J.nguyen

well i was wondering why my tuner told me i would not need a FPR or gauge if i were to get tuned with my 550cc injecs on my stock LS. wondering why because my stock FPR 36psi is good enough already? juss wondering b/c i was thinkin about installin my FPR and buy a gauge but dunno if i really need it??

here is my air/fuel ratio


Modified by Jesse. at 11:30 AM 9/8/2006

drintegra

increasing the fuel pressure a tthe regulator increases the amount of power the injectors pull as the pressure is increased. Example if your injectors start running at like 95% at your current setup, you would just need to increase your fuel pressure to like 50psi and it would reduce the overall percentage to like 80 or 75%. I know the explanation is not great but this is the basic. You would def need a retune after this as you will be richer through out your power band and this was just an EXAMPLE OF THE THEORY.

dpetro1

i dont see why you would need a fpr with that setup. i could understand if the injectors were maxing out but 550's are not close to maxing out at your power level.

what fuel pump are you using?

J.nguyen

Walbro 255lph Fuel Pump

so i dont need to intsall my fpr and gauge? no need?

dont understand why my friedn who had a GSR tuned on crome with 550cc injecs near same setup as me did use a FPR and gauge and tuner used it to tune his car. but i didnt need one says my tuner ?

Jim Truett

You certainly don't need any more than 36 psi pressure with 550cc injectors at your power level. An adjustable fpr and gauge would be a waste of money for you. Is the GSR simply making more power? Were there other issues with fuel delivery that the tuner had to compensate for?

J.nguyen

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jim Truett &raquo;</TD></TR><TR><TD CLASS="quote">You certainly don't need any more than 36 psi pressure with 550cc injectors at your power level. An adjustable fpr and gauge would be a waste of money for you. Is the GSR simply making more power? Were there other issues with fuel delivery that the tuner had to compensate for?</TD></TR></TABLE>

oic. yeah gsr was making more power like around 300+ at 9 psi?

Jim Truett

At 300 whp and 45 psi of fuel pressure the duty cycle of the 550cc injectors would be right around 80%, the theoretical maximum safe level. The tuner probably raised the rail presure to 50 or so psi to keep it safe.

importdude2000

with ur stock fuel pressure level+550cc
injector duty=low so it will be ok will not max out thats y