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Thread Topic: Rebirth of a 2002 GT3 car

Date: 5-16-06 09:30
From: 2002GT3CAR
Subject: Rebirth of a 2002 GT3 car

After 4 or 5 years of sitting in storage, I have finally made it a priority to put my project SCCA GT3 2002 car back together. The car is a roller as it sits now and I am aiming to get this bucket of bolts back together by late summer.

Here are the specs as it was raced a few years back (before I decided to strip it down and fix a few major issues):

1970 BMW 2002
Schnitzer box flares and front spoiler. Glass hood and trunk.
Lexan windshield, side windows and rear window.
Custom DOM cage tied into front and rear shock towers.
Metric Mechanic 2.0L M10 - 230hp @7800rpm & 165tq @5000rpm (9500+ rpm redline)
50mm Webers
Custom antireversionary intake manifold and exhaust headers
14:1 compression
Crower rods
Elgin cam (similar to 316 Schrick)
Modified wet sump with Accusump
Metric Mechanic 4 speed close ratio box
4.11 rear locker diff
Full coilover suspension
All metal bushings/heim joints
4 wheel disk brakes
13x7 aluminum race wheels with 13x20x10 race slicks
Approximately 1800lbs wet

As you can imagine, the car was certainly no slouch when I raced it (only a few times due to several development problems). The biggest issue was the handling, which was terrible despite the light weight, big slicks and coilovers.

Talking with a fellow GT3 2002 competitor, I tracked the source of the problem to the stock rear subframe. As the 2002 was never intended to sit at such a low ride height, the rear trailing arm geometry was totally wrong, causing the car to toe out under suspension compression. The only solution was to totally re-engineer the rear suspension by raising the rear subframe a few inches higher (had to cut out the back seat floor area) and by cutting and modifying the rear trailing arms to allow for more optimal geometry. I also had Jim Rowe at Metric Mechanic build me a special short-neck variable lockup differential to help the car turn in better mainly.

Anyway, after making these changes, the car sat in my garage for a few years, as I had no time to put it fully together again. I now have the time and have decided to develop the car as far as possible on a tub platform.

This past weekend, I dropped the engine/tranny back in and made a to-do list to get the car track ready and more competitive (although it will never be able to compete with full tube frame national level cars).

1) Aluminum racing radiator - reliability upgrade
2) Samco hoses
3) Full dry sump conversion - just bought the parts from VAC Motorsport. With the handling improvements, the modified wet sump will be unreliable and I potentially risk a blown motor. Big $$$ but other GT3 competitors say it is really a necessity.
4) Move motor back 2-3 inches. The GT3 rules allow for the motor to be set back to where the front spark plug is in-line with the front wheel centerline. I can fabricate new motor/tranny mounts pretty easily, and I have to have a new driveshaft made anyway due to switching to a short-neck diff.
5) One piece carbon fiber driveshaft - I've heard mixed results from using a one piece aluminum shaft for that length and rpm. Carbon shafts can spin up to 10,000rpm+ and also help reduce driveline losses.
6) General reassembly
7) Redyno the car to spend more time fine tuning the Webers. I think the choke may be too large and there is a dip in the torque curve between 5000-6000 rpm that may be a mixture issue.

I will post pictures of the car as it sits now and update pictures as my project GT3 racer comes along.

Date: 5-16-06 09:57 From: TMK-001 in Geelong, Victoria, Australia Subject: Re: Rebirth of a 2002 GT3 car
Sounds unreal! Can you post some pics!?! Please! :-) Todd _________________

Date: 5-17-06 06:36 From: Lupin3 in Atlanta Subject: Re: Rebirth of a 2002 GT3 car
I can't wait to see more of this one. Sounds like a great project!

Date: 5-17-06 11:04 From: bmw1602.com in Los Angeles Subject: Re: Rebirth of a 2002 GT3 car
SOUNDS AMAZING!!! pictures, pictures and more pictures PLEASE!!! _________________ 68' 1602 98' ///M3 Sedan 88' ///M3 Sold * 06' ///M3 Competition Pkg Sold * http://www.bmw1602.com/

Date: 5-17-06 05:00
From: 2002GT3CAR
Subject: Rebirth of a 2002 GT3 car

Here are some pictures of the car in various stages. I will be taking some current pictures of the car this weekend. The car now sports a vintage M color paint scheme patterned after the 70s CSL racers.

Here are some pictures that show the car as it was when I bought it ten years ago. Pretty rough.....

Here is a picture of the car undergoing restoration by me in 1996-1997. The engine is the original 1.8L motor that came with it (170hp roughly).

Here are some pictures of the car as raced in 1998 and 2000:

Many, many more pictures to come as the project gets underway....

Date: 5-17-06 06:20 From: TMK-001 in Geelong, Victoria, Australia Subject: Re: Rebirth of a 2002 GT3 car
Thanks for the pics! Keep them coming! It looks awesome! Todd _________________

Date: 5-19-06 11:06
From: Tommy

Subject: Re: Rebirth of a 2002 GT3 car

Looking great! I'm waiting to see project and detail pics. Engine details would be interesting too - 9500 redline!!??

" As the 2002 was never intended to sit at such a low ride height, the rear trailing arm geometry was totally wrong, causing the car to toe out under suspension compression. "

In my experience lowering causes toe in. Also when trailing arms point up towards back causes poor traction. Anyway raising the subframe is the solution and the difference in handling is more than one could imagine.

Tommy
_________________
Racing is Life - everything before and after is just waiting!

Date: 5-19-06 12:37 From: 2002GT3CAR Subject: Re: Rebirth of a 2002 GT3 car
You're right...too much toe in. Yeah, my racer buddy swears that the difference the modified rear subframe makes is night and day. I'll post some pics current pics of the car this weekend.

Date: 5-20-06 04:19
From: mattmcginn in West Hartford CT

Subject: Re: Rebirth of a 2002 GT3 car

Furthering this point with another marque: Most of the cars Auto Associates builds modified pickup points for the (semi) trailing arms that stick up through the rear seat areas. I forgot to bring this up yesterday while we were on the phone...

A lot of guys with 02 street cars will flip the rear subframe bushings to allow the subframe to sit higher in the car to alleviate some of the static camber and and toe-in that lowering gives...but for your car this would not do much as its pretty dang low.

I have seen your car as it currently is-but those old pix are great for giving context, thanks for sharing them. Any pix while it was a B-Sedan in action and do you have plans to build it to fit a specific era in which it was raced?
_________________
Matt McGinn
Sports Car Restoration
www.sports-car-restoration.com
1974 2002 turbo 4290909, resto project, looking for parts
89 M50'd e30
72 Alfa GT Veloce
84 M491 911
68 1600 channeled and flared project
70 2002 flared car project

Date: 5-21-06 03:17
From: 2002GT3CAR
Subject: Re: Rebirth of a 2002 GT3 car

Hi Matt,

Auto Associates actually built my Porsche GT2 Evo replica (off a 77 911 shell) and did exactly that when I went to a full 935 suspension. That car is literally on rails at 2200lbs with 265 front and 345 rear 18" Michelin Pilot Sport Cups. I'm sure the 2002 will be able to outhandle even that car considering that is weighs 400lbs less.

No plans to run the car as a B-Sedan or Vintage car. I've modified the car too far for vintage and GT3 class is really fun in that it is the most powerful "production" spec you can run a 2002 at, short of just doing BMW Club Racing. If I did that, I would have built a turbo M10 or S14 with 500-700hp and bigger box flares.

Date: 5-21-06 05:34
From: GT32002CAR
Subject: Rebirth of a 2002 GT3 car

Here are some updates from this weekend. I laid out a pretty ambitious plan this weekend to: 1) take some measurements for the modified motor mounts; 2) remove the engine and put it on a stand; 3) replace the wet sump pan with the new dry sump pan and install the oil galley plug; 4) fabricate new motor mounts and 5) install the dry sump engine back in the car with the modified motor mounts....Somehow, it went far quicker in my mind than in reality. Only finished steps 1 and 2. Oh well.....

Anyway, I took some current pictures of the car and the wet sump 230hp motor.

Some front shots of the car:

Side pics of the car. The garage was pretty tight so there wasn't enough room to take a full side profile shot.

The rear of the car.

Here is a pic of the wet sump motor installed in the stock location so I could figure out how to modify the motor mounts.

Here are pics of the 230hp wet sump motor on the engine stand. I'm sure the unconventional intake and exhaust manifolds will prompt some questions. They are designed to be anti-reversionary. In truth, I don't think they really add anything in terms of peak power output, but the motor does have a pretty wide powerband, so it must help. Probably more a function of the 316 cams I'm using. I don't buy into that whole 336 Schrick arguement - M10 heads don't flow above .500 lift anyway and all you do is break rocker arms.

Here are pics of my new dry sump pan. I got it from Tony at VAC Motorsport. $600 for a pan seemed expensive, but let me tell you, this pan is a thing of beauty. Moroso makes it for VAC and it looks almost too nice to install in my car. The welding is top notch.

That's all I have for now. Hopefully, I'll have some more progress pics in a week or two.

Date: 5-21-06 11:34
From: bmw1602.com in Los Angeles

Subject: Re: Rebirth of a 2002 GT3 car

love the new paint!

I'm getting ready to paint mine in a similar fashion.

looks like you painted the stripes.....

did you paint the car?

anytips on doing stripes?

if you had it done, how much they charge you?

is it clear coated?

I'm also getting ready to make my lexan front and rear windows. What thickness is the front one? the rear? where did you buy it from? did you have to pre bend it? please give me some tips! If you had it made, who did it for you? how much they charge ya?

The dry sump looks awsome....can't wait to see more updates! keep the pictures comin'!!!
_________________
68' 1602
98' ///M3 Sedan

88' ///M3 Sold *
06' ///M3 Competition Pkg Sold *

http://www.bmw1602.com/

Date: 5-22-06 04:58
From: 2002GT3CAR
Subject: Rebirth of a 2002 GT3 car

The paintwork was done by someone else actually. The car is painted PPG Alpine White and I picked out some PPG colors that I felt were pretty close to the M colors (don't remember which codes I used). The car was painted white inside and out and then the stripes were painted on top. He charged me $2k for the whole job. The paint looks nice at 5 feet which is all you really need for a race car anyway. My only complaint is that the bodyshop did not properly align the front hood like I asked before laying down the stripes. Now I will have to do that and then have them redo the hood stripes again.

The lexan came with the car when I got it so I don't know where you get it. The front windshield never fit properly, so I am considering buying a new one too. The best solution would be a flush mount windshield - there are a few lexan companies that can make one up custom using a glass 02 windshield as a mold. Per SCCA rules, the front windshield must be 6mm thick and the rear should be at least 3mm.

Date: 5-23-06 12:21 From: Tommy Subject: Re: Rebirth of a 2002 GT3 car
The manifolds are really something special. I've NEVER seen anything like that on any car! Would be interesting to see your power and torque curves because my engine is now quite close to yours except the manifolds and you probably have done something more with the head. Tommy _________________ Racing is Life - everything before and after is just waiting!

Date: 5-23-06 05:55
From: 2002GT3CAR
Subject: Rebirth of a 2002 GT3 car

I know that the intake manifold works because we dyno tested it back to back against the regular shorty TWM manifolds. The reason it works is because it prevents the typical carburator fuel standoff that you get from running sidedraft carbs. The headers I'm not so sure about because we never tested them against a good set of conventional racing headers.

On one hand, these headers 100% prevent any exhaust gas reversion. However, the primaries are not even close to equal length and they also have some pretty sharp bends very close to the exhaust ports which is bad of course. If I have time this summer, I am going to fabricate a set of custom conventional race headers using top grade stuff (Burns tubing and collector) just to do a comparison.

While there are guys who say they are making 250hp+ out of carburated M10s, I would venture to guess that they have a very narrow powerband -maybe only 1500rpm between peak torque and peak hp. From what I understand, many of those 250hp motors use a 336 cam, which also poses a lot of reliability issues in terms of rocker arm breakage. My motor, with a 316 style cam, pulls strongly from 5000rpm and makes peak hp at almost 8000rpm. It doesn't post spectacular peak numbers, but it is a very usable power band.

Date: 8-19-06 02:16
From: Mark
Subject: Re: Rebirth of a 2002 GT3 car

I remember that Rick Haner had a car that looked like that (originally) for sale about 10 years ago (I think that was him anyway). As I recall it had a bunch of vintage ALpina stuff on it. By the way, if you still have that seat shown in the picture at the top and want to sell it...let me know. I don't know that I have ever heard of a SOHC M10 motor making 250 hp or even near that even with huge compression and 320-330 cams. Makes you wonder why the factory would invest so much $$$$$$$$$ into multi valve, multi cam motors if they could get that much out of a single cam 8v motor. The most I had ever heard (before this) was about 230 from an Alpina slide injected M10 (12-1 CR) 48/41 mm valves and a 320 cam--that engine was also dry sumped. Good luck with your project and racing in GT3--nice job.

Date: 3-25-07 06:06 From: 2002GT3CAR Subject: Re: Rebirth of a 2002 GT3 car
NEW PICS OF THE DRY SUMP MOTOR!!!!!!!!!!!!!!!!!! Well, its been a while since I last posted on my project blog. New girlfriend + new job since last post = not much time for my GT3 car project :( I did manage to install the new VAC Motorsport dry sump on my motor so I thought I would share the pics. Hopefully, my next post will be a lot sooner than 6 months from now......

Date: 3-31-08 05:54 From: bmw1602.com in Los Angeles Subject: Re: Rebirth of a 2002 GT3 car
that is a sexy lump.......nice. _________________ 68' 1602 98' ///M3 Sedan 88' ///M3 Sold * 06' ///M3 Competition Pkg Sold * http://www.bmw1602.com/

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