<VV> Corvair Powered Porsche

jwcorvair at aol.com jwcorvair at aol.com
Thu Apr 19 10:14:25 EDT 2007


Because I have a Porsche 912 with a Corvair engine that I drive frequently, I thought that I would add my observations to the general discussion. My car uses a reverse rotation Corvair engine mated to a 1968 911 901 five speed transmission. My engine uses a Rochester four barrel on a center adapter for 110 heads. (Yeah, this is probably a bit more carb than needed for the 110 head, but that's the way it came.) Here is the issue with the Corvair engine mated to the 911 transaxel: The torque curve of the Corvair engine is not well suited to the gear ratios of the 911 transaxel. I can easily start in second gear. The gear ratios are so close, my best acceleration is when I make 1-3-5 shifts, which I can do without bogging the engine. I can have the gear box rebuilt with different ratios, but that is an expensive proposition (after all, it is a Porsche gear box). Also, the early 901 transaxel has one of the poorest shifting gear boxes that I have ever experience. And it is not only my gearbox. Every early 901 I have driven is so vague, it is quite easy to nick reverse when shifting from first to second. (The early 901 gear boxes have first to the left and back. Reverse is to the left and forward. This leaves second through fifth in the H pattern.)
 
The fellow I bought my Porvair from told me that if he had it to do all over, he would have used a Corvair four speed with the engine. He wanted to have turbo setup, but the turbo would not work well with the 901 gearing. (Even the original 930 Turbos had only a four speed gear box.)
 
I can see many advantages to using a Corvair gear box when building a 911/912/356 hybrid. The biggest advantage, in my opinion, is that you would have an engine and gear box designed for each other. The second advantage is that you would not need to build a reverse rotating engine. I have thought about using a Powerglide in such a conversion and adapting an early Tempest Powerglide gear selector to the Porsche. (We had a discussion on VV a couple of years ago about using a Tempest Powerglide selector in Corvairs.) I suspect the person that build the Powerglide Porsche adapted the Porsche shifter to a modified cable for the Powerglide. I have often thought that a properly built (that is, modified for performance) Powerglide could make a very good autocross transmission in a light car. Left foot braking comes to mind.
 
Just food for thought. Regards,
Joe White (62 Sedan [with Powerglide], 66 Porvair)
CORSA, RMC
________________________________________________________________________
AOL now offers free email to everyone.  Find out more about what's free from AOL at AOL.com.


More information about the VirtualVairs mailing list