Hello,
The SCCA is putting together a new autcross class called STR. The 80's era 3.2 is the only 911 allowed in the class, along with the Honda S2000, Mazda MX5, Nissan 350Z, and Toyota MR2 Spyder.

I think a 911 would be a really fun car to put together for the class. I've been researching the cars a bit but there is some stuff that you can't get from the spec sheets. Would appreciate any input the community could provide.
Here goes-

1. Engine mods allowed are a cold air intake, headers (must retain cats, but they can be high-flow), cat-back exhaust, pulleys, and ECU tune. Everything else stock. Does 190-200ft-lbs. between 5000 and 6000 rpm as a peak torque range, to the wheels, sound about right? The '88-'89 G50-trans cars all had 3.444 final drive with 2.059 2nd gear right?

2. We're allowed wheels up to 9" wide and tires up to 255 in width. We can roll fender lips and have freedom over ride height and alignment, but can't flare. I don't think fitting the max allowed in the rear will be a problem, but what about the front? Maybe it won't "need" as much in the front but it would be good to know what can be done. This'll be a race car/toy so some rubbing is ok, and it won't need full steering lock. Assume this is a regular narrow-body car, not one with the widebody option.

3. The Club Sport is allowed in. I know finding a real one is basically impossible and turning one into a racecar would be heresy, but we are sort of allowed to do pseudo-conversions in some cases. Are the 911CS engines really any different than the standard 88-89 engines, other than ECU? If you took a regular '88 coupe, removed the AC, sound deadening, rear seat, welded up the sunroof panel (or can you get one without sunroof here?), and swapped in manual windows and locks (and headliner I guess), what big stuff would still be different from a Club Sport? I know there was little stuff like the tach and gearshift.

4. With all that stuff done, what's a realistic race weight for one of these cars? The interior would otherwise be intact, but there'd be lightweight race seats, steering wheel, battery. No roll bar or anything as this'll be for autocross only. Is 2400 out of the question? Does the car fuel starve in sweepers when low on fuel?

5. I know these cars weren't meant for drag racing but some of our events feature drag-race starts. How reliable is the stock G50 trans and its halfshafts in this situation, with the power and weight as described above? The 255 street tires would be 140-treadwear "street tires", though the perfomance level of the really high-end 140 tires is approaching the grip levels of R-compounds from not that long ago.

Sorry for my first post here being so question-filled. I promise I've done quite a bit of searching to get this far in research. Greatly appreciate any input you can provide.

--Jason Rhoades

 

Just a wild guess but it will not be that competitive or a consistant leader in that class. The box, G50 or 915 is no where in the league of some of the other cars listed. So you'll make maybe 200+/-hp with a 2600 - 2750lb car, but it's a decade+ older than the other cars. If you want a competitive 911 you can build one but I would think some of the other cars would be better choices to win. Yes the 9x16s will fit easily, 7"s up front are probably the max. I am not saying it would not be fast and in the hunt just probably not the first choice unless you wanted a Porsche.

 

Thanks for the reply teamfee3.

I'm curious on the weight - if one were to basically replicate a Club Sport, then do lightweight race seats, battery, wheels/tires, suspension, steering wheel, etc., would the car still be 2600+? I was thinking/hoping it could get under 2500, sans driver of course.

 

Go to the Pelican Parts forum, lots of stuff there on the 911 froum about weight reduction, some really good stuff in fact. Very active board.

http://forums.pelicanparts.com/forumdisplay.php?f=8

There is a guy who had a topic something like, how I lost 400lbs in a weekend or something. That's the place to post this.

 

3.2s can be built to be very competitive. What you propose is similar to the PRC spec racing class that is popular on the West Coast, that consists of 3.2 and 3.0 SCs. The 3.2s are internally and externally limited to stay as stock U.S. spec, run on 91 octane pump gas, and with some smallish headers and an ECU tune, make a true 250 hp. You can strip these cars down to 2300-2400 lbs. The tires have also been limited to hard wearing Toyos which make a very affordable low stress track car. The September issue of Excellence has a detailed comparison between a 07 GT3RS, PRC spec 3.2, and 09 GT3 Cup. At Thunderhill, the difference between the GT3RS and spec 3.2 was only 1 second.