odd piston question

[Ben j]

wat would be better for a civic type R?

11.7:1

11.4:1

or

11.5:1

 

[Fred@BTM]

whats the std comp ratio???

 

[YoShImUrA]

Take into account that unless you use texco's 99RON gas u won't take advantage EVEN of 11:1
So if I were you, I'd pick the least compression, since the gas you are going to use isn't ready for that...
I repeat, not even TEXCOS finest! look, it goes this way: 9:1 compression goes with 95RON, 10:1 with 98 and 99 actually is for about 10,5:1...so don't bother with higher compression, as you'll only get higher stress on the engine and also, unless u use racing gas, it won't make the car faster...
Hope I was clear enough to understand, lol ...
cheers

 

[BenR]

The static CR really means very little when you consider it as a means to decide on performance and reliability. You have to know the dynamic CR's you will be running at the points of peak VE. If you never hit 100% VE then you will never hit the calculated static CR, if you do and go over it, then you will be running higher dynamics than you will statics (as in good NA and forced applications).

The K20A has a superb combustion chamber, and if you have the right piston you can get away with ridiculous static CR's. I would go with the highest because even if your running the std camshaft and the std inlet manifold (even the JDM version) you wont be pushing the boat out.

Just make sure you get it tuned properly.

 

[stan*]

Take into account that unless you use texco's 99RON gas u won't take advantage EVEN of 11:1
So if I were you, I'd pick the least compression, since the gas you are going to use isn't ready for that...
I repeat, not even TEXCOS finest! look, it goes this way: 9:1 compression goes with 95RON, 10:1 with 98 and 99 actually is for about 10,5:1...so don't bother with higher compression, as you'll only get higher stress on the engine and also, unless u use racing gas, it won't make the car faster...
Hope I was clear enough to understand, lol ...
cheers

Thats not exaxtly true mate.

as ben says, static Cr is meaningless pretty much. with your examples...if u had say 10:1 static Cr and a low duration cam profile, it could work out that your dynamic Cr is greater than a set-up with a static Cr of 11.5:1 and a higher duration cam profile. Thsi would mean that invariably the lower Cr would have the higher peak cylinder pressure, and so more likely to produce det.

If the combustion chamber is of a good design e.g. compact and promotes a quick/strong burn, then you can get away with quite a high static Cr....but there is lots more to consider.

Fred, what conclusion can you draw if i say the standard Cr is say 10.5:1?

 

[Fred@BTM]

Fred, what conclusion can you draw if i say the standard Cr is say 10.5:1?

i just wondering what they run fella