I brought my "new" S2 race car to a PBOC event at Road Atlanta for its shakedown cruise. I was a little disappointed in its performance, especially down the back straight. My previous car was a 2.7L 944 8V GTS1/SP2 car.

In fairness, the car has not been aligned or corner balanced since suffering a minor accident with the previous owner. This and my unfamiliarity with the car partially account for lap times only marginally better than the 2.7 NA. None of this should greatly affect speed down the back straight. I would expect that 50 more WHP would result in a higher top speed. My 8V usually hits about 122. the 16V only hit 124.

I suspect the difference is the ratios in the S2 transmissions vs the 8V short 5th box in the other car.

The differences are as follows: Final drive 8V 3.889 16V 3.875 5th Gear 8V .829 16V .778

The car just doesn't seem to pull well coming out of turn 7.

Looking for comments. I would also like to know whether an 8V transaxle will hold up the S2 16Vs power, or should I consider putting a shorter 5th into the 16V (AOT) transmission.

 

You should be closer to 140. I was over 130 as a first time solo driver in my Turbo when it still had full interior and a catalytic converter! I'm wondering if you are down on power. Way down.

 

The car feels pretty strong except on the back straight. i have a Dyno appointment on Wed. The last Dyno sheet I have showed 201 WHP 206 torque. Its hard to compare a Turbo with an S2. Anyone out there with some S2 speeds?

 

How fast were you going when you spun it Harry? I know, I'm such a jerk.

 

That was Hal's, not mine I think about 115, but I let off before the black flag.

John, the Turbo has taller gearing, and similar power/torque. I actually have an S2 LSD I'm hoping to put in before the March race. They are pretty close, but in both E and SP3, the S2 is pretty dominant. There is no way my bone stock car with a 130,000 mile cat was making 201 horsepower at the wheels!

 

I guess the Dyno will tell the tale. I'd still like some S2 speeds and views on gearing.

 

I think Karl gets a little over 140. I've got some gearing spreadsheets I'll try to dig up that have engine RPM, vehicle speed, and gearing. I know that I have to shift into 3rd coming out of 7 before I finish tracking out in my Turbo. But I have no idea what speed that is. I know it isn't an S2, but considering how far off the speed is, it should still serve as some sort of comparison. Not sure how that compares with your exit speed out of 7, I would expect you are in 3rd the whole time?

1-4 are the same between teh two gearboxes. The S2 has a 3.88 R&P, whereas the Turbo has a 3.38, so you are shorter by the same ratio in every gear (up to 5, where the S2's gear is taller than the Turbos - but not by as big a differece as the R&P)

 

Some charts to ponder.
Hmm, sorry I thought I had an S2 chart as well? Anyway this might give you a couple of clues.

 

The Turbo S2 final drive one is the same in gears 1-4. Top speed at 6500 RPM in that is 148-149MPH, so that should help visualize it.

 

I've edited my above post to show the stock S2 gear chart.

 

Yes, you're spot on. Gears 1-4 same with turbo w S2 r&p. Just a longer 5th with turbo.
(I'd actually like to get a different r&p for my 6 speed...but that's a different matter.)
Sounds like John has a strong S2 motor so perhaps it's just 'one of those corners' where you're just inbetween ideal ratios?

 

What' a 124? I would have to hook on to carrera coupes bumper to see 119 going into 10A.

 

Thanks for all the help. I see a few things:

1. The tire diameter is a lot bigger on the 16V 285/30/18 24.9" 8V 275/35/15 23.0"

2. The 5th gear ratio is higher on the 16V .7778 8V .829

3. The final drive ratio is also higher on the 16V, but not easily fixed without giving up the extra strength of the S2 R&P.

I think I'm concluding that the easiest fix is to swap in a turbo .829 5th gear set.

I also discovered that I was running a stock chip. The modified chip I have, doesn't change the Max HP or Torque, but adds a little more mid-range torque.

My 2.7L 8V pulls like a freight train out of 7. The back straight is one of my favorite passing spots. I just need to sort the S2 out so it does the same.

 

You know what you need to rectify that situation, don't you? A 968! Preferably a red one.

 

John,

Nice to see a picture of the old girl. Even the butt dyno will tell you that the box tuned by BEHE is much more robost. Not sure it gives you more top speed, but you'll feel the torque. Please do not mess with it and tune up the stock one as I understand you will not be running in E stock. BEHE tuned the box to provide the best ratio of performance and safety parameter.

I have the transmission you want sitting in my garage. You will not be getting one built for the asking price. I'm sure if you shake the couch cushins, you would come up with enough change.