Stroke length question

ripper · Jun 27, 2007

Does anyone know what the stock piston stroke length is on a PI motor? My motor was bored .020 over and the cams are def not stock which we thought they were. .535/.535. Stock i think is .505. Im not complaianing but i need to know what is going on here. The guy that built my motor is on vacation and i cant get info untill he returns. I did some research and came up with a stock PI stroke of 3.552. Is that right? Mine is 3.554

. I dunno if this is because of the oversize bore or if he was adding stroke to the motor. My compression is 9.1:1. We are tunning thursday and i want to be able to know exactly whats going on.

Sorry if i sound like a idjit here but im not even close to a mechanic LOL.

firstonraceday · Jun 27, 2007

stock stroke on 4.6s is 3.543

ripper · Jun 27, 2007

Hmmmmmmm now im confused as heck LOL. Does that mean i have a stroked motor?

DropTopPony · Jun 27, 2007

no, a stroked 4.6 is more like 3.75...yours is stock

Paul · Jun 27, 2007

Agreed. Given the very nominal difference (a few thousandths) in stroke, I would say you have a stock stroke motor. Stroker crankshafts typically have more significant differences.

For example, a 351W uses a 3.500" stroke, but my motor has a 4.100" stroke. That, combined with an additional .040" overbore gains me an extra 71 cubic inches.