JDM B20b with p8r
 

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

Re: JDM B20b with p8r
 

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.

Re: JDM B20b with p8r
 

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.

Re: JDM B20b with p8r
 

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

Re: JDM B20b with p8r
 

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

Re: JDM B20b with p8r
 

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