1slick88cat

Would a 16cc dish pistion with a 9.0:1 ratio be safe for a supercharger or is 8.5:1 better

fordboy5.0

it depends on how much boost your runing 8.5:1 would be better if you were running high boost to compensate for the lower compression, but in m&ff they did a 4.6l with 9.0:1 compression and was running 10lbs on it and it was fine i would suggest if your going to run any more than 10lbs to go with 8.5:1 pistons because your engine will start to detonate.

mjr46

I know more than 1 person running 12-14 lbs of boost on a stock 5.0 block with 9 to 1 and no detonation, it's all in the tune

67mustang302

Tune and blower type. Centrifugals can run more total boost than a screw which can run more boost than a roots, mainly because of how they operate. But generally the lower the compression the better, since all things being equal it lets you run more boost and make more power. But there are a lot of 9:1 engines that are EFI running over 10psi with intercooling on pump gas. Blow through carbs and intercooling can run upwards of 15psi or more on 9:1 without issue.

My view is if you're building for boost, you might as well shoot for 8:1 and run more boost, though a stock block would split long before you ever hit your boost limit on an 8:1 pump gas engine.

fordboy5.0

rather be safe than sorry