Originally Posted by articfriends

We need more info-when you say the previous owner added blower pistons-were they the j/e's with reverse domes (turbo/blower dishes or "cups") or just flat tops? I used to run a 502,I blueprinted it and got rid of the factory j/e's with the mini domes and went to the flat tops,I ran 8-9 psi of boost with no problems on that motor at 900 ft above sea level. If you have true blower psitons (which is what I have now in my 540) your compression assuming you have typical 118 cc heads is around 8-1,with the aw504 innercooler or the even bigger one (don't know swhich one you have) I wouldn't hesitate to run 10 psi of boost on 93 octane,I'm running 12-13 psi on 93 but I have ceramic coated piston crowns,aluminum heads but I'm also running head studs,mls gaskets,extra hold down studs in the valley,dart big m 3 block. No signs of detonation,no knock events on the computer and it makes a TON of hp. I would go down 2 pulley sizes if it were me,example-your running a 4.25"-go to a 3.85". Make sure your belt is tight too first. Air density-at 4500 feet elevation your going to loose a ton of measured boost due to the thin air,Smitty