Hi guys. I’m have a hard time deciding which CR to get. I plan on sleeving the H22 block. I plan on street drive and race only in summer. Want to get 700+hp for race and a street tune of 450hp. Any suggestions on piston and bore size. I’ll run probably a pt6062 or pt6067 turbo.

 

Use a "Flat-Top" style piston... this should put your compression ratio around the 10:1 mark, give or take a few tenths.

 

Higher compression ratios yield a better throttle response and off boost power as well as quicker spool and lower rpm torque but are also more difficult to correctly tune due to the increased chance of pre-ignition. Typically if your running boost you wantt to stay in the 8-10:1 range, 700hp is alot so 10:1 or so is about as high as I would go, depends on how good your tuner is. I have heard of some people running 12:1 though and making 700hp too so idk.

 

The above mentioned is all true.
BUT, the decision also largely revolves around your choice of fuel.
At 10:1, you will be able to make 450hp on pump gas as long as you have a good setup, especially the manifold. 500 will be about the limit on pump gas.
700hp on the other hand, it doesn't matter what compression you run, you won't make that on pump gas. You'll need to run either some form of race gas, e85, or meth. And if using any of these fuels, higher compression is always better. So again, 10:1 is a good choice.

 

For strictly pump gas 10:1 is a good compromise. Personally I like 11-11.5:1 but as stated alternative fuels are helpful when going that high.