924/944 Racecar Weight Reduction

[michaelmount123]

I've always been curious why folks can't get weight (way) down on the 924/944 chassis. Based on what I read on the forums, folks are thrilled to get to 2200 or 2300 pounds after lots of effort.

Back in the day (okay, maybe it was WAY back), I ran a 924 D/P (933) chassis with a 2.8L 4V NA engine very successfully in PCA Racing and local PCA time trials. At the time, there were no minimum weights and classification was by displacement only. My car weighed in a 1970 lbs. wet sans driver and was a consistent race winner and frequently overall FTD in timed events. The light weight configuration not only allowed it to be quick, but also enormously fun to drive and be be very easy on mechanical components such as brakes, suspension, gearbox and such.

Admittedly today's race classifications typically include minimum weights which preclude super lightweight stuff, but outside of proper racing there's plenty of reasons to go lightweight. I know of one project 924 being constructed at the moment by a shop that has my old car and another 933 under the same roof. They are putting a lot of effort to minimize weight and I'm very interested in the outcome since this car was originally a street car. I'll encourage them to publish the results and include some detail on their weight saving efforts. Stay tuned, I hope.

IMG_3080.jpeg (380.64 KiB) Viewed 975 times

[Pefa]

Hi Michael.

Would love to know more about what you did to lower weight to get to 1970 pounds!
Also general specification on your old car would be interesting

You know about my 924 "RS" project that went up in flames but I still have the engine and some parts for it and the idea is still alive in my head.
Would love to get a streetlegal car really lightweight with that engine in it.

Thanks
//Peder

[endoquest]

Michael: My amateur club racer efforts in SCCA E Production and ICSCC rules have gotten me down to the minimum weight of 2250lb with driver (180) and 2 gallons of fuel (12) at the end of a race. This is with an N/A 8V, 260HP motor.
So the car weighs 2058lbs empty, putting me 90 lbs more than your 924 back in the day. (Beautiful pic btw)

1987 tub, spec roll cage with LOTS of holes, fiberglass, lexan and missing parts. 7X15 cookie cutters with 43mm spacers (16lbs), light engine parts too.

To answer your post question, it's all about the rules and if you have to follow them. The current SCCA rule set makes it pretty difficult to make an 8V 944 2250lb. Things were different 30 years ago. The caveat is MONEY!

Unfortunately, even money won't make an $80K 944 competitive to a $40K BMW Z3 now.

BTW. Thank you so much for the cylinder head work you did last year. Two track records and a 2nd place championship were the result of a great motor. Cheers

[333pg333]

I've often wondered how some people can get their cars down so light? 1970lbs is feather light in my book Michael. My car with single skin metal roof, f/g quarter panels at all 4 corners, f/g nose and bumper. Carbon doors and hood. Lexan rear hatch. Glass front screen as part of rules. Aero add ons such as dual element carbon rear wing. F/glass rockers. Ply splitter with alu end fences. Air Jacks. Dry sump. Larger cooling cores. 18" x 11.5" wheels at all 4 corners. 6 piston front calipers over 375mm front rotors. Pretty decent sized turbo and s/s headers. Plus other bits n pieces. If I remember correctly the car weighs (with all fluids and a few gallons of fuel) 2550lbs. That's a LOT more than yours. Guess it all adds up. Assuming you had Lexan front screen. That must weigh a fraction of the stock glass version.

[michaelmount123]

Porsche Weissach gets all the credit for the lightweight 924 D/Production (933) chassis. Only 16 were built to bring awareness to the new front engine model and Porsche put serious effort into the program. Here's lots of info on the cars and the program: https://www.stuttcars.com/wp-content/up ... uction.pdf

My car was one of those chassis. I put lots of effort into maintaining the very low weight as I upgraded to a 944 4V NA engine, 924T driveline, bodywork to accommodate wider rubber, and ultimately aero. It embarrassed a lot of 911's and turbo cars back in the day.
MM

[333pg333]

Porsche Weissach gets all the credit for the lightweight 924 D/Production (933) chassis. Only 16 were built to bring awareness to the new front engine model and Porsche put serious effort into the program. Here's lots of info on the cars and the program: https://www.stuttcars.com/wp-content/up ... uction.pdf

My car was one of those chassis. I put lots of effort into maintaining the very low weight as I upgraded to a 944 4V NA engine, 924T driveline, bodywork to accommodate wider rubber, and ultimately aero. It embarrassed a lot of 911's and turbo cars back in the day.
MM

That's an interesting article Michael. I hadn't heard of these or at least in any detail. That must have been fun developing and racing the car. Especially when you upgraded to the 944 16v motor. What sort of hp were you pulling out of that? Must have been a noticeable jump from the 2lt 8v version. Do you recall the compression ratios?

[Lowencash]

1987 tub, spec roll cage with LOTS of holes

I'm surprised that this would be allowed.

[michaelmount123]

Porsche Weissach gets all the credit for the lightweight 924 D/Production (933) chassis. Only 16 were built to bring awareness to the new front engine model and Porsche put serious effort into the program. Here's lots of info on the cars and the program: https://www.stuttcars.com/wp-content/up ... uction.pdf

My car was one of those chassis. I put lots of effort into maintaining the very low weight as I upgraded to a 944 4V NA engine, 924T driveline, bodywork to accommodate wider rubber, and ultimately aero. It embarrassed a lot of 911's and turbo cars back in the day.
MM

That's an interesting article Michael. I hadn't heard of these or at least in any detail. That must have been fun developing and racing the car. Especially when you upgraded to the 944 16v motor. What sort of hp were you pulling out of that? Must have been a noticeable jump from the 2lt 8v version. Do you recall the compression ratios?

I had several engines in this car over the years. I began with a 2.5L 944 2V on carbs, then went to a 2.7 4V and ultimately to a 2.8L which was the class limit at the time. I ran the c/r around 13.5 and dug up some old dyno sheets which showed 317fwhp. This was in 2001.

Interesting to note the "kit" of boxes from Porsche cost $40K usd in 1979 which is equivalent to around $178.5K usd today. They were sitting around unused for many years and dirt cheap, but have gotten quite valuable recently.
https://www.broadarrowauctions.com/vehi ... production

[michaelmount123]

Here's a 933 assembled, but never run:

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[333pg333]

$150-$200k is some serious money right there! Are there vintage racing classes where these are still highly competitive? Otherwise that's 'real fan' money they're asking. Bet they were a ton of fun to drive. Very light and responsive with some decent power to weight ratio going on there.

ps...are you still working on the Technodyne car?