Frank@Work

I am going to drop a LS1 engine in my 951. At the moment I am using a S2 LSD transmission which works great for the 951 (keeps the revs within the powerband). It will however be too short for the LS1 (torque everywhere ).

I can buy a freshly rebuild 968 6 speed transmission. Will that be a good choice for the LS1 engine or will it also be too short?

Thanks!

chilibluepepper

excerpt from 968ls1 on Pelican forums:

"The 951 gearbox is the best and will handle the power if don't abuse it, I have used the 968 Trans but the gearing is too narrow for the V8 power curve."

gt37vgt

well you can always cam up the v8 if you like but realy the fist 2 gears perhaps 3 will be usless I would think you will be able to swap your current box with a 951 owner put the word out here on rennlist . and surly you will find a better use for the extra $2000

Frank@Work

Thanks guys!

I will be on the lookout for a 951 LSD gearbox.

gt37vgt

pitty I'm so far I have one spare

seattle951

Would a 968 RS transmission be a better fit? They have longer gears. I saw one on e-bay sometime ago.

Also, I have a 968 LSD on my 320 RWHP 951. Around town there is significant improvement. However, at WOT, the gears are too close and some performance is lost. (Can't shift fast enough). The LS1 would make it even worse.

MPD47

Considering the $9k+ price tag last time I had someone look, enjoy.

chilibluepepper

Another possible option: Swap in a 951 R&P into your S2 transaxle. This gives you the same ratios as a 951 tranny 1st through 4th, but you end up with a taller 5th, which the V8 engine can put to good use. The S2 R&P is a very desirable item to the turbo guys, and can be easily sold.

Frank@Work

That was my idea at first until I spoke to a Porsche transmission "specialist". I like the gearing with the taller 5 (low MPG on the highway).
The "specialist" suggested a Turbo S transmission because it is stronger.
When I asked him to make my S2 transmission stronger he told me I would be better of buying the Turbo S transmission.

I prefer to use the S2 transmission. Let it rebuild, replace the R&P with the 951 R&P).

Will it hold? (I don't do clutch dump starts!)

daigo

Frank,
The 951S does have hardened gears and shaft, but so does the S2 transmission. You only need to change your R&P to achieve what you are looking for. You have a PM.

JPR

Frank

I have an LS1 and use the 968 6 speed. the 6th gear ratio gets solved by installing a .6 gear from the audi bins. this is sold by JH Motorsports. I works great and I would not substitute it for the 5 speed.

Thanks

Jpr

chilibluepepper

As Daigo mentioned, I don't believe there is a strength difference between the S2's AOT transmission, and the 951S's AOR transmission, the basic difference is in the R&P ratio, and the lack of cooler in most AOT's (except Swiss boxes according to the FSM).

With final drives taken into account, the S2 to 951 to 968 ratios at the wheels, compare as follows:

DFASTEST951

I was gonna speak but Mike took the words out of my mouth. 9+ for a turbo RS gearbox...used.

After all my reasearch. 968 box is slightly stronger.
951 Turbo S is the strongest 951 5 speed.
I still broke mine and now I can't find a taller ring and pinion for my six speed.
I now have found a taller ring and pinion for my 5 speed.
My 968 tranny and associated parts are being traded in on the taller r&p for the 5 speed.
Any power over 350whp would make a stock 968 gearbox one big pain in the ***.

Soon as the economy turns around, I may actually be able to fix and drive my car.

JPR

The taller ring and pinion for the 6 speed is available but we need to get a few (5) together to have it build to the ratio we pick, otherwise it is cost prohibitive for a one-of. In the mean time, the JH Motorsport 6th gear options allows you to cruise in 6 gear at 2.7K rpm at 80 and you can get it even lower with the other optional ratio, but it makes the gap from 5th too large.

Jpr

gt37vgt

How much for that .6 6th ?
I will consider being one of the the 5. I would possibly get them done cheaper here .I guess my preferences would be a rato that gives 2200 for 60 mph in normal 6th would be nice and perahaps first gear like a 951 or a shade taller