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bosman bosman is offline
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Join Date: Sep 2007
Posts: 52
need advice on pistons/cylinders

I am backdating a '79 930 to a longhood look, and to avoid needing a spoiler on the enginelid, I am installing a 3.0 non-intercooled 930 engine. The engine was bought from another boardmember and supposedly in good condition and resealed. Some clumsy details on the engine (two types of chain tensioners, timing way off, etcetera) made me doubt the build quality, so I had my local engine builder (40+ yr Porsche mechanic) take the engine apart. That turned out to be a good idea, many things were wrong. Disappointment... However, that's not the point of this thread.
Not surprisingly, there is some wear on the pistons and cylinders. Nothing really serious, they could be re-used. But we're getting to the familiar "now we're at it" point, and considering to do a little upgrade.
Things we'll be doing for sure are:
- install 964 camshafts
- install RarlyL8 headers, central outlet muffler, 934 style wastegate pipe
- install K27S turbocharger

The car will be used for fast street / DE / trackdays, and driveability (i.e. low end torque) is a high priority.

Now my question; should I consider replacing the pistons to raise the compression? If so, how much? 7.5:1 ? What type/brand pistons should I use?
Or take it even one step further and replace the cylinders as well?

Again, the goal is to build a fast and fun car, but not break the bank...

Anybody have any experience with this?
Any thoughts or advice is much appreciated!

Old 07-12-2011, 05:28 AM
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