z92maroman

I am building an LT4 for my '92. Factory comp. rat.'s are @ 10.8 due to the better combustion chamber cooling of the reverse flow design. What do some of you LT1/4 afficianatos think I can get away with, c.r.-wise? I'm thinking 11:1 should be acceptable w/91 octane pump gas & maybe some octane booster. I will be running AFR 195cc LT4 heads, & the car is mostly for show-n-go, not really a daily driver. The cost of fuel is not really a concern...

TexasLT1

its not even worth it to up the compression ratio of you do nothing else. Why bother? leave it at the stock compression ratio and don't worry about it. going from 10.8 to 11.1 is going to net you about 5 hp.

z92maroman

Actually, I am going w/AFR LT4 heads, Eagle forged 383 kit, SRP pistons, 58mm tb, compcams 306 cam, rev kit....far from "nothing else"! Just trying to get comb. chmbr. volumes figured out so I can start ordering the goodies! Thanks for the reply.

TexasLT1

I meant there is no point to up the compression as far as performance goes if that was your reason for upping it. If its a mostly show car, I wouldn't really worry about it too much as long as you stay below about 11.5-12:1. You're definitely going to have a hot combo with the parts you listed. Just get stock C.R. or slightly lower pistons depending on the combustion chamber size for those heads.