Thread: 7.5 CR pistons?
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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269

8/1 is such a good fit for a street turbo. 7/1 is more of a race car set up. The 993TT ran 8/1, the 3.6 CIS turbo ran 7.5/1 and had a 3.8 optional P&C kit that was 8/1. I would not go over .8 bar boost and a bigger inter-cooler and or more effecent turbo (K27-7200) is a good idea with it.

If your cylinders are in good shape you can get a set of J&E turbo pistons in any configuration you wish for probably a bit over $1k. Might want to check with TurboKraft or EBS in Reno. Another option is a set of fined 3.2 cylinders bored to 3.4, re-plated, w J&E's. EBS can do that for you I hear. Then you can sell you set.

Another option is to send the rods out to be stretched about 1mm. With this they offset bush the small end. This should get you to 7.5/1 and you can keep your factory pistons.

It sounds like we should be able to get factory P&C's in custom builds. If so, that might be a best practices way to go.

SC cams w a low restriction muffler and setting the CO to about 3% also helps low end. Increasing ignition off idle by modifying the Pot's retard stop is also something to look into (Andial dist re-curve and mod).

Not an expert, just my two cents.
Old 12-07-2009, 08:21 AM
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