thinking about putting a ITR Head on my B18C1 , i have heard the compression ratio will be lower, does anyone know what it will be(with stock GSR pistons)? also is there any other special needs besides using the ITR manifold, TB and ECU ?

 

9.7-9.8:1

make sure you have all your wiring, new head gasket, new head bolts. might as well change the timing belt too.

 

9.6:1

 

i thought the CR would be higher

 

I have always heard that the putting on a B18C5 head will lower compression because it has a larger combustion chamber, or something to that effect. I have always heard it lowers compression about .3 points. A good way to get around that is to get a mugen or spoon head gasket to compensate for the lowered compression. You will then be roughly back to the stock 10.0:1. HTH.

 

The reason you posted is correct. A Mugen HG wont increase the comp by .4 on a GS-R motor though, it will do so on a JDM ITR motor.. which means JDM ITR pistons and ITR head. You're looking at ~.3 increase on a GS-R IIRC.

 

ok, so the best way to maximize performance is to get some ITR pistons too or will the slight decrease in the CR not affect the overall performance that much?

 

im about to put a b16 head on my gsr block. pseudotype r baby!

 

your CR will drop
the cams will not be at TDC anymore. will need adj cam gears.

 

anyone know performance numbers for the head on with or without the mugen head gasket on stock GSR block and pistons?