I'm thinking about swapping my 5.3 pistons for the 4.8 pistons. Will this raise my HP and compression? Since the 4.8s have a flat surface and the 5.3s are dished.
Thanks in advance

 

What year is your engine? all 07 and up are flat top from the factory, at lease the ones that I have take apart have been.

The dish is the old 5.3 pistons are so small I really dont think you could even feel the difference.

 

it's an 04 5.3.

 

It will probly bum p up your compression alittle and you'll probly get alittle decent gain on the low end but it would it be worth all that trouble just to do a piston swap? The ideal thing would be to save up some coin and do the pistons, cam and heads all in one go and swap the bearings while your in there for alittle insurance. Atleast thats what i would do.

 

If I was going to swap pistons I'd also bore the block 20 over....or just find a 5.7 or 6.0

 

I was thinking of boring it over, but haven't heard to much on the subject.
thanks.

 

My 5.3 has this exact thing done... you will increase from roughly 9.49:1 to 10.3:1 so its a healthy jump.. plus the 4.8 pistons are thicker and theoretically take more abuse.

 

I'll be doing this to my 5.3 this winter, if I ever have time.

 

So you've swapped the 4.8s in for the 5.3s.! Good are there any other mods you had done? How much horses do you think you've improved? The L33 has the 4.8s and it was a about a 15hp increase from the 5.3, but it's an Gen IV not a Gen III.
Thanks for your input.

 

L33 was a Gen III, but it had the 243/799 heads for a SCR 9.9:1. Some of the HP gain can be attributed to the better flowing heads heads.

I have seen 15-20 hp increase for a 1 point increase in CR given by other guys on the site. Just for clarity, that would be going from 9.0:1 to 10.0:1.