Short block CR?? - Subaru WRX Forum
 
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post #1 of 3 Old 03-31-2015, 10:26 PM Thread Starter
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Short block CR??

RalliSpec Race Spec Shortblock

So i'm going to purchase this block from Rallispec.com but need a little help choosing CR. I don't know if i should choose the 8.2:1 or the 9.4:1. Ive already got the cosworth ported heads ( Cosworth CNC Ported Cylinder Head Set w/ 20007395 Cams Subaru STI 2008-2015 20010140 at RallySportDirect.com ) but don't know what i should get. I'm kinda new into the boosted seen. I plan on running the Perrin rotated GTX3582R. while tracking the car id like to use VP race fuels C-10 mixture. If anyone has suggestions or pointers id like to hear them.
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post #2 of 3 Old 04-01-2015, 04:20 PM
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I would think 9.4:1 would be stupid high for what you're trying to build. As psinuse though.

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post #3 of 3 Old 04-09-2015, 10:22 PM
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Quote:
Originally Posted by mosc View Post
I would think 9.4:1 would be stupid high for what you're trying to build. As psinuse though.
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Quote:
Originally Posted by Monavillen
RalliSpec Race Spec Shortblock

So i'm going to purchase this block from Rallispec.com but need a little help choosing CR. I don't know if i should choose the 8.2:1 or the 9.4:1. Ive already got the cosworth ported heads ( Cosworth CNC Ported Cylinder Head Set w/ 20007395 Cams Subaru STI 2008-2015 20010140 at RallySportDirect.com ) but don't know what i should get. I'm kinda new into the boosted seen. I plan on running the Perrin rotated GTX3582R. while tracking the car id like to use VP race fuels C-10 mixture. If anyone has suggestions or pointers id like to hear them.
Okay if your new to the scene, then I suggest going with something a bit more manageable....8.5:1 compression is as high as I would go. You can go higher and probably achieve a better power band, but longevity would not be your friend. Just take a stock STi motor with forged pistons in it and go from there. There are people making 600hp on a stock STi motor. Everything you have listed is simple to much for anything other than full on race car.

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