Okay I did a little searching today and came up with the following question(s). I'll admit while you read this I'll prolly go check out HP.com but it may be a good idea to have this info here. I searched and found a little bit on it but I have a few things to clear up.

In respect to Forced Induction, what are the differences between the two. Both adjust the Fuel Pressure according to boost, but I can't tell the differences. Are they the same damn thing and I'm an idiot. They sound like they do the same thing but the FMU seems more specific.

 

Dont feel bad dude I dont uderstand why you would ever need a RRFPR. If you have a regular aftermarket FPR and highflow pump and either an SAFC or an EManage I dont think you really need a RRFPR. Rising the FP in the rail to get more juice is just a handicap isn't it?

 

I don't think so. The way I look at it is the more pressure flowing through the lines the more fuel gets to the injectors. With that said the gas must be pushed as well to keep up the pressure.

So if we have a RRFPR then as the rate of fuel increases the pressure is increased. With an FMU it senses boost and then increases the pressure.

The more and more I think about it the more reason I have to believe they do the same thing.

 

Both the FMU and RRFPR do the same thing, they raise fuel pressure according to boost pressure. The differance between the two is that if you run an FMU you still require the use of your stock FPR because it can't raise or lower pressure in a vaccumm enviroment, a RRFPR can perform both functions of the FMU and stock FPR in one unit. Most people run the FMU because it is easier to install, you just cut your fuel return line and put the FMU between the fuel rail and retun line but with a RRFPR you have to remove the stock regulator and find special fitting's so you can bypass it.

 

Beauty, that is what I was looking for. Like I said, the more and more I read up on them the more they started sounding alike.

 

So what's better then?? An RRFPR or an FMU, will you ever run into problems with the stock FPR?? Is it better maybe to upgrade the FPR rather than throwing on an FMU? Or does the FMU do the grunt work saving the FPR to do the same thing it always does?

P.S. Thanks for posting Tim

 

get the RRFPR because its an FMU built into an adjustable FPR.. best of both worlds.

 

with bigger injectors, do I need the FMU, right??? or is useless using the SAFC2 and fuel pump to tuning the fuel???

 

need a little more info other than "bigger injectors" to make that call.