I have a brand new 5.3L crate engine I plan to install a comp cam with 220/218 duration and 563-564 lift. It will also get new springs and push rods as needed. From what I've read new arp or katech rod bolts should be installed also. What I need to know is what power-boost levels are the stock pistons and rods capable of handleing. I have run my 120,000+ mile 4.8 at 12psi and it shows no signs of damage yet. Have I just been lucky or what. I run a very safe tune with next to 0 Kr and a/f stay between 11.1 to 11.6 at wot. I just don't want to install my new engine and blow it up.

 

I have ran up to 23psi but ran out of fuel at 20psi. I lowered my cr though, with the 6.0 heads..

 

While it's out you could bore it to 3.898" and drop some forged pistons in it and make it a 346 (5.7).

 

where did you get your 5.3 crate engine?...