671 compression ratio help

Guys,

I have a 383 sbc with all the goodies, need to know what will be a better compression ratio before i buy the heads. If i run a 65cc head i get 8.1, if i run a 75cc head i get 7.7.
Will have a 671 running between 12-15psi?

Cheers.

 

go with the 8:1

 

I would not go over 10 lbs of boost or your wrist pins will play hell

 

I'm running 8.25. 355 & it's built. 14 lbs. boost. You'll be fine

 

What he said.

 

??????????

 

+2 on 8:1

 

Either way, you probably wont get away with running pump gas at that boost level. I'm not completely sure how your octane ratings compare to ours, but I checked on wikipedia and it seems both high grades are pretty close, since you use a RON rating and we use AKI. If that's the case, I'd go with the larger chambers and maybe even an aluminum head so you can make as much boost as possible (10 lbs?) on the street with premium and it will be more enjoyable to drive. You're always just a pulley change and a tank of gas away from a bunch more power.

 

Thanks guys. The heads will be alluminium. I'll let you know what numbers it makes.
Cheers.

 

If you go lower compression it will work better on the shit we call gas. Change your pulleys put better fuel in the tank and go to the races. That's what I do. My 2 cents