They’re all factory 915 up to 87’. The solution is 930 or g50

The later year 930 gearboxes are not too difficult to find. It's the added cost of getting the bellhousing shortened. I'm not sure what that individual cost is though. $3000 is my ballpark guess. ??

I just pulled my motor/915 transmission out to stuff a 930 gearbox in it. I broke something in 3rd at the track this past August. My boost wasn't even at full (~360whp). Most of the 915 transmissions are 40 years old, and without a rebuild plus the added stress of a turbo it won't take long to break. I turboed mine in October of 2015. So it did last awhile. But like Ronnie said, I was one of those dainty drivers with the 915.

^^^

Just to add a little mumbojumbo to what Brandon and Kyle said above, the input shaft of the later 930 boxes also has to be modified, but while adding some expense, and general hassle (as Kyle mentioned), the mods are a straightforward procedure (no experimental voodoo involved :D) that certain shops can do.

Also, the Wevo parts help minimize flex and stress by keeping the components aligned, but of course, does not address the skinny gears themselves. So if a 915 is to be used, then engine torque should really be limited to well under 300 ft lbs by keeping boost pressure low. But that said, even with a torque bump to say, 250-270 ft lbs at about 5psi boost, that is enough of an increase in acceleration force to have someone accustomed to the torque of a n/a 3.2, etc., going "Ohhhhh shiiiiiiitttttt" for a while! :D


I've been working that bisch, Geronimo, for over a year now, to discard his n/a thoughts and grow a set of real, boosted ballz, but all my methods have failed so far (subliminal messages, hype, questioning his manhood, posted turbocharger gifs, and even an elaborate meme-post that I created, etc.)! There might not be much hope for that chowderhead! :D

A little off-topic here, but why Porsche used CIS on the Turbo model when they already had EFI (and a very good EFI at its time)?, The Motronic system is far more advanced and has a much better control and precision for both the fuel and spark for any turbo setup.

I think Todd can still supply the chip and fpr. If not, I'll likely have a chip/dme for sale shortly after my vems arrives.

Hard for me to say. I guess money for design when it was still working pretty good? When the 964 turbo cis ended in 92’ or whatever it was still the fast car. Not just for Porsche. It was still the benchmark for speed.

Todd Knighton (Protomotive) put a Phase 1 system together for me about a year ago; I installed it into my '87 3.4L. I supplied him my headers, AMF, and FPR; he sent back a complete headers-to-throttle body turbo system, with custom Motronic. The set-up was really great. (I have since added a full bay intercooler, but that's another story :)). Todd knows the Motronic system very well.

Happy New Year everyone!

To chime in, Todd at Protomotive still supplies the chip required for the 3.2 Carrera Turbo conversion. You can also get their Dual Rate Fuel Pressure Regulator if desired.

I have recently completed my 3.2 Carrera conversion to turbo although I am currently improving upon the piping system and tracking a boost leak. I intend to write a post about my project some time in the future.

It is worth mentioning that my car is a Euro 3.2 Carrera with 10.3:1 Compression Ratio!