Using 964 RSR 3.8 Pistons and Cylinders with Stock Heads and Crank

[CBRacerX]

I've got an opportunity to exchange $$$ for 3.8 RSR (964 Vintage) Pistons and Cylinders. I am rebuilding my '90 964 engine for primary street use with the occasional track event - for now. Later in the life of the car it will become a dedicated track car. So my thoughts are to use 3.8RS Cams now, to pass emissions and then get the 3.8RSR cams going once the need to satify the Gov't passes. I ma using a Varioram intake and Euro DME, so getting the tuning done ala Steve Wong should not be too tough.

Another option on the table is increasing the intake valve size a bit while the engine is apart.

Any thoughts? Somebody done this with the stock 964 heads rods yet?

Chris

[Cookie Porsche]

Chris,

No problem. You can fit the 3.8 P/C set and use standard heads and rods.

Tom

[CBRacerX]

Great! What compression ratio would you expect with the 964 heads?

[Speedster94]

hallo chris
usually they are 12.3:1
harald

[CBRacerX]

The upgrade has begun..
http://forums.pelicanparts.com/911-engine-rebuilding-forum/267356-another-3-6-3-8-rebuild-thread.html#post2420655

[Cookie Porsche]

Good luck,

3.8's are good fun and reliable power. While doing the P/C upgrade rather slap a set of cams in - the 3.8 is crying for more air. You'll not regret it.

Tom

[CBRacerX]

What is the conventional wisdom on the pin offset issue? Some folks are suggesting that the pistons need to be machined to permit one side to be flipped over so that there is no issue with reaching TDC at the same point on each bank.