Ive been reading on this site that i can make my 4.8 a 5.7. I pretty much get the whole concept of them being the same block and everything and ive been looking for used 5.7 pistons and rods on ebay but having trouble finding them. When i go to look at some aftermarket ones im not sure if they're for a stock 5.7 bore. What is the right size of stock 5.7 pistons? And yes ive tried the search tool.

 

Bore size is 3.89-3.90. I think the rod length is different between the two engines so keep that in mind when looking for pistons.

 

just buy an LS1

 

go over on tech and place a want to buy add.
your looking for the LS1 crank, rods, and pistons.
many over on tech have rebuilt their motors with forged parts.

 

cheapest easiest route

 

sdpc has an Ls1 set of forged rings and pistons (no rods) for around $500

 

they give them away all the time . . . and they're flat tops !

 

I think you will need an LS1 crank and bore the stock block to a 3.905 (I believe that is the bore for most of the shelf LS1 pistons)

 

so stock LS1 crank, forged LS1 rods or 5.3 rods and boring the block out to 3.905 will make 4.8L into a 5.7L?

 

I'm pretty sure thats what I told you in your thread... But it's easiest to just start with a 5.3 short block (since you need the crank and rods anyway) and bore it to 3.905 and put the LS1 pistons in it