fuel pressure regulator question.

i was talking with somone about fuel pressure and why its important when he used the term "rrfpr" raising rate fuel pressure regulator. i had never heard that term used before. when i asked him what it ment, he said its raises fuel in refrence to boost. so i asked him the diffrence between an AFPR like Aeromotive A1000 that has vac/boost ratios 1:1, and his rrfpr. he didnt know. so i thought i'd ask if an afpr that has boost ratios are also called rrfpr.

the old search button said goto hell, no results.

i hope you guys follow me with what im trying to ask. is there a diffrence?

I think that a raising rate fuel pressure regulator is one that you can only raise the rate and can not drop it like a aeromotive.

nope. the aeromotive afpr is a rising rate regulator. any forced induction car needs a rising rate regulator. for NT guys standard ones are cheaper but since most of us doing fuel mods have turbos or plan to add them we only talk about the rising rate reg's.

well i spent a couple hours looking/searching around.

from what i've gatherd, RRFPR's are the same as most Afpr but have ajustable boost/fuel pressure settings. their not static in reffrence to boost. so with RRFPR insted of having a static 1:1 ratio you can change it to 1.7:1 or 3:1 or whatever you want.

so from what i've gatherd if i put one on my car with the 3:1 ratio with fuel pressure set at 43psi i would be raising fuel pressure 3psi for every psi. so at 15psi my fuel pressure in my fuel rail would be about 88psi. i didnt find alot of information about it, it seems to be people are using this so supply more fuel to the injectors durring boost, why?? i dont know. i think a safc2 would be better. i dont think i would want fuel pressure moving around like that all the time..

look at Aermotive's website they all have 1:1 reffrences. matter of fact throughout all the places i went i think i heard of 2 rrfpr's, one was vortec, the other i cant reamber. i kept running across alot of Europen cars, like volvo's, saab, VW's that were running them. a Volvo fourm is actually where i got the most helpfull information.

no wonder i hadn't head of it. it dosn't sound to appeling. like i said before; i'd rather have a static base fuel pressure in relation to boost and ajust airflow signals insted of fuel pressre.

what your talking about is a adjustable rate rising rate fuel pressure regulator. lol think of it this way

fpr = stock no adjustment set from the factory
rrfpr = stock on turbo or forced induction cars, no adjustment
afpr = allows you to adjust base fuel pressure. non rising rate.
rr afpr = adustable for base fuel pressure. rises with boost. not adjustable for boost rise rate. this is the most common type that we use. i think the aeromotive is this type.
ar rr afpr + adjustable for rate of rise and base fuel pressure

what your talking about is a adjustable rate rising rate fuel pressure regulator. lol think of it this way

fpr = stock no adjustment set from the factory
rrfpr = stock on turbo or forced induction cars, no adjustment
afpr = allows you to adjust base fuel pressure. non rising rate.
rr afpr = adustable for base fuel pressure. rises with boost. not adjustable for boost rise rate. this is the most common type that we use. i think the aeromotive is this type.
ar rr afpr + adjustable for rate of rise and base fuel pressure


I think you nailed it on the head. Just about all of the popular fuel pressure regulators used by DSMers are rising rate adjustable fuel pressure regulators.

Although, I do believe the stock FPR can be considered a rising rate FPR because it raises fuel pressure with boost pressure. The reason we end up having to buy new FPR like an Aeromotive is so that we can set base fuel pressure to stock if a large fuel pump is used.

fpr = stock no adjustment set from the factory
rrfpr = stock on turbo or forced induction cars, no adjustment
:evillol:

:evillol:


Ah, I must have overlooked that part of your post :tongue:

blah blah.. bunch of technical terms. In reality the reason to replace the stock FPR is because we need one that flows more. Doesn't need adjustable base pressure, it doesn't need anything but rising rate in direct proportion (1:1).. etc. I can only imagine you use a 1.7:1 AFPR on a big fuel setup.

so can a fpr with a raising rate of (1:1) aslo clasified as a rrfpr?

so can a fpr with a raising rate of (1:1) aslo clasified as a rrfpr?

Yes, any fpr that raises fuel pressure with boost pressure can be considered a rrpfr :)

I think there are 2 conversations going on here. But I'm a little tired :D

We use a 1:1 AFPR. The "rate" doesnt rise, just the pressure. We do this to keep the pressure ACROSS the injector constant. If base pressure is 43 psi, and boost is 10 psi, we dont want to have 33 psi across the injector, since flow will go down. More boost, less fuel. WTF! :D If fuel pressure follows boost, the pressure across the injector is always constant, and so is fuel delivery.

The term "rising rate" means that the ratio is increasing. The ex had one of these with her Vortech SC kit on the old '00 Si. Its just a hack way around upgrading injectors and using an AFC/similar. At 140 psi even the little 270s or whatever they were would flow enough to keep up with the SC. There was an inline high pressur epump installed, since most in tank pump (like all the walbros we use) have a bypass valve at something around 80 psi, limiting the max fuel pressure you can run. You can change the rate 10:1 to 12:1, or whatever) to "tune" the AFR. At any rate, she eventually went with larger injectors and an AFC, and ultimately an AEM.

We just need a regular 1:1 FPR for our cars, the ECU is already setup for this. We have problems when the FPR can not keep it 1:1, like when it is overrun at idle/cruise. The ECU still assumes you are at 43 psi, when its really now 50 psi. Etc.

so what would be the benifit of using a rrfpr on a N/A ecu inplace of an safc2? the way i see it using a afpr with 1:1 ratio and safc2 would be ideal. but quite a few people on other boards say they would rather have a rrfpr inplace of an safc2. is there a benifit on N/A ecu's??

Just to get out of using larger injectors (keeping the kit "bolt on," emissions legal, whatever). An AFC can only add fuel up to 100% IDC. A rising rate FPR can continue to add more. But I Do disagree with changing base pressure to change AFR.