My friend is swapping in a B20VTEC setup consisting of a JDM 98 B20B block (P3F) and a USDM 98 GSR head. The question comes up, which octane does he have to use? According to C-speed Racing.com (http://www.c-speedracing.com/h...c.php), compression ratio will be at 9.2:1, whereas a stock B20B is at 8.8:1 and requires 87 octane. Would the addition of a GSR head require 91 octane or is compression ratio still low enough to run 87? For reference, stock B16's are at 10.2:1 or something like that, and require 91 octane.

Thanks for the help.

 

I would say 91 octane and up. But, someone else might prove me wrong so ye...

 

I was under the impression that compression ratio determined what octane is required and with it being at 9.2:1, would it be safe using 87?

 

87 guy above is correct. gas aint so bad in cali anymore. I got some for 2.25 the other day.

 

So 87 is safe?