If you do not rattle or lean out the engine - at 8 psi your fine with cast pistons/rods.

Either one can spell a fast end to an engine.

I ran 9 PSI on a 10:1 vortec 4200 without any issues BUT I ran efi with timing control so I could retard the timing under boost.

I did rattle it a bit until I got the timing dialed back enough.

Last edited by efi-diy; 06/24/10 09:26 PM.
51 GMC 4.2 turbo
Can't solved today's problems using the same technology/thinking that created them