One of my friend want to build a Time attack car in EU. so he asked me what is the good Compression ration for a 2 liter 4g63 on that level and wich turbo would be a good choice?
Any technincal info would help.
He really looking for the compresiion ratio for a 2 liter engine and maybe the valve size , the turbo size would help too.

Thanks for your times guys.

 

What fuel is it going to run on? That determines alot of the answer to your question. The next is this 600whp or 600 at the flywheel? A GT35 or similar size will meet both of those requirements and then some.

 

The higher the compression ratio the more power you can make with less boost (Mazdaspeed 6 and 3 for example had a 10:1, roughly, compression ratio, but is only able to do so due to its DISI ignition system). So rule of thumb is to drop the compression ratio. Not sure with the 4G63, but some of the high HP SR20DET's are running around a 7.5 to 8.0:1 Compression ratio.

 

he will run on race gas, sorry i forgot.Yes the hp is what he was telling me at a crank. So i guess that is why he said between 600-700 hp. /funny even we have dyno's there too they still talking about crank hp... /
thank you guys , i greatly appropiate your help, here.

 

this would be the way to go for road racing but it is a 2.3.
http://www.amsperformance.com/store/...oducts_id=1639

 

the rules are only 2.0 l , period.

 

that's what i thought. i wonder if they can do a rr treatment on a 2.0?

 

they racing along time ago in the rally.
But they got a bug from somebody... / / for road race. So they will start doing it this year. They just need a set up for it. and since its different ball game , need some help for starters. It is makes easyer.
I just talk to them so will be a 288's brian cover cams ,35 R and race gas for sure.
But we still need to find out the close to optimal Compression ratio for that set up. And maybe some suggestion for the valve's.
Thanks.

 

running on race gas, I'd run higher compression, since you get better off boost response, somewhat less lag, etc. There are other benefits, but I'm over simplifying.

I would consider 9:1 or even 10:1 depending on the fuel you're going to run.

Hell, stock compression is what, 8.8:1, and people make plenty of power on that.

 

Id stick with 9:1

 

thanks guys

 

I say go with 10:1

 

I support 10:1, can make your power running less boost.

 

9.5:1 + GT35R, less boost, but higher revs, however:the higher rpm, the harder it is on the engine, rings will need to be replaced more often.

 

I run 9.4:1 on a 2.2 stroker with a GT35R, producing 621Bhp on 97Oct with quite aggressive timing, but I also spent a lot of time on the combustion chambers, reprofiling the chamber and modifying the squish to reduce chance of detonation. Comp ratio isn't always the whole story!