compression questions

[whitmanink]

soo im looking into how i want to go about this 3v build,,
im pondering making a higher compression,,
like in the 10s, or 11s

if i did this , could i still use a turbo after a bit , or would i need to stay around 9 compression to be safe?

also,, what would be the hp gain going from stock up?>

anyone make there compression go up and have feedback about it?

thanks guys ,,

 

[stkjock]

really depends on what fuel you're willing to use/pay for, a higher CR will certainly make more power, yes you could add a power adder at a lower boost level then you would with a lower CR. IIRC the CR in my engine is in the 9.6-9.8 area at 20 psi on E85

If you go E85 or a race fuel, you have more room to up the CR.

 

[1ohiostang]

When I redid my motor I bump the compression up a fuzz to 10.25. I'm only running 12 psi. I can tell you off boost the drivability is much better.

 

[Laga]

Your 3V has a stock CR of 9.8:1. The reason most manufacturers lower their static CR for boosted engines is to keep them on pump gas. They could make a car with an 11:1 CR, but as soon as they put a turbo on it, it would need E85 or race fuel. This would limit sales. I just had my 05 rebuilt and after everything was done wound up with a CR of 10.12:1. I was using E85 before the build, and intend to keep using it. The 10.12:1 CR also allows me to go back to 93 octane pump gas. If I go somewhere where E85 is not available, ( As of now, I have 4 stations within a 1.5 mile radius of my house that have E85) it takes a different tune, and I keep the SCT tuner with me. It has high and low ethanol content tunes, along with the 93 tune.
So, just like stkjock said, it depends on the fuel you want to run.
There are exceptions of course, we have a 2021 CR-V with a turbo that has a CR of 10.3:1 and it takes regular 87. But the engine is not designed for performance.