some ideas on fueling..

[TomsMR2]

i was reading some FMU threads.. and something grabbed my attention.

7:1 fmu's make some CRAZY high rail fuel pressure.. i think im a little worried about running such obsurdly high fuel pressure. but its cheap... and it works. the high pressure is still worrysome.

so heres my idea..

new injectors! bigass new injectors. we all know that large injectors with no tuning will make you run stupid rich off boost.. tuning for large injectors is expensive.

so how about this.. get 20% larger injectors.. and run 20% less fuel pressure. in theory, this should run as stock. add a FMU, and you'd be seeing alot lower peak pressures at the injectors.

my only concern with this is atomization.. its all just theory, and i have no r&d or anything to back it up.. i dont even know stock FP

with larger injectors, and lower base fuel pressure, would the spray pattern be altered to the point where fuel is basically dripping out? this would only be a concern at off boost/low rpm operation, as the FMU would start bumping pressure after that and run normal.. but if its not atomizing at low rpm, it could run lean.. but who knows.

so.. would it work? whats the absolute lowest base fuel pressure you can run? common injector upgrade seems to be 370cc or so.. maybe this theory would work with something smaller.. say like 330cc's or something.

toss some ideas around, i wanna see if this works

[WDRacing]

Use a hacked maf, don't turn down the fuel pressure.

[TomsMR2]

going on an s13.. i belive you cant do that due to the plastic maf, correct? back on topic tho.. why not?

[oi138]

s13 MAFS housing is not plastic. s14's are.

[TomsMR2]

.. wait.. so the whole hacked maf thing was done on s13 de's?? i had it backwards

[oi138]

no they did it on s14's. But s14's are the one's with plastic mafs.

[WDRacing]

you can do it on either

[TomsMR2]

i still wanna know why my original idea wouldnt work..

[C-Kwik]

Well it makes sense that it could work. Not sure if there might be effects on the spray pattern for the injectors. Too low a pressure may create a poor spray which may lead to poor atomization of the fuel under vacuum. It's certainly worth investigating...

[WDRacing]

A better bet would be to get a rising voltage regulator to install inline between the pump and the battery. As boost raises so does the voltage to the pump and so does the volume the pump will put out. I've got a schematic for that somewhere on my PC, I'll find it and post it up. Or even a voltage booster if you don't wanna bother with the rising rate stuff and MAP sensor. Its really easy actually.

WD

[TomsMR2]

^ ???? sounds like a great way to overload your pump, in a hurry too.

also, the regulator would.. well.. regulate :P i dont think it the rail would see additional pressure past the regulator..

[WDRacing]

Possibly....

[JPRempe]

^ ???? sounds like a great way to overload your pump, in a hurry too.

also, the regulator would.. well.. regulate :P i dont think it the rail would see additional pressure past the regulator..

I don't think a fuel regulator would do that, but I could be mistaken. If there wasn't and increase of pressure at the rail, how could the injectors push a higher volume of fuel (if the stock rail was of the same internal dimensions)?

[TomsMR2]

^ by lengthening the pulse of the injector

the FP regulator is just like any regulator, it has a set max pressure, and wont let any more past.

[JPRempe]

Lengthening the pulse...I'm fuggin' retarded. OK, it's been a tough day at work. I know about how the reg's work, but I didn't post anything on it b/c I figured that you knew that I knew (who knew?). Thanks for smacking some sense in my head today...