Have 500 hp on motor with forged pistons, rods, and girdled oil pan. Would a 175 or 200 shot be good for this setup or a little to much? Ran 125 shot on totaly stock engine for 2 years and didnt have a problem and would like to go up a little if engine sounds strong enough.
The only other variable is your compression ratio. With 9.0 or less, I'd say that you should be fine (assuming that you keep your RPMs to 5800 and less). What is your cam's overlap? Do you have headers and a free-flowing exhaust? Disclaimer: I am assuming you have AMPLE fuel delivery (a dedicated fuel system is best), a very safe tune, reliable components that you check regularly, run adequate octane, and a fuel-pressure shutoff switch. -Bob Cunningham
I shift at 5500 so the rps are below what you stated and i do have 1 7/8 headers and 3' exhaust, the cam is postons gs-113, compression on pistons were listd at 9.1 to 1, but dont know if or how much the heads or block is being milled to get a flat surface.
stock rods stock crank forged pistons no girdle with a 250 shot no problems 4 last 5yrs except for a blown head gasket
The girdled pan worries me more than a 250 shot. It's been said to have drain back issues unless you made "window" drain back provisions... I hit it with 200HP if it was mine.....Make sure you have a fuel safety switch wired in for the nitrous.:beers2:
I got the girdled oil pan a few weeks ago from poston and in the pan where the extra alluminum webbing is running across the oil pan for the preload bolts, there are spaces running down the oil pan for the oil to drain easier instead of having to go over the humps of extra metal of the girdle.
I ran a 125 powershot on my stock engine with no problems, just follow directions and make sure you have enough fuel.
