02bluess

iTrader: (18)

Anyone out there know how much compression 5.3L heads milled .015 would make on an LS1?? I'm thinking ~ 11.4:1??

I've got LS1Edit, so I'm thinking I should be able to pull some timing and run that compression on 93octane. Thoughts??

TIA

Fireball

iTrader: (21)

FWIW, I have .040 off my 5.3L heads and run fine on 93 octane

02bluess

iTrader: (18)

Cool!!! That's what I wanted to hear

Sears

You should be ok on 93 with the proper tuning.

Justin

TEA Brent

The compression ratio on a 5.3 milled .015 is around 11.0:1

Bad02WS6

Hey Fireball. Aprox. What is your CR with .040 off?

444rwhp , What are you calling a small cam?

Thanks!!

LARRY01Z28

iTrader: (28)

Im getting .020 shaved on 5.3L heads and i was told it will be 11.2 CR

Fireball

iTrader: (21)

Jason99TA told me its probably ~11.8:1. I haven't CC'ed the combustion chambers to be 100% sure though. Well my cam is small by today's standards...was big at one time

232/232 .574/.574 112

Tin Indian

I may be mis-informed, but I can't see how you guys expect to run todays pump gas with 11.2 to 1 and above compression ratio.

With my TEA 5.3L heads (milled a mere .003"), my CR is 10.8 to 1 (63cc chambers). At that, 92-93 octane pump gas is ok, but pushing it as far as knock retard is concerned.

Sure, you can take some timing out of it with Edit, but there comes a point where there is nothing gained by increasing CR, while pulling timing out of the motor.

Just my opinion,
Ron,

Bad02WS6

Hehehe!! Thats still a big phucker in my world!
You've got to be running valve reliefs in the piston's..Yea???
How did you get the cam in with .040 off the heads?

Thanks alot!!!

Vents

iTrader: (9)

"I may be mis-informed, but I can't see how you guys expect to run todays pump gas with 11.2 to 1 and above compression ratio. "

why not? i know a few LT1 guys that run at 12.2:1 on 93. i think this general rule or, "myth" as i like to call it, has more to do with your specific application rather than anyone else's opinion. im not bashing, im just saying that if you are good enough to get away with it... go for it.

Fireball

iTrader: (21)

I have my total timing cut to 26 degrees for street use, but I've dynoed and saw absolutely no horsepower gains going from 26 to 32 degrees (and everything in between) when I dynoed on good gas.

I pulled 440+ RWHP on 26 degrees.

No KR at all on 93 octane with .040 milled off my 5.3L heads. Then again my dynamic CR is alot lower running a 230+ cam

Fireball

iTrader: (21)

I had to cut .055 off the tops of the pistons to get .070 PV clearance on teh intakes. Exhausts has plenty of clearance