User 52121

Very possible. I came up with the formula a long time ago. Also note the tire radius is for a Yokohama AD08 in 285/30-18 so your numbers using stock tire sizes might be different.

It still works as a good comparison across the different transmission combinations.

If you have a better spreadsheet please do share.

333pg333

I was just using Gearcharts that I've accumulated over the years. Good reference being off California Motorsports website. Click on each gearbox and there should be a chart to view.
http://www.californiamotorsports.net/

C ANDERSON

Just put an S2 trans in my modified 951 and so far love it, no lag any more, lot easier to drive in town . Still have a 951 with the original trans that is just lightly modded for highway use. Also have a S2 that has always been my favorite all around driver because of the gearing.The one in my avatar . Going to BARBER with the new trans in June so we will see.
Clifton

333pg333

Generally the O.D. of the tyres is very similar so the speeds / rpms shouldn't be too far off between sizes.

lart951

okay, I have the same dilema, I have a choice between the S2 tranny and the 968tranny, for my boys car he is seeing peak power around 4500rpm so by reading this it's my understanding that the s2 tranny will be a better choice for a street car/ highway car

dp951

Ive uesed all 3 boxes in my turbo 2.5 as well as my 968s I my opinion for the short halls the s2 or the 968 boxes are nice for car that see's lower rpm performance, the acceleration feel is excellent spool up is quick . The 968 box behind a performace 2.5 or 2.8 is not much fun unles you like to shift allot and fast , ( wasted rpm ) the gear ratio is better suited for cars in the lower hp levels as well as the gearing .

The turbo box is well suited for the expressway junkies , the ratio is suited for the higher speeds with less rpm useage. (as stated above the cruiseing rpm speed with the s2 is higher )

But if your looking to burn tires and feel a nice pull around town or auto crossing then the s2 is a nice choice, I my opinion they stand up to the rigors better than the oem 6speeds.

street or auto c S2 or 968 (oem)
highway Turbo (oem) or mod 968 ( gears changed )

lart951

okay so theoretically speaking if I were to run against LS powered car with similar hp than my car in a simulator from 40-120mph which tranny would be better suited?

Ben951S

Is this right? If so, my AOR trans has an S2 R&P in it? I'm a hair above 3000RPM at 75 in 5th....

??

333pg333

It may well be partially an illusion as the turbo with S2 rp 'feels' a lot faster but you do change gears a bit more. It definitely feels better around the track and even spirited street driving. The standard 951 gears seems best suited to high speed Autobahn bombing.

azbanks

Has anyone swapped the taller S2 AOT R&P into a turbo AOR box?
I do a LOT of highway miles and would like to run lower revs while cruising?

User 52121

Maybe I'm misunderstanding the question... but an S2 R&P in a AOR box would be worse for what you want.

The standard turbo 5th gear is shorter than the one in the S2. You'll be revving higher on the highway with an S2 R&P in a turbo box.

If you want lower highway revs, you want the full S2 box. It's for this reason that I did a full S2 box in my car instead of just the R&P swap. I commute in my car on warm days and didn't want the motor buzzing along at higher revs as I cruised on the highway (sucking more fuel!)

blown 944

You want the early NA 5th gear.

Luis, if you are truly looking at LS power, then IMO you would want to stay with the turbo box.

Mr.C

So if I understand correctly the S2 ring and pinion is best for AutoX? The courses I run locally always seem to be set up for Miatas, so Im bumping rev limiter in 1st or lagging in 2nd. Mileage is a no issue since I currenly trailer it everywhere.

User 52121

I AutoX my car a LOT. I swapped the S2 box in and LOVE IT.

1st gear is SUPER short... but 2nd is perfect. Faster courses have me up into 3rd. Previous years the course had to be almost silly for me to need 3rd (with the turbo box). This year I was into 3rd on a couple different courses.

Mr.C

Cool that may be my ticket then. I was 2sec off the TTOD behind a modified Sti the last time out, which is huge for me. Best part was I had the sti driver in my passenger seat with a huge grin on his face. I now know its possible....having a mustang driver design the course helped too.