david fracolli

Hossram you forgot the 88 N/A pistons which are 10.2 to 1.

daniel951

Yes i am sure. Me and danno are both running NA pistons at this time. He said my pistons will be good to at least 20psi. At this i am hoping around 400+rwhp. Its hard to tell if my car has alot more lower end tq since i haven't been in many 951's. Maybe at the next get together someone will take me for a drive and see. i will be posting vids for all u to see. If u look at my pistons they looks way different then 951 pistons. i will post a pic soon as i get home since i am at work right now

pk951

The pistons in the na motor are made of cast light alloy-- not forged so at 20psi that is a lot of heat going into the cylinder, i wonder if those pistons can take the heat at 20psi will be interesting too see the out come running that kind of boost. Why would porsche put forged pistons in there turbos cars.

daniel951

We will see if i blow up

daniel951

here is a pic of my pistons and the best pic i can find of a 944 turbo pistons. You can tell by the top of the heads

hosrom_951

David: Depends on model/Engine number (yes they were higher CR in later models)

Daniel: Could you tell which which NA pistons your running from which engine code? That is seriously impressive BTW

Dark Lightning

Is that a question or a statement?

Duke

We have enough detonation problems as it is with these old 8v heads. I would not consider higher CR pistons for serious power. But, if all you want is a better low end then go for it.

Daniel your makes impressive HP but I don't think much of that has anything do to with your higher CR. That would show up as better low end but your engine has in fact quite little torque and steep powerband. And that's usually the results of a big turbocharger and small/low CR engine.

pk951

Daniel 951

What is you're piston skirt clearance with those na pistons?

daniel951

To tell u the truth i have no idea on any specs on the pistons or what else has been done by the PO.

944Willie

See that's the reason this network is so good. I did not know and I asked the question. I had very bad information on the 997. As far as the Supra's that CR may be more bragging than real. I really do appreicate the corrections. I had wrong or at least not entirely correct information. I was thinking that a 2 point CR increase when combined with 12-18 PSI boost would have to be very hard on the engine, but with the advance in materials and electronics mabey they were getting there.
Thanks to all who have added insight on this.

macnewma

Here is a good summation of compression/boost:

http://www.dune-buggy.com/turbo/enginebasics.htm

Read down where they explain "Why is low compression better for a Turbocharged Engine?"

Max