I am going to be running 5lbs of boost with 30lb injectors and sfmu (harder spring and largest disc). 16g turbo from HAHN.
I searched and many people say about 22 psi idle pressure is good but no static is given.
I just want to make sure of the settings:
- Static pressure is with the vaccumm line OFF - Idle is with the line PLUGGED IN
- I want to run 5lbs boost with an fmic and 30lbers. I am supposed to always tune the fuel using static pressure with the vac line off, CORRECT?
If so, what should I tune the static to for my setup? I was told once you set the static and then vac line is reconnected, the pressure gauge reading should drop like 10psi.
Would I set the STATIC to 22psi OR set the static to whatever is necessary for the idle pressure to DROP DOWN to 22 psi once the vac line is hooked back up?
When I want to bump up to 8psi, should I just change to the next second largest disc/ring combo? Will I need to change the idle/static pressure at all?
#72522, "RE: Fuel pressures with 30lber and SFMU" In response to Reply # 0
Ya know, that's one of the issues I've always got confused in. Like, I always thought static was at 0 psi? And I've never gotten the deal why you set the fuel pressures with the vac line unattached, but idle pressure are different.
(me keeps an eye on this thread imo).
-------jezreel 1998 GS with hrc stage 2, sfmu, ml, prokits, egt, boost gauge, apexi tt, haydans tranny cooler, costum dp, dr. uber groundwires, dynotune fp gauge. gst muff, turbo spoiler Boostin since Aug 03.
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#72524, "RE: Fuel pressures with 30lber and SFMU" In response to Reply # 2 Jun-11-04 09:29 AM by Ryan_Hes
I run that exact setup. 30lb injectors, SFMU, largest disk and dark spring - I also use a SAFC.
My car doesnt like running low fuel pressures...it has trouble starting and has a rough time idling. So, Instead of running 22psi like most, I run 30psi, then lean the lo-throttle 1,000rpm band to negative 30% to compensate. After datalogging, my short term fuel trims settled to just about zero, so it worked perfectly and my car has a much better idle.
So.. 30lb injectrs w/Vortech SFMU at 30psi with the SAFC at %-30 at 1000rpm
p.s. Also, all this talk about not having the vacuum source plugged in....I do all of my seting with everything hooked up. Why try to calibrate the SFMU...then hook up another variable and calibrate again. Hook it up how it's meant to be and tune it.
#72527, "RE: Fuel pressures with 30lber and SFMU" In response to Reply # 4
Ok... so ill set it to 22 psi idle to start with... but i still have another question:
If i have it at 22psi at 5 lbs boost and I want to go to 8 psi, will I have to raise the idle pressure at all? Or will the sfmu compensate by itself... I would think I would have to change discs at least right? thanks.
"Who needs a 4G63? I'd rather walk the competition than my crank..."
#72528, "RE: Fuel pressures with 30lber and SFMU" In response to Reply # 5 Jun-11-04 10:39 AM by turbo8u
nope you wont have to change the idle pressure. the SFMU rises a certain psi per psi of boost, thats the whole point of it. its called a rise rate, and the discs and springs and bleed valve setup are all there for the fine as well as base adjustments
the SFMU basically sets up a foundation, backbone for tuning if you will.
_ _ _ _ _ _ _ _ _
96 Black ESi 91 Red TSI AWD (RIP) 02 WRX
"turnin wrenches for nine hours in the pouring rain, just to get the beast up and running again"
Aerospace Certified TIG welder for Precision Castparts in Portland, OR.
And I've never gotten the deal why you set the fuel pressures with the vac line unattached, but idle pressure are different.
