Hey-

I have a quick question regarding B20s. I have the JDM B20b high compression motor which should be 9.6-1 compression. I found a good deal on a P8R B20 head so I want to know if putting the p8r head on will change my compression ratio? If so, do you know what it will be? If it drops it at all I may look into getting the head milled at the machine shop to compensate for the loss. Thanks guys

 

You could PM Irev210 or look for his B20 thread he made about the differences. I would imagine that if you switch heads that the CR would not change as the only difference I recall is that the Z had PHK pistons while the B did not.

If the head casting code is the same on both heads, I would assume that they are the same and CR would not change, but thats just me.

 

the P8R head has a 47cc combustion chamber... The B20 should be 45cc. You will lose a bit of compression, but IDK how much exactly. I would guess abuot 2-3 tenths.

You could deck the P8R head and maybe bring your CR back to like it was.

 

Awesome info. Thank you. What HG (OEM only) should I run with that setup? P8r, b20b hi comp, or are they the same?

 

something w/ 84mm bore... should be any b20

 

That works, I would think a b20z OEM HG will be one of the cheaper and easier ones to buy.