3.4 ltr engine with 3.1 heads

[berniejayd]

Has anyone built a 3.4ltr engine (like in 1995), with the late 3.1 heads (2001)? If so, did you increase the chamber vol. and or the piston dish vol.? Nothing done the compression would appear to be more than 13:1.
Bernie

[geoffinbc]

Change the pistons. Factory, after market and custom pistons are available

[berniejayd]

I discussed pistons with a couple of makers and basically we're talking custom pistons. Nothing wrong but the price. This engine is popular but many makers of engine goodies are not making parts.. I know as I've spent time looking. I have already recessed an area in these pistons for clearence of the intake valve and I will just increase the dish volume from current 9 cc to 12. I was curious if anyone else had made modifications to make the stock parts work. I also have increased the camber volume to 31 cc. I'm looking for about 11.5:1, will check with the compression calculator (a very nice part of this web site).
Thank you "beterthanyou" for your sugestion.
Bernie

[geoffinbc]

Well if you use stock 3400 pistons from a FWD car you will get stock compression ratio with the .060 head gasket. Which is under 10:1. If you use 3.4L Camaro pistons with the 3100 heads and the .060 gasket you get 12.5:1 if I remember right.

[berniejayd]

3.4/3.1

If I had a stock 3.1 head with the normal 27cc vol and the stock Camaro 3.4 pistons (1995) and a head gasket .050 (I measured a well used stock gasket and it measured .050) my compression would be 13.1:1....to high.
If the head had a chamber vol of 30.5 and pistons had vol of 11.2cc with the .050 gasket and a deck of .012 (deck I have now) the ratio would be 11.58:1.
Yesterday I had too much time on my hands and I finished the pistons as above... if I did not make a calculation error all should be well.
Bernie

[geoffinbc]

I agree 13.1:1 is a little high. But it sounds like you got it all figured out. 11.5:1 should go good with a descent cam.