I am just wondering and i need all the inputs i can get on this. I have been reading about needing a FMU for boost applications....Here's my question. Right now i am wondering, If i keep the stock fuel system with an exception of injectors, a bigger fuel pump and a phearable ECU, wont i need to rise the fuel pressure system up one psi per pound of boost becasue if i pressurize the manifold with boost, wont every pound that i increase the boost, decrease the psi of the injectors when they open.....so like if i have a 43 lb fuel system pressure, if i were to boost like 20 lbs, then when they are opening trying to put fuel out, they woould only be opeating at 23lbs of fuel system pressure.....so my question is...do i need a 1:1 aeromotive fmu.....

 

bump for some help!!!!

 

does ANYONE know?

 

You don't need an FMU (which typically have a rising rate of 4:1, 8:1, 12:1, etc) you need a fuel pressure regulator that can be boost referenced to increase fuel pressure linearly with boost pressure.

 

oh i c.......can you point me to a good brand and place to buy one.......thanks in advance...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by themorphious &raquo;</TD></TR><TR><TD CLASS="quote">wont i need to rise the fuel pressure system up one psi per pound of boost</TD></TR></TABLE>
The stock FPR does this.

 

dont use an fmu! there horible, fmu is the worst way to supply more fuel to ur motor, people blow up boosted cars with top of the line **** (such as my old motor) and fmu is bottom of the line. get complete fuel management and ull romp. good luck bro.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jdmgsrallmotor &raquo;</TD></TR><TR><TD CLASS="quote">dont use an fmu! there horible, fmu is the worst way to supply more fuel to ur motor, people blow up boosted cars with top of the line **** (such as my old motor) and fmu is bottom of the line. get complete fuel management and ull romp. good luck bro.</TD></TR></TABLE>

Did you read his first post? He's looking for a FMU to linerally increase fuel pressure with boost, which would keep his fuel pressure constant with his boost.

So it'll be like this:

Boost:Fuel Pressure
0:43
1:44
2:45
10:53
20:63

OP: I've recently been thinking about the same thing. I think for 20psi it would be a good idea to get a 1:1 FMU and have it tuned. Only thing that would happen is that your injector duty cycle would decrease if it's tuned well, and that's a good thing.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Everyones Hero &raquo;</TD></TR><TR><TD CLASS="quote">Did you read his first post? He's looking for a FMU to linerally increase fuel pressure with boost, which would keep his fuel pressure constant with his boost.

So it'll be like this:

Boost:Fuel Pressure
0:43
1:44
2:45
10:53
20:63

OP: I've recently been thinking about the same thing. I think for 20psi it would be a good idea to get a 1:1 FMU and have it tuned. Only thing that would happen is that your injector duty cycle would decrease if it's tuned well, and that's a good thing.</TD></TR></TABLE>


Ok, you are close to what i am saying.....i am saying that if you increase the pressure in the manifold with the turboby 10 lbs, wont that output the fuel pressure on the end of the injector by 10 lbs less.....so lets say, if i have stock 43 psi, and i boost the manifold pressure to 10 lbs, then wouldnt the fuel pressure at the end of the injecotr be 33 psi fuel system.....so like with out a 1:1 fpr then the nubers would look like this...

boost: fuel pressure at end of injector
0:43
1:42
3:40
10:33
20:23
30:13
40:3

So if i were to have "theoretically" 43 lbs of boost, the manifold pressure would be the same as teh fuel system pressure, therefore the fuel system coudnt push any fuel out of the injector...so if i had 50 punds of boost, then the boost would be pushing the air into the fuel rail...because the injector is open and the air pressure is higher than the fuel system pressure....is this making any sense?....just go with me here...beacsue i think this REALLY could create a problem...

 

more help!!!!! PLEASE!!!!!!!!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B20C5 Turbo &raquo;</TD></TR><TR><TD CLASS="quote">The stock FPR does this.</TD></TR></TABLE>
are you sure that the FPR does this......so i dont have to purchase a aftermarket FPR?!?!??!! if so that woule be great news.....how high of boost will the factory FPR handle?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B20C5 Turbo &raquo;</TD></TR><TR><TD CLASS="quote">The stock FPR does this.</TD></TR></TABLE>
The factory fuel pressure regulator is a 1:1 unit designed to maintain a constant pressure differential across both ends of the injectors (what you are looking for). The only reason to replace it with an aftermarket 1:1 regulator is when an extremely high volume pump will be used (MORE than 270LPH) and/or when you find that you need to adjust the base fuel pressure setting.