Hondata

Hey all, I'm running an 07 Si with a Kraftwerks supercharger kit (1000 cc Grams injectors) which has been tuned. I'm adding an external fuel pressure regulator with a 1:1 manifold reference, tapping into the manifold obviously, and I understand that this changes differential fuel pressure across the injectors over stock in most situations.

Should I just use sqrt(P2/P1) to determine fuel percentage change where P1 is 54 PSI (stock, what FPR will be set to cold and open air reference) and P2 is P1 + manifold pressure? e.g., under 5 psi of boost should I multiply the 5 psi column by sqrt(59/54) = 1.045 (4.5% increase) and 5 psi vacuum by sqrt(49/54) = 0.953 (4.7% decrease)? If that's not the correct route to go, do you have any recommendations? I just don't want my fuel tables to be way out of whack right from the get go. Thanks!

You can adjust the fuel pressure as you outlined, but I'm guessing there is going to be some re-tuning needed. With 1000cc injectors the external PR is a little overkill.

I supposed I should have mentioned that the purpose of the external FPR was for running ethanol. It looks like those changes got me closer to target AFRs, but yes, definitely requires additional retuning.