Going turbo

[99'EclipseGS]

I'm going turbo and the kit that I'm getting comes with a FPR. Is a FPR better than a FMU? Or is a FMU better? Or are they the same thing?

[VelocitàPaola]

It depends on what else you have to control fuel... if nothing else, then you need an FMU. If you have some electronic means of controlling fuel (i.e. Megasquirt), then you need an AFPR.

[99'EclipseGS]

Nah the kit just would come with the fpr and I would buy a fuel pump. I need a fmu then? They're different?

[tec_41]

You can get away with just an FMU or a SFMU. You cannot, however, just run an AFPR without an FMU.

A fuel management unit will raise the fuel pressure incrementally with the boost.

[rstare]

The difference between an AFPR and an FMU is the rate that they increase fuel pressure according to boost. An AFPR has a 1:1 rising rate, and this is just to maintain the spray pattern of the injectors. The FMU, (in your case you're going to want a 12:1 FMU) has a rising rate of 12:1, this means the fuel pressure goes up 12psi for every one pound of boost. With more pressure behind the injectors, more fuel will enter into the combustion chamber, even though the injectors are open just as long as they would be at WOT in a N/A 420a.

[VelocitàPaola]

Originally Posted by rstare

An AFPR has a 1:1 rising rate, and this is just to maintain the spray pattern of the injectors.

Maintaining a static pressure differential also means that, for a given pulsewidth, the same amount of fuel enters the combustion chamber at 10psi as it does at 0psi, eliminating the need for electronic compensation.