bigSS

Well, i'm lookin into getting some more horsepower N/A. Can't afford getting an S2 head, so I was wondering if I would gain anything if I was to buy a set of stock 5.3s, and have 'em milled 25 though or so?

BIG PD

if you mill it .015 i think that put you at 11.1 cr ratio. you don't want much mor thn that.

bigSS

Ok, why is that? Anyone else?

1stgenguy

11:1 is about the max for 93 octane any more compression and with 93 and your motor will start pinging. I would even watch out with 11:1 if you get a bad tank of gas your are screwed.

Vents

iTrader: (9)

screwed? how's that? plenty of guys push it far further than that on pump gas, myself being one of them, fireball another, have done .060 on 5.3L heads and made 12.5:1 work w/ pump gas. it all depends on how much you want to mess with it.

bigSS

Would there be any horsepower gains from milling some unported 5.3s?

Fireball

iTrader: (21)

I've gone .040 on mine...93 octane only but running a large cam to bleed off dynamic cyl pressure helps too

Vents

iTrader: (9)

bad idea. you at least want to have bigger valves put in. the stock intake valve in the 5.3's are very small. like 1.7-8" or somethin. the compression might net you 10-15 RW though.

offaxis

iTrader: (19)

Ive heard its as low as a 8-10 hp gain per point of compression raised. Hardly worth the time or expense.

98TAauto

iTrader: (2)

i just got 11:1 on my 5.3's mainly cause I see plenty people running that CR on 93. Besides I have edit so i can always bump the timing back a degree or so if there is any pinging

have you looked into TEA or AS heads?? you can get stage 1.5 or 2's for 1300-1700bucks give or take on GP's

those heads might dyno 10-15less than the 2400-2800 bucks heads, but oh well Ill just drop 15pounds off the car to make up for it LMAO