I am doing LS6 heads on the 5.3L block. There are different head gasket part numbers for different years of LS1 motors...I didn't think there was any difference
I was thinking of going with stock multi layer steel GM head gaskets. Is something better for the 10psi of boost that it will see? I think the stockers will be fine, but which ones to get with all of the different part numbers - I couldn't even find a '99 5.3L truck head gasket pt#?

 

I believe you have to use 5.7 gaskets on that application because to of the reduced diameter of the 5.3 bore. As far as what thickness to use, you got me. Since the new heads are already going to reduce you comp, I dont know how low you want to go. With the thickest gasket, you could just poor on more boost.

 

Does anyone know why there is a difference in part numbers for the early vs. later years of an LS1 head gasket? Are the gaskets really even different?

BigKID, I have heard that increasing head gasket thickness increases risk of blowing out the head gasket. I see your point though of lowering compresson to run even more boost. It is addictive

 

GM makes both a graphite head gasket and a MLS (multi layer steel) gasket for the LS1. I bet thats why you have two part numbers.

 

You will have to use the multi layer gaskets. The earlier graphite gaskets won't seal around one of the lower water passages on like 99 and up ls1 and all ls6 and 6.0 heads.

 

Thanks for the advice guys So later model Multi Layer Steel head gaskets it is.

 

When I put 5.7 heads on mine I used Fel Pro head gaskets for the 5.3.

 

Ryan
Where are you running you maff ?
Before the Blower ?
Or after the intercooler
I hope after the intercooler

 

Hey twobit why would you do that if the 5.7L has a 3mm larger bore? Doesn't the gasket overlap the bore some? Is it all working well?

 

I had someone install them for me and he suggested I use the 5.3 gaskets due to compression ratio (i wanted to keep it up as much as possible)etc. If you don't mind the compression ratio going down then I would use the 5.7 gaskets.
Ive driven the truck 1000 + miles and have had no issues.