..........of B18A, B18C1 and B18C5 head.

Lets say I put GSR pistons (10.1:1) in a type-R engine. That will give me a cr of 9.6:1 in the R, cause the ITR head have a larger combustion camber. But how does this effect when putting some B18A pistons in an R block. Has the B18A head the smallest combustion camber, then comes the GSR and then the type-R head?

I like to put a JE piston for the B18A of 10.5:1 cr into a ITR engine. What REAL cr do I have now?

 

B16/ITR is 42.7cc
B18C is 41.6cc
B18A/B is 45.0cc

Using a GENERAL rule of thumb, where every .275cc reduced from the chamber yields approximately .1 higher compression.. an LS motor w/ a 42.7cc chamber will be 10.036:1
So if the pistons start off as 10.5:1, you'll be about 11.3:1 in your motor.

But keep in mind the LS has smaller valve reliefs. This can create some clearance problems. If the pistons are aftermarket forged, you'll probably be alright with clearance, tho.

 

I would chose JE pistons. When I take JE for a B18A, like the 8.5:1 pistons, do you think I´m okay with the valve clearence?


[Modified by austrian ITR, 10:50 AM 1/14/2002]