Im not sure. Honeslty, like I said this is my first forced induction build with anything porsche related.. Iam also not sure if I ever asked this guy how much power his motor runs now..

Either way, I guees this is something I need to look into further, im not interested in crushing a ranny while rolling down the road.

If he's CIS with common build parts, he's probably at (more likely past) the limit of what that 915 can handle.

I am EFI and going with a single GT35R and will be over 500 CHP. I am at 400/400 RWHP with the modded turbo that I have and I am running a G50 that is close to it's limit and will be doing a billet diff cover soon.

I can tell you with my G50 and 400 tq @ 4000 RPM it will break the tires loose in 2nd gear when I hit full boost. This happens at 40 MPH with 315 and LSD

okay, i see. Ive done alot of research but I think this thread gave me a bit more direct information so far then all the back and forth talk I have heard before. I will have to consider some more changes I think.

Here's the G50 spec

1st gear 3.500 (3.154 G50/02)
2nd gear 2.059 (1.895 G50/02)
3rd gear 1.409 (1.333 G50/02)
4th gear 1.13 (1.074 G50/00) (1.036 G50/02)
5th gear 0.89 (0.861 G50/00 and G50/02)
Final drive 3.44, 7.5”

And now a 915

1st gear 11:35 (3.18)

2nd gear 18:33 (1.83)

3rd gear 23:29 (1.26)

4th gear 27:25 (0.92)

5th gear 29:21 (0.74)

Final drive 7:31 (4.42)

So the gears on a 915 are even closer when you look at the final drive numbers.

CMS used to have some speed charts for the G50's and 915 but I can't seen to find them.

PORSCHE TRANSAXLE TECHNICAL INFORMATION – California Motorsports Inc

Ive gone through two 915's w/350 lb ft torque and that was with an 8.31 915. I'd say you have the shorter weaker 915. Forget that trans as it will break quickly. Sorry to be the buzzkill. You can do twin turbo but it better not go over .65bar. It might look genuine and it will be quick with .65bar but it won't be much faster than a regular 930 stock in performance.

well thanks again for all the information. So I guees its best I find a g50. So is there honestly a short g50 that is possible to fit without chopping out the torsion bar housing?

I just love how some people say these trans can handle 450 all day long. And then the real guys who do the work them selves and know what there talking about tell me the information you guys are saying. I am a person who has always done everything myself, as I am doing so on my porsche as well. But yea I was lead to believe the 915 can take more then what is true i guees

SHORTEN BELL HOUSING AND INPUT SHAFT – California Motorsports Inc

Well looks like I have a rebuilt 915 for sale. Time to start looking for a g50,,,and doing this short bell housing route...

it's a slippery slope.... 2 turbos, G50... are you going CIS or EFI?

EFI, using what I can from the original carrera 3.2 stuff. adding and changing a few sensors. But the motor was a 3.2, just added some ARP stuf and 3.3 pistons and cylinders.

OH sorry, but it will be going standalone

Oh, then you will for sure blow up a 915!!!

You will need more than just a trans for the G50 swap though.

You will need
Trans
shifter
shift tube
clutch slave
clutch master
clutch line (or fabricate)
peddle cluster for hydraulic
fly wheel, pressure plate and TO bearing
clutch fork

I looked for a wrecked G50 car at auction and sold off all the other parts. Ended up with the trans and related parts for under $2k

yea I figured all the other parts will be needed. hahah well anyway thanks for the directions, some good info here. What are 915's worth now days, I have $2500 Canadian invested in mine, including the rebuild. Thats not bad I guees.

You might also look at a 930 trans as there are fewer things to swap out. You'll still need to shorten It though. But it the right trans for a 934.

did the 930 trans also use the 240mm clutch setup...instead of the 225?

CMS has all the info you need man...

PORSCHE 930 TRANSAXLE SPECIFICATIONS – California Motorsports Inc

Yeah it's the same 240 size. Has the same/similar strength.