JeremyL

what is a good rising rate for someone running 7-8lbs of boost? ive seen some that were like 12:1 but at 8lbs that almost 100psi of fuel and not only would that not be safe to your engine but your mpg would be pretty lousy too i would think

are they safe and reliable to run? how long have u been running yours? what kind of issues have you had? would it be better to run with a SAFC?

TeStUdO

i ran for over a year with a 12:1, fuel pressure was crazy high and dipping into boost the transition was shitty. you should either switch to the vafc hack, or save some money and buy the smc dsm 450's and a resistor box. you will be rid of the high fuel pressure and the transition from vacuum to boost is much better.

Tofurky

i was using a 12:1 on my old set up. held up alright for aboust 3 months with 7 psi. at the track i thought i could try a 9psi run. oops, byebye rings.

JeremyL

well i seriously doubt that 12:1 is necessary cuz at 9lbs boost thats just way too much gas going in, well i dont and wont have vtec so a vafc hack wouldnt be necessary but i was thinking about a safc but dont you need to run a safc with an fmu, how does a safc adjust fuel delivery?

move_right

an afc from apex or whatever adjusts fuel delivery by modifying the signal the ECM receieves from the MAP sensor. the map sensor says 'hey, I got -x- amount of air coming in the engine' so the ecm adjusts the injector pulse to properly accomodate the air volume. an afc will have the MAP tell the ECM whatever you want it to. at anyrate, I would recommend the smc and 440cc injectors. just remember, the only REAL right way to do this is with bigger injectors and an engine managment system that you can program your ignition timing curve to compliment your fuel curve.


[Modified by vinny, 4:05 PM 12/8/2002]

b16ahybrid

If you do use a fmu your limited to using either the 10:1 or 12:1 with stock injectors.If you run larger injectors then you can lower the rate to 8:1 or even 6:1 depending on the size of injectors.The rising rate is not determined by the amount of boost you plan to run, it's determined by the size of injectors your runing.The lager the injectors the lower the rising rate, and vise versa.

JMinSi2000

If your fuel pressure gets too high your fuel lines can blow under the hood then all the gas will catch on fire and there goes your car. So if you do use an FMU, which I really dont recommend, get bigger injectors so you can use one with the smallest ratio possible, and dont boost over 7-8 psi.

b16ahybrid

If you do use a fmu it's very wise to use hose clamps on the fuel lines.....the stock clamps will not work...

2001TypeR

How high of fuel pressure is too high? Also will 450 DSM injectors make the car run shitty out of boost with just the FMU???

b16ahybrid

your car won't idle with 450's to much fuel.
Optimum fuel pressure (highest) i would say is 80psi, reality 110psi or so...If done rite your fuel pressure shouldn't go higher then about 70psi or so (with larger injectors and stand alone tuned).with a fmu your guaranteed to see 100+ psi of fuel pressure in order to get enough fuel..

Andrew 825SM

Best is to use 450cc injectors, 4:1 fmu, and afc to lean out the fuel. I run 10 psi daily doing this.

SIK IN DA HED

or you can get some 310s and 8:1... lean it out with a SAFC. with all that money youre spending.. you should just get a hondata and 440s.

b16ahybrid

swrdply400mrelay

Yea I was gonna do the VAFC hack but I calculated getting a Hondata and buying and OBDI ECU. Turns out the Hondata route was more expensive by about $3-400, but I could sell my FMU and missing link. Plus Hondata is just plain *** better

JeremyL

sure if i lived in so cal i could walk down the st and find a hondata tuner but around Nashua, Nh there arent any guys who can tune hondatas

JeremyL

ok so with an MSD fuel pump and 440's i should be safe with a 6:1 rise right? at 8lbs thats only 48psi...is that engouh fuel or not enough? i would go with a SAFC cuz i found a guy that can dyno tune them