The 1988 GTA has a L98 with 9.5:1 compression. Now, I'm buying some performance iron heads, and was told that going with 64cc chambers will up my compression to near 10.5:1 with will keep me from running 93 octane.

Is there anyone here running 10.5:1 compression on iron heads without needing higher octane fuel than 93?

Thanks

 

What fool told you that?

The stock heads are 64cc. If you go with a 64cc head, the compression wont change at all.

 

Your stock L98 chambers are 64cc as well. Your CR will not change with those heads unless you change your pistons. Don't be confused with 305 heads that have 58cc chambers.

 

Thanks everyone. That's what I needed to know. I'm really debating on the pro topline aluminum, because it's only $200 more than the iron ones.