mdvaldosta

PI headed non-PI cars run about 10.2:1 compression. Alum headed engines can run about 1 full point compression more because the heads dissapate heat faster.

stonemonk9

im not arguin that im goin to go higher than that with out runnin 100+ fuel, that wuld be somthn i wuldnt want to do. so thats why ive asked can someone tell me wats the best way to make a powerful na motor? i read somthn on another forum about some guy bored and storked his 4.6 out to a 5.3. would that be worth it? anybody know of the gains?

roundman

check out this site and see what they have to offer
http://www.seanhylandmotorsports.com/
Sean is one of the first guys to heavily modify the 4.6L engines so he know all about what makes them tick!

Phirantes

I don't mean to bring in a newbie question but i'm just figuring out all this PI head stuff.... do some years of mustang come stock with the PI head? and what makes the PI head better?

stonemonk9

pi heads are on all 99+ mustangs, that with a few other things is bascially wat gave the jump up to 260hp

Bob99GTConv

Go here to see a good discussion on compression.

http://forums.club4ag.com/topic.asp?...TOPIC_ID=35957