dreambird

I was wondering if anybody new what the compression of a 5.3l truck motor would be if 4.8l pistons were installed in it?

99LS1Bird

as far as ive read it shouldnt change at all the only difference in the 4.8 and 5.3 short block is the crank(stroke length). i think the heads are different though the 4.8s should make a good bit more compression

dreambird

I have read before that the 4.8l engine has flat top pistons and the 5.3l has dished pistons but I have not seen how much it would go up with the 4.8l flat tops in the 5.3l with the stock 5.3l heads

batboy

iTrader: (6)

You are correct, the 4.8 piston is flattop and the 5.3 is dished. The truck guys often swap in 4.8 pistons into their 5.3 engines to raise the CR. I can't remember how much, but I think it was either a 1/4 or a 1/2 CR point. Check out the performance truck part of the forum, I know I've seen this over there.

dreambird

thanks alot for the info I am trying to decide if it would be better cost wise to put the 4.8l pistons in or have the block bored to run 5.7l pistons . I will check out the truck forum as you said thanks again!

5.3LJimmy

iTrader: (10)

Compression will be raised from 9.5 to 10.3:1. 5.3 and 4.8 both use the same heads.

dreambird

thanks alot for the great info!