Way2Fast

iTrader: (1)

OK, title says it all really. Was thinking of going with cncd 5.3 heads milled to get 11 to 1. I see others running a little bit more and was wondering how high you can go without having to run better fuel?

wildcamaro

iTrader: (15)

I've seen a bunch of people run 11.5 on 93 no problem...

Darkman

iTrader: (2)

The answer also depends on the dynamic compression ratio which is a function of what cam is used.

https://ls1tech.com/forums/generatio...93-octane.html

https://ls1tech.com/forums/advanced-...ion-ratio.html

nastychevelle

iTrader: (7)

the answer depends on alot more than just static compression ratio. You could have a stock headed 302 and run 13:1 on pump gas because it moves no air!

Way2Fast

iTrader: (1)

Fair enough with the dcr being more important. So when deciding with the overall setup, I will have to consider that aspect of the can just as much as the rpm range I would like to peak at.

I just see that the cars that seem to be a little freakish on the power for the combination, generally are taking advantage of higher comp.

garygnu

bigger duration cams bleed off pressure causing a lower DCR,so you need higher compression pistons to raise it .

Darkman

iTrader: (2)

You don't necessarily have to select a cam based on the DCR. You can select the cam based the usual variables - how the car is to used, weight, heads, etc. and then choose how much to mill the heads based on the DCR and octane restriction. Simply put, with larger cams (duration) you can get away with a higher static compression ratio, and with smaller cams the maximum static compression ratio is lower. And, of course, there can be the issue of flycutting.