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lbp
09-25-2009, 04:06 PM
Hello all,

I've been running an '89 Porsche 951 in PCA GT3 category, recently re-classified to GT2 (rule changes).

I'm considering moving, with an SBC conversion, to NASA's SU (Super Unlimited) class which allows just about any vehicle setup.

To be competitive there I would need a minimum of about 600+- up to 750hp with a total vehicle weight of around 2250lbs.

The vehicle weight is OK at 2250 as currently setup with a dry sumped 951 package.

Here are some questions for all Hybrid Guys, particularly if you run a competition-prepared 944/SBC (anyone out there?):
1. Any opinions as to a kit, which is suitable for track competition, to accommodate the LS-7 SBC?

2. Currently run a 6 spd LSD 968 transaxle (with cooling) which has been OK at 550hp.
- Will this transaxle be OK at 600 - 750hp?
- Where is the (HP/TQ)limitation on this setup?
- Also, how about the torque tube with regard to power capacity/reliability?

3. Currently run no power steering/no ABS (although looking into Bosche Motorsport ABS this winter) & floor mount AP pedal box which will be retained. SBC will be run without flywheel, i.e., starter ring on clutch.
- Will any existing kits accommodate this setup without (or with) modification?

5. Any weight comparison information on the 951 vs. LS-7? (both being dry sumped, not sure yet if I would run a FI or carbed unit).
6. Current setup includes Tarret F/R sway bars & Moton Club Sport/HR springs. Torsion tube is gone (rear section now boxed), transaxle (& engine) solid mounted, charlie arms, raised front perches, etc.
- Are there any fitment or structural stress/load considerations given the suspension setup/power requirements? (The car already has a highly engineered roll cage).
- Are there areas on the (1989) 944 tub (or other areas) that anyone would specifically recommend be looked at for further reinforced with consideration to the SBC conversion for competition use?

9. Would like to replace the aging GT Racing wide-body kit with something else. Tire sizes are F 305x18, R 315x18 (rear is tubbed). Any body kit recommendations with (this is important) good aero characteristics?

- Any other considerations?
- Anyone out there running a similar (or not) competition setup?

Many thanks for any and all response. - I was really pleased to discover this forum & hope it will be a source of information for this (potential) project.

968ls1
09-26-2009, 02:58 PM
IPB,

Four year ago I built a car similar to what your are asking about but the power level was around 550 crank HP. The car belongs to my brother and is currently for sell on Rennlist if you want to look at for reference. His car similar to yours in regard to the wide body and race prepped chassis. I have used the 5 and 6 speed transmissions and the 6 speed gearing it too short for the wide torque curve of the LS1. I tried for 3 years to get a custom ring and pinion for the 6 speed but it was cost prohibitive, thats when I went to the 5 speed and it works great and I have not had any issues at he 550hp level. I have no experience with power levels in the 600-650hp range so I can't say if the 5 or 6 speed gearboxes will live or for how long. My brothers car has a 383 drysump LS1 that we started with an ARE drysump and modified it for the 951 chassis. He has run it for 4 years now with out any significant issues but is selling the car due to the weak economy. His car weighed 2650 before the conversion and 2600 after, so we lost 50lbs. I could go on and on so if you would like to discuss furter you call me a t 205-566-2245. I did the developement for Renegade several years ago and have personally built 7 of the these conversions and an glad to share anything I have learded.
Regards,

Tom Egan

ernestj911@gmail.com
09-30-2009, 06:58 PM
I believe we can help. Our conversions have proven reliable in the 12hr races. Drop me a line......

Ernie