I understand the basic differences but i dont see many people use a 8.5 CR would that be better for a turbo car? i know u would lose a little bit of TQ by doing a 8.5..

my question is, Why dont people a 8.5 CR?

 

thats outdated old school thinking. 9.5:1 is about the minimum people are running in new builds.

 

why and how is it old school thinking?

 

lower compression was needed on many turbo's because the engines were far more knock prone and the turbo's werent as efficient. many guys run 10:1 or higher on pump gas and a lot of boost with no issues. power doesnt really change, but driveability and bottom-midrange power is much better.

 

Whos running over 10:1 on pump????

 

A lot of guys. English racing seems to have a few (blkcarbonevo), buschur has some, etc.

 

mellon tuning evo is on pump gas on a 10:1 motor

 

I thought of you too while digging this up.

https://www.evolutionm.net/forums/ev...rod-build.html

 

i dont understand.. on a gas 8.5:1 i would think be better bec u can run more boost? but on E85 that would be a different story id say go 10:1

and anyways arnt 8.5:1 to 10:1 spool up and mid-rid power to the point were u wouldnt even notice?

 

The tuning capabilities these days make low compression motors useless.


-Em

 

so STM, English Racing , and Mellon run 10:1 motors on PUMP GAS?!

 

You bet!

 

Your logic is sound. It's just that one has to be willing to push things hard enough to take advantage of a lower compression ratio, and few do.

 

I said over 10:1 as you said people are runing over 10:1 on pump.

 

im not sure what you are getting at and im not going to search and post them all but some are even 10.5:1. 10:1 works great on 93oct but if you are stuck with 91oct its best to stick to 9:1-9.5:1.