hey guys i was wondering how high can i got with compression on pump gas? is 10:1 too high?

 

What is the highest octane pump gas available in your particular area? Are we talking about 93 octane super?

 

I notice that you drive a WRX. Are you asking about a Subaru boxer motor build or an Evo?

 

for evo 8 lol wrx is my other car

 

I would only go 10:1 on E85

 

agreed,you can go 10:1,but you peak boost will be low enough that you will loose power overall over 9:1.if i was going to build an EVO motor that would only see pump gas,than i would probably even go down to 8-8.5:1

 

my car is a 10.5 CR..... It' more responsive outta boost and builds boost a tad quicker and makes a little more power. I mean u have to have a good tuner when u start making jam.

 

lol i love this jam talk lately and yes i would say 10.1 is a good place for a more responsive outta boost engine whats the rest of your setup going to be ?

 

on 93 oct id say 9:1

 

that good off throttle response isn't going to be worth the 2-3psi you lose overall.9:1 or less for pump gas.

 

Pump gas.... yuck lol, but a little lower CR is better for inconsistent pump gas, what turbo and setup?

 

I have been trying to read IP on this and my understanding is that for 1 point of cr (9:1vs10:1) you can gain 3% potential in HP gain. But you can loose boost. Every psi of boost is worth about 3.6% potential power. But with tuning it greatly reduces the danger for the higher cr

 

basically yes and for a full point down of SCR you will gain at least 2 psi which will be 7.5% increase in power.the 3% figure for overall power by increasing SCR a point may be a little low,it could be 3.5-4%,but still you have to figure out what point the loss in boost will start hurting your new found power from the in SCR.

again none of this really applies for E85 or C16.

also you could start stocking up on Torco fuel accelerator and turn all of your 93 pump into 100+octane if you really wanted a 10:1 CR.i think at 100octane you would be past the pointe of diminishing return on the increase from 9:1 to 10:1.

 

whats ok for someone who wants to run e85 10mo of the year maybe just not during winter? but has access to 93

 

10:1 will be fine,just have a back up tune for the 93.i think you need that anyway just to flush the system with 93 every once in a while.