3.2 Pinging!

[KobaltBlau]

Originally posted by IROC
Andy - I bought this engine off of a local guy after he had rebuilt it and I'd have to say these are the Euro 3.2 pistons and not the Mahle sports. I'd have to verify that, though. To my knowledge, the CR wasn't measured during the rebuild. I've always heard that Mahles are notorious for resulting in a lower measured compression ratio than advertised.

Well, it's a small thing, but the euro 231hp pistons are claimed 10.3, where the mahle sports are normally claimed 10.5, though Andial doesn't list a 3.2 set for a 74.4 crank that I see.

Anyhow, the sports would be even more worrisome.

I agree that you might gain yourself some extra headroom by having Steve Wong re-work your chip, but there still may be pre-igntition or detonation going on that you can't hear. That said, 911 motors are easier to hear this stuff from than a typical water cooled motor.

[Carrera3.5L]

This is getting OT but Mahle Sports in 98mm (increase to 3.4L) for a 3.2L Carrera are rated at 10.3:1 for the carb/mfi dome and 9.8:1 for the Motronic dome. They are both available from the 2 Mahle distributors in North America which are Andial and SSF Auto Parts.

Ralph