hi!

Thats my first post in the Civic Forum since I am registered here on h-t I think

Well, a customer of mine needs to get out a c/r ration about 12 - 12.5:1. How to do that? He has to stay with 1.6i - cause of the competition class he race.

All I find a JEs, etc with max 11:1 c/r.

It seems the P30 b16b pistons with about 11.5:1 is the highest I can find.

Anyone knows the trick how to do it?

thanks

 

Well, your only option is to skim the head. This results in a combustion chamber with a smaller volume, thus increasing c.r. A good engine machine shop will advise on how much to skim off to get your desired figure (plus making sure you won't end up with a piston / valve interface - very expensive damage !!)

 

p30 is the jdm b16a piston. with the stock head gasket and a stock head(no shaving) you'll have 10.4:1 compression.
if you want 12-12.5:1 you'll need aftermarket pistons, and possibly an aftermarket headgasket. raising the compression from 10.4:1-12.5:1 cannot be done simply by shaving the head.

 

flat valves