Pengo

ok, i'm running an intercooled greddy kit on my sohc with walbro 255 intank HP and i just got my b&m gauge and fpr. with both the blue box and walbro, i'm thinkin i must be running really rich, so i was thinking of leaning it out a lil. what i want to know is wat my fuel pressure should be set at idle, and how can i check my fuel pressure while im driving (boosting)?

also, i have no idea how to do calculation for fuel injectors, etc, so i wanted to know if anyone can tell me if i'm close to maxing out my stock injectors, and if so, what injectors would be good? oh yea i'm running 6-7 psi right now. i was thinking 310s mite be ok as long as i keep my boost where it is. thanks

-alan

boostaholic

Base fuel press. + (FMU rate x max boost) = fuel press. at max boost.

So if you're fuel press. at idle is 45psi and you're boosting 7psi w/ a 12:1 rise rate FMU :

45 + (12 x 7) = 129psi fuel press @ 7psi boost

Pengo

can my injectors handle this much pressure? how long before they give out? i'm not sure if 310s are worth buying if i stay at this level of boost. of course alot would prob say i should get them just in case, but i'm wondering if they're necessary as in, 'get them or your injectors will fail in the next month'. keep in mind i'm not hitting max boost daily or constantly boosting.

oh yea, thanks for the calculation man. i guess i could be somewhere close to there but i have no idea what the damn blue box rising rate it

anyone else have any input or suggestions? thanks

sak

This site should help you decide if you are running too high of a fuel pressure and what size injector you should get. The injectors are only there for you to run less fuel pressure on your system. The stock should not be used for more than 60-70psi because that is ~ 80% duty cycle for the stock injectors. You should not run any injector at their max duty cycle (80%) because their life expectancy will go down the drain.

http://www.rceng.com/technical.htm

Pengo

do you mean 60-70 psi at idle, or you mean max during driving? i'd hate for my injectors to die on me while and boosting

Pengo

ok i checked my fuel pressure today with vacuum line off and plugged. its in the low 50 range. can i safely lower it to 40 or 45? keep in mind i'm probably running really rich already with the blue box and walbro

sak

I would suppose you could, but there is no definate fact that you are runing rich unless you get it tuned on the WBO2.

Pengo

thats troo, i have no definite proof of running rich, but the blue box is known to run rich already, and i have the walbro HP intank. this combination plus the fact that i'm running relatively low boost would lead me to put my bet on my car running rich. see, all i'm trying to do is figure out if my stock injectors will be sufficient and even if i do upgrade to 310s, i wanna know what fuel pressure i should be running at then so i won't lean out, but i don't wanna run super-rich either. i'd rather run rich (like i am rite now) and stay on the safe side rather than run lean, but if i could make my car run a little better and more efficiently i would like to know exactly how. thanks to all who have helped