Ok guys, got another question for ya. So I've heard you can bore the 5.3 out to a 5.7 and everything be ok. Can you do the same with the 4.8 block? The 4.8 and 5.3 have the same bore so I would assume it's the same block just a different crank (3.27 stroke). If this is the case you should be able to swap in a 5.7 or 5.3 or what have you crankshaft correct? I might even leave the 4.8 crank and just go with bigger pistons for a quick/high revving 312ci FI motor. Just some ideas I'm thrwoing around. The smaller displacment should make more HP on the turbo up top but loses low end torque from my calculations. Should be maxxing out around 6500rpm in the HP.

 

sounds like a really hot combo..... might not be too good for a heavy truck, but in a f or y body would probably be a killer setup.

how close is this idea to being attempted? or are you just thinking out loud?

 

i remember something on here saying the 4.8 and 5.3 block are the same and that if you look on the back of to block it says. 4.8/5.3 block.

 

I like that short stroke idea!

 

You can also take it out to a 3.905" bore and stick a 4" crank in it. You'd have a small bore 383.

The short stroke high reving idea is cool, but if you have the opportunity, put a longer stroke in it. With how cheap LS1/5.3/6.0 cranks are these days you'd be foolish to stick with a 3.27" crank in a truck. Trust me I know.

 

Piston speed with the 3.622" stroke is not too bad. I'd go with it. But why not use your crank and the 4.8 rods too.

Some forged aftermarket pistons and good rod bolts will take you far.

 

the 5.3 rotating assembly would make that into a 5.3, so yes, you could bore your block to whatever makes a 5.3 a 5.7, and use a crank even larger than that of the 5.3 and w/ a little clearancing could get a lot more cubes out of it. I'd like to see a buildup like that. From my theories in my head i believe that the more stroke, the more torque. correct me if im wrong.

 

I agree, these trucks are to heavy to give up the low end torque you would get with a longer stroke.

 

I think you would still need custom pistons to keep the 4.8 crank. Correct me if I am wrong, but I think the 4.8 has a different length rod and the different location of the wrist pin on the piston. So if you bored to 5.7 and bought cheap forged pistons the rods would be wrong.?

 

Not if the rods and stroke were matched. I believe the compression height is like 1.31" or something like that. 9.24" dech height minus 6.275" rods minus half the stroke (3.26/2)1.63 equals: 1.335 which would put the piston .0025 in the hole at zero deck.
could use these pistons:http://www.sdpc2000.com/catalog/4135...e-6125-Rod.htm