I've been searching for a while now on how much you can safely bore and stroke a 5.3 and there seems to be a lot of controversy on this build. I already have the motor(out of a 1999 chevy truck) and have plans to use a blower or turbo. I want it to be dependable but still make big power, I dont want to worry about overheating or pushing the block past its limits. What ci. will I end up with? I am building a 1989 mustang notch with this motor. Any help would be greatly appreciated!

 

I bored my 5.3L out from 96.01mm to 99mm, so in a sense I have a 346ci 5.7L iron block "LS1/LS6". 99mm bore, 92mm crank, stock rods. I would not have the machine shop bore any further than the sonic test allows, because not all 5.3L's are the same. I have read about sponsors going to a 3.905" bore immediately with the 5.3L, but after having my block sonic tested they found 3.898" (stock bore) was best because my #2 and #6 cylinders were thinner than the others.

I will say though, I built my 5.7L to prove a few things. It would have been cheaper right off the bat for me to pick up a low miles 6.0L and build that instead. The machine work ended up over $1100 for everything, and the pistons were another $300 something just for OEM replacement LS1 pistons from Speed Pro. You can surely find a 6.0L for under $800.

 

Thanx for the info, sounds like I need to go 6.0.