
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Unread 11-21-2013, 05:52 PM
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Default Re: Vorshlag BMW E36 LS1 "ST2 Build"

Project Update for November 21, 2013: We got really busy in the shop back in September but finally got some time freed up to work on the ST2 project a little in October and a bit more time in mid November. Let's cover the progress to date...

Olofagus washing the hail beaten M3 "donor car" behind our shop. Those hideous headlights are for sale!

Donor Chassis Stripped and Sold

We had picked up this silver 1997 M3 4 door "donor car" shown above a few months back, which was a rolling chassis that had severe hail damage. I bought this one just to get the good M3 bits like the front spindles/brakes and rear subframe/trailing arms/hubs/uprights/LSD diff/halfshafts/brakes. We always upgrade the non-M E36 cars getting an LS1 V8 to the M3 limited slip diff, stronger halfshafts, and stronger/bigger brakes, uprights, etc. This subframe is held in place with 4 bolts and is easy to swap - these should sell for around $800-1200 if you get one from a junkyard. All 1995-1999 M3s used essentially the same bits, with the automatic cars having a different gear ratio than the manuals. We've used these with up to 490 whp and 315mm Hoosiers without breakage.

The 1997 M3 willingly gave up it's rear subframe assembly, chock full of dusty but stronger M3 goodness

We also managed to get some good OEM M3 bumper covers (front and back), side mirrors, seats, door panels and a few other cosmetic pieces. Much of this will be used on the ST2 chassis, which was a plain jane 1992 325is with an open diff and itty bitty brakes.

The guys cleaned up the interior, washed the exterior, swapped the parts with the 325's subframes/suspension/brakes/wheels, bled the brakes, and we put the 97 M3 up for sale on Craigslist for $700. I figured this clear titled, rust free M3 chassis would sell easily. Nope. Weeks go by, no calls. So we lowered it to $500. Nope. Then some friends came buy and bought the front grill surround and radiator support for $200, so we dropped it to $300. Finally got a buyer when we dropped the price to $200...?! Sheesh, tough season to sell cars, but at least it is gone AND we have a truckload of good parts to use on the ST2 build and even more bits to sell off separately.

We took our body dolly and modified it to fit the E36 chassis. You see we often get cars stripped down to the tub (to work on or replace the front and rear subframe crossmembers) and need a way to secure them to a mobile table, so we built the dolly. Then for each new chassis we use it on we make crossbeams that attach to the chassis in some way. The E36 crossbeams attach to the four "T-hook" mounts common to all E36 unibodies. Once bolted in place the chassis can't come teetering off the dolly, and it can go on and off quickly.

Subframe Reinforcement Work

With the chassis secured to the dolly we could then remove the front and rear bolt-on crossmembers, which went onto the 1997 M3. The M3 has a unique rear crossmember (it is stamped "M3" and probably has more steel in it than the non-M), which we stripped down to the core fabricated steel. The front crossmember was similarly deconstruced, and the control arms, uprights, swaybars, steering rack and differential housing were removed. These crossmembers were then dropped off at CrossLink Powdercoating in McKinney, where they glass bead blasted the subframes down to the bare steel.

The front crossmember (above at left) looked fine, and there is no "M3" version, but we wanted it in bare steel so we could reinforce it. This work consisted of our fab guys stitch welding some items in the fabricated factory steel assembly that otherwise had no welds. Other areas that were already "stitched" were instead seam welded, to add rigidity.

An E36 Front Subframe Reinforcement Plate kit (link) from RallyRoad was then welded in place. This kit includes two different types of laser cut plates. The first part goes under the stock motor mount plate (the top piece), shown below left. This more than doubles the thickness of this location that is reported to crack easily. The second laser cut plate spans a large open gap on the bottom side of the crossmember, under the main motor mounting hole. Both of these plates were fully welded in place.

The rear subframe got much of the same attention. Unwelded seams got some stitches of welds and stiched portions got full seam welds. We also added a 2nd RallyRoad reinforcement kit of more laser cut parts, shown below left. Normally the OEM style rear swaybar mounts off of two tabs that are cantilevered off the back of the rear subframe. This RallyRoad kit beefs up the rear swaybar mounting position on the rear subframe, triangulating and boxing it all together. I don't have a great picture of this installed, but you can see this boxed section in the below left picture.

After the subframes were welded up and reinforced we sent them back to the coater for a shot of gloss black powder coat, which is super strong and last much longer than wet paint. While the subframes were still out the crew here at Vorshlag reinforced the rear subframe mounts and RTAB buckets on the chassis.

The RTAB buckets in the chassis can rip out under extreme loads (giant R compounds + lots of power) so we used another RallyRoad laser cut kit for this section. This "C" shaped piece of plate steel is precision cut to go around the front mounting hole for the rear trailing arm. To install this the chassis was stripped of undercoating and paint, the entire section was seam welded then ground flat, the RallyRoad laser cuts were bolted in place, then they were fully welded around the perimeter. There are also 3 open holes in the C-channel where rosette welds are added. Then this entire area was sprayed with self etching, zinc based primer.

Another area of potential failure on non-M E36 chassis (and all E46 chassis) that you always need to address (dual purpose street/track or full race cars) is at the rear subframe mounting positions on the unibody. These mounting points can crack and even rip out (not pretty!) under lots of load (grip + power) as well as from normal street driving if you have worn rear subframe bushings (they all wear out). BMW figured this out and added double-thick reinforcement plates to the E36 M3 chassis at the factory. These stamped steel plates can be purchased from BMW, which is where we got the ones from this car. The entire subframe has to be out of the car, then these areas have to be stripped to bare steel, these plates seam welded into the 4 mounting positions, then primed with the self etching primer. A must for all non-M E36 cars.

Pictures showing E46 BMW rear subframe mount damage (left), then repaired/upgraded by Vorshlag with a Turner reinforcement kit (right)

This is a chronic problem on ALL of the BMW E46 3 series chassis (see the cracks in an E46 M3 we repaired recently, above), as BMW neglected to reinforce these chassis at the factory and the used seemingly even softer rear subframe bushings. BMW lost a class action lawsuit due to this issue with the E46 chassis, too. We've seen entire trunks ripped out when this problem was ignored for long periods. We do a number of these E46 rear subframe mount repairs and reinforcements every month here at Vorshlag and after dozens of these repairs we have never seen a car that DIDN'T have cracks in the chassis - even super low mileage, totally stock cars. 100% failure rate on the E46.

More E46 BMW rear subframe mount repairs/upgrades

We only recommend using polyurethane subframe bushings for the E36 and E46 chassis, from sources like Powerflex; do not replace worn out OEM rubber bushings with more rubber bushings. We are a stocking dealer for Powerflex and they offer two types for the E36 chassis: the Purple street and Black race versions. The E46 above had some of the streetable versions, which are still considerably stiffer than the OEM rubber bushings. The stock rubber bushings have large air gaps and allow for far too much subframe-to-chassis movement, which eventually causes the chassis cracking problems.

On the ST2 E36 rear subframe (above), after this piece came back from the powder coater we installed the Race (black) Powerflex poly mount bushings. These are pretty stiff and only have the slightest NVH reduction over aluminum mount bushings. The diff cover mounts are aluminum and were sourced from Turner.

continued below
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Unread 11-21-2013, 05:52 PM
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Default Re: Vorshlag BMW E36 LS1 "ST2 Build"

continued from above

Chassis Reinforcement and Prep

While the rear subframe was out being welded/reinforced/powder coated, and after the RTAB buckets and subframe mount reinforcement work was done, it was time to pretty up the rear of the chassis. The guys degreased, power washed, paint prepped, stitched welded a few areas and then painted the back of chassis in high gloss white. A lot of hours went into this step but the results were worth it.

Since we might cut out the spare tire well (one of the few parts of the floorpan legal to modify in Super Touring) I had the guys leave that section unpainted. And since we still have cage work to do in the middle of the chassis, they stopped the white paint forward of the RTAB buckets.

On the front of the tub the guys stripped and stitch welded a few more areas of concern, like places normally only held together by spot welds. After that the same power washing, degreasing and paint prep were followed by more gloss white paint. This is a paint product we've used before and it is tough stuff. It rolls on, not sprays on, and takes about 3 coats to really get perfect coverage. It is so nice working on a super clean white chassis like this, and the exterior will be spray painted a matching GM Gloss White as well. We will eventually paint the cage and interior with some more high gloss paint, too.

Cage Work Started

Since this will be built to ST2 rules, which is a wheel to wheel club racing class, it needs a full roll cage built using the specs within the NASA CCR. I'm not going to bore you with all of the possible roll cage tubing sizes we can use other than to say that since this car will be between 2500 and 2999 pounds we will use 1.75" diameter x .095" wall DOM tubing (see NASA CCR, 15.6.18 section).

Before we began the cage work the interior was stripped, of course. Strangely we didn't get pictures of any of this work. Tons of carpet, heavy foam insulation and wiring came out. Then the dash and HVAC bits. Not a single picture, which was puzzling. Anyway, even with all of the interior panels and carpet out there is still a lot of "sound deadening material" that is stuck to the floorpan in large areas. Kyle worked for a full day getting this stuff out, using two popular methods. The method shown above was taking dry ice and placing it on the thick insulation material.

In theory (internet theory, mind you), after you place dry ice on top, the black sound deadening material then gets very cold and brittle and you just "tap it with a hammer and it pops off". Well, that did not happen. This dry ice method is terrible and I would never recommend it to anyone, at least not with a BMW. We had much better luck with heat, namely using a heat gun to soften the adhesive then peeling the material off with a scraper. Of course when you do this the factory paint under the material gets scraped up a bit, so we cleaned then primed these areas to prevent rust during the next few weeks of work.

While our head fabricator Ryan was on vacation for a week and a half we took the stripped chassis over to Janco Fab and had Kurt bend up some of the .095" wall DOM tubing we brought. Kurt bent the main hoop and two front A-pillar bars above, which came out great. Janco does this type of cage bending work for a lot of shops in the area and we will continue to use him, because he is damned good. We had our friends at Titan Auto Glass come by and remove the windshield and rear glass, to make the cage fab work easier. Of course the windshield broke, but that happens a lot on original glass bonded to a chassis that has been installed for 22 years, like this was. At least the more costly rear glass was intact (although we might use Lexan back there and the rear quarter windows, depending on where the weight ends up.

Once the car was back from Janco the guys mocked up the bars he bent up and they began to work on the mounting plates that will be welded to the chassis. These load spreader plates will be made of .125" thick steel, which is thicker than the .080" minimum thickness (see NASA CCR, 15.6.14). Ryan here at our shop will build the rest of the cage structure and do all of the TIG and MIG welding.

This build will have a somewhat minimalist cage; one that meets the CCR and has a few optional tubes and gussets, and NASCAR style door bars on both sides, but nothing like the overdone cages I see "designed on the internet", with 20 optional tubes and X-braces on top of X-braces.

The pictures above show a cage built for us by Dallas Performance back in 2007, which was not made to be W2W legal, but was fine for Time Trial use with only a driver. This ST2 car's cage will have NASCAR style door bars (on both sides) instead of the X style door bar shown above, and we will add an FIA bar to support the front corner of the cage as well as several gussets. But for the most part it will be similar to that one, which was plenty strong, safe and fairly light. No bars "going nowhere", unsupported nodes, bars to the subframe mounts or the like.

What's Next?

We have plenty of work to tackle in November and December to make our first scheduled January 2014 race date. Here's next year's NASA schedule that we are trying to run in TT2, which just came out:

January 18-19............MSR Houston
February 15-16...........Barber Motorsports Park (MS, SE and NOLA regions)
March 8-9................MSR Cresson
April 25-27..............Texas World Speedway

June 21-22...............Hallett Motor Raceway
Aug 1-3..................Road Atlanta Nationals Practice
August 29-31.............NASA Eastern States Championship at Road Atlanta
Sept 20-21...............NOLA Motorsports Park (crossover w/ MS & NOLA)
October 11-12............Texas World Speedway
November 1-2.............Eagles Canyon Raceway

The dates in green above are the ones we will likely run in this LS1 BMW car. After about April 2014 we think the new 2015 "S550" Mustang chassis should be out and we will try to acquire and prepare one of those for the rest of the NASA races in 2014. Amy and I are signed up to run as a "team" for NASA in 2014 (Team Vorshlag), so we can share a car and only pay a single entry fee. It makes more sense than paying for 2 entries and sharing a car anyway - its not like we will get any less track time. When the Mustang arrives and is prepped, we can switch from this E36 to that, and say in TT2. That's the plan, at least...

A few other bits have been finalized. We just ordered a set of 275/35/18 Hoosier A6s for this car and the Forgestar 18x11" F14 wheels will be ordered soon. This 11" wide wheel will let us run as narrow as a 275 or as wide as a 315 tire. Of course there is a nice weight break at 275mm, so we will build around that primarily, but the flares will be built around the optional 315 tire, just in case. Its nice to have some flexibility down the road.

What will it weigh? Here's an idea...caged LS1 E36 without driver

Weight and power are the last things we will finalize. The power can be adjusted with a few parts changes (cam, intake, tune) so the final race weight will kind of end up being the driving force for that. We know what a similarly prepped E36 LS1 should weigh, because we've built them before. The E36 above had stock M3 brakes, a cage, all steel bodywork, all of the glass (except doors), heavy wheels and an LS1 + T56 and was 2508 pounds, with a single seat. In ST/TT classes you weigh with driver, and since I'm 200 pounds, that puts us near 2700 - soaking wet, without any significant weight savings plans (lighter wheels, brakes, bodywork, Lexan, etc). I don't see this ST2 chassis being much if any different... maybe 20 pounds more cage material, at most? Since the ST/TT "numbered classes" (see this page) are almost all "power to weight" based we can adjust the weight or power as needed to stay in ST2/TT2.

Essentially we are building towards an 8:1 pounds per horsepower ratio, which is the limit for ST2 and TT2 (TT3 is 9:1 or 9.5:1 if you have non stock aero, and TT1 is 5.5:1). There are several "modifiers" to this ratio, of course, and this car will use two of those. First, staying with a DOT tire that is 275mm or narrower gives us a modifier bonus of -0.4, so that would be 7.6:1. But then you have to look at your final race weight, and if we run it from 2651-2750 pounds (very likely) we would have to take a +0.25 ratio hit, which puts is at 7.85:1. So with a 2750 pound car in TT2/ST2 we would end up being able to run as much as 350 whp, which should be pretty easy to get to in a nearly stock 5.7L LS1 we have in store. A bone stock junkyard LS1 with our kit headers made 340 whp in a previous build, and the motor we are using is similar, but has been rebuilt by HKE.

That's all for this time. We should have more frequent updates over the next couple of months. Thanks for reading.
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