I am thinking about throwing a set of 4.8 flat top pistons in my 5.3 and milling my heads .20. Anyone know what my compression ratio would be? I think the higher compression ratio could help with sticking a good size cam in but thats another story. I know the idea of tossing 4.8 pistons in a 5.3 has been scattered among members but has anyone actually tried doing it yet? If so please let me know if this is a stupid idea or not. And no I dont want to get a 6.0.

 

Thank you for making taht point... everyone seems so hung up on the 6.0 they cant see past their own nose..... its like when people swore by only a small block 5.7 and you were shunned for fixing up a 5.0.... yet all the pieces were the same and you still made really good power with less displacement....

I dunno i guess its the ego stoking needed by the big cubes

 

I think you would have problems.

the 4.8 is (i think) like a 10.9:1 and the 5.3 is very close to that if not equal. Putting flat top pistons in would cause issues with compression and possibly clearance issues since the stroke is also diffrent. The 4.8 pistons protrude out of the cylindar walss a little and i dont think the 5.3 does. I think they are setup that way becasue of the stroke diffrences.

then adding taking that much from the heads would make it even more of a difficulty.

Someone correct me if i am wrong.

 

the compression ratio on the 5.3 is 9.5 to 1

are the rods the same length in both engines?

Maybe if I just did the piston swap and no head milling I could get away with P/V clearance issues.

 

no i do not think the push rods are the same length.

I would check though i dont even think just the pistons will work with the 5.3 strock.

 

see thats the thing that im not sure about...i need to be able to look at the pistons side by side...if they are identical other than flat and dished then there will be no problem

only thing i show as different is the 4.8 piston has a 1.324 CD and a 0.9452 pin diameter and the 5.3 piston has a 1.325 CD and a 0.9451 pin diameter. I would think that would be a miniscule thing. So you would have to use 4.8 pins to match exactly but are the pins at the same height on the piston? The rings on both are the same because they are the same size bore so there wouldnt be a problem there. Main thing I need to find out is exact height of each piston and where the pins are located.

 

Same Block.... Same Rods.... Diff Pistons And Crank

 

the only problem im seeing is depending on what year you go with it couls be floating pin, or pressed.

 

well i have a 99 5.3 so is mine floating or pressed? and then what year 4.8 piston would I need to get to match it up?

 

01slowz71 made a valid point in your other post... taht by the time you get the 4.8 pistons (stock) you can get flat top 5.3 forged pistons for fairly comporable price... and they would be more durable than the 4.8 piston