Pelican Parts Forums - Increasing CR on a 3.2...how big of a difference will it make?

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- - Increasing CR on a 3.2...how big of a difference will it make? (http://forums.pelicanparts.com/porsche-911-technical-forum/252565-increasing-cr-3-2-how-big-difference-will-make.html)

Quote:

Originally posted by masraum
Hmm, the US 3.2L cars were 9.5:1, I think and had 217hp, and the Euro spec cars had 10.3:1 and had 231hp, so and increase of .8 gave 14hp.

The vast majority of the hp came from changes in the exhaust set-up, not the compression ratio. A Euro and and American car will dyno very close to one another with straight headers and an identical exhaust.

Quote:

Originally posted by cnielsen
I spoke with John at Engine Builders Supply yesterday and I think I am going to go with the most bang for the buck option and not get too crazy here. He recommended going with a 9.5:1 JE piston so we don't have to modify the Mahle cylinders. Add GE60 cams and then save weight with a lightweight clutch and valve springs.

This should be a good choice, but you will want weber 46s. I would do the ARP rod bolts too if you are doing GE60 cams, because with those I think you will want to run it to 7000 at least, not sure the stock 3.2 rod bolts will love that. I think a Mod-S or GE40 would bring the powerband down a little.