Hopefully a quick question. I was looking at stroker pistons for a 383. They give a CR of 9.8:1 with an 030 over bore. How drastic of a change is that to the CR if I have an 060 over bore?

it would be around 9.92-1

A bigger piston surface area increases the CR? Ok now I really feel like a newb, I figured it would lessen the CR. graemlins/clonk.gif

Originally posted by 70 Elco Joe:
A bigger piston surface area increases the CR? Ok now I really feel like a newb, I figured it would lessen the CR. graemlins/clonk.gif =
Not the bigger surface area.
Static compression ratio is nothing more than the volume at BDC compared to the volume at TDC.
If you add 5 cubic inches to the engine you are squeezing that extra 5 inches into the same space at TDC.
More volume stuffed in the same space equals more static compression :D

Yep after I looked at that post and got over feeling like a dummy I found a post on DCR. After reading the article it make alot more sense. Guess if I want to run flat top 383 pistons on pump gas I'm definitely going to have to get 72cc chambers when I get my heads.

Thanks for the responses guys1 graemlins/thumbsup.gif