88 vert

ok i have S/C my 88 vert,I have the 550cc injectors,Apexi s-afc,Walboro fuel pump,and cartech FPR to control the fuel,im going to be starting up the car tommorow and adjusting the fuel pressure and try and get the air/fuel ratio the best i can until i can get it to a dyno,the cartech directions are/Example:6 psi boost is a pressure ratio of 1.41.With a stock fuel pressure of 36 at zero boost,than: Needed fuel pressure = (PR squaredx36)+boost=(1.41 squaredx36)=6=77.5 psi. The way i have figured this up is .235 squared for every pound of boost(right)?Which my car (88 vert) stock fuel pressure is 34.1-39.8 stock so i could use 36 as a rough figure to set the pressure(right)?So what should be my fuel pressures 1psi.-9psi.?I have been trying to figure this out and my brain is fried so if anyone has installed a FPR or can figure out what my pressures are supposed to be,i would appreciate it alot,Thanks,Dave

BlackRx7

What? huh, mujaboja? okay you seem to know pretty much but I have no Idea how to help you, this is a bump, just wanna clarify something, so if you get a Walbro and keep the stock FPR then your not flowing any more than stock flows through the fuel injectors? then why do all these guys with TIIs upgrade to wablro to help prevent detenation, with out having bigger injectors or a fuel controller this is worthless, right?

scathcart

B/c if your fuel pump cannot flow enough fuel to keep the rails at its pressure, the injectors don;t fire in as much fuel.

An upgraded pump prevents detonation not by adding more fuel to the engine, but making sure the existing injectors have enough fuel to "feed" from.

88 vert... I'll try to look into your answer a bit later. I am hungry. (your FPR is an axample of a common FMU supplied with centrifugal superchargers. I know some in this area.)

BlackRx7

aight that makes sense.

88 vert

please somebody help!!!!! i woulda had it running today but it snowing like blizzard...so i will have to wait till i get off work again to work on it,meanwhile im racking my brain trying to figure out this einstein of a formula..

scathcart

I agree with your formula. Might even be on the lean side... the stock FPR tends to get closer to 40 psi at zero boost.

Regardless, this will give you a decent enough baseline setting for STOCK injectors. You should be turning down the duty cycles slightly on the low end with your S-AFC until you actually get on the dyno.

I wouldn't fret too much over the formula... this is, after all, why you have an S-AFC. You're not running an EEC-IV here .