RRFPR vs FPR???

[Cubantunr]

Ok now I have researched and only found a little info on the differences between an adjustable fuel pressure regulator for my Sr20det (small upgrades ) and a rising rate fuel pressure regulator. Fpr on our Sr is 1:1 ratio correct? All I'd really like to know is would it be alright to run the Tomei type L fpr on my Sr20det. Already ordered it :/
I can't seem to find the ratio for this rrfpr, talked to a man at tomei and he said it'll work fine for stock Sr20det but he didn't seem to speak English well. And the other companies seemed to be stumped so I'm askin my fellow zilvians.
Also the type L rrfpr holds from 200-800kpa 29-100psi roughly. So I know I can set it to 36psi.

[GroundPerformance]

Actually RRFPR are regulator found on the Roller Rocker SR20s.. :hide:


On a serious note RRFPR is just another term for FMU. RRFPR or Rising Rate FPR are regulator that can increase pressure over 1:1 ratio. Most company calls a adjustable FMU RRFPR and while the typical FMU are the ones that are set with a fix ratio or adjusted using different size diaphragm. This type of regulator are used for cheap turbo setup that need the extra fuel by means of fuel pressure. Not really recommended since Nissan ECU are fairly tunable and plenty of other choices. GL!

[GroundPerformance]

Personally if ever someone require this extra functionality of an RRFR regulator Synapse Engineering is the way to go.


http://www.boostcontroller.com/products/SC004.gif
Synapse Engineering's Synchronic Fuel Pressure Regulator eliminates the need for a conventional diaphragm and uses an aluminum piston and aerospace seals.



Universal Model with threaded -8 inlets and -6 return fittings with an offset fuel passage for maximum flow.

Dedicated 1:1 rising rate ratio
Built-in 1:1 to 12:1 FMU at 1/5 the size
Adjustable static fuel pressure from 16 to 100 psi
Flow adjustable return fittings
Gas, Alcohol, and Methanol compatible
Ratio adjustable

[Cubantunr]

But I cannot find what the tomei type L fpr ratio is at, I've heard lots of bad things about rising rate fuel pressure regulators, has anyone here dealt with them and how was it? Should I just go with type s?

[GroundPerformance]

But I cannot find what the tomei type L fpr ratio is at, I've heard lots of bad things about rising rate fuel pressure regulators, has anyone here dealt with them and how was it? Should I just go with type s?

What's your WHP goal and what size injector you have or plan on using?

[Cubantunr]

Right now I'm at about stock t28 9:1 compression built head. Prob around 300, but within the next 6months I plan to overhaul to 550hp
Injectors are 370 now.

[GroundPerformance]

You should have just stayed stock FPR.. But anyways if you want to know the ratio setting or how to adjust it. Get a Fuel Pressure Gauge and Pump. Adjust the fuel pressure to 43.5 PSI with the VAC hose line off first. Then using a pump load 1 PSI on the regulator and if fuel pressure increase to 44.5 or plus 1 then you know its @ 1:1 if higher then lower it. Most manufacturer I hope should leave it @ 1:1 factory. GL!

[Cubantunr]

Ahhh, I think ill just call tomorrow and tell them to switch for the type s since I'm sure that one is a 1:1
My Nismo fpr just went out and I think that's why my cars running rich with idle up to 1500. So I don't have time to play with this or take the risk.. what's your thoughts?
Tomei 185001 Fuel Pressure Regulator Type S (Standard Diaphragm) (http://www.frsport.com/Tomei-185001-Fuel-Pressure-Regulator-Type-S--Standard-Diaphragm-_p_15259.html)

[Cubantunr]

Nevermind just foundthe specs, says they're both 1:1 ratio and both 200-800kpa so shouldn't really matter.. aside from type L being good for up to 800hp. Just don't see why people talk down on rrfpr fmu?

[GroundPerformance]

I just read the Tomei Type L FPR Specs and it's a standard 1:1 FPR. "L" designation just means larger diaphragm for a more stable pressure good for high HP applications. Just keep it and you should be good.

[Cubantunr]

Thanks for all the help hopefully it turns out good.

[Croustibat]

On another note, dont use RRPFR, esp. if you plan to get high boost.

Remember how your fuel pressure is actually 3bar + your boost ? With a RRFPR it is 3bars +rate x boost . And it gets very easy to reach pressures most pumps cant reach properly.

[Cubantunr]

And if i leave the tomei at 1:1 just like the nismo fpr ratio then shouldnt they both be the same thing. So whats the problem as using this as opposed to another fpr if im just going to keep it at the 1:1 ratio i dont see how there would be a difference.

Nismo fpr set to 36psi running with ratio 1:1
Vs
Tomei type L set to 36psi running with 1:1 ratio both should run car exactly same no? If not plz explain sorry kinda new to fuel management..

[Croustibat]

The thing is, you wont be able to set them exactly the same.

Another thing to consider is the speed the regulators react to a pressure drop/increase. they dont have the same "delay", and tis usually requires a retune.

Short version : keep the oem FPR, unless you really know what you are doing and are in need of a custom tune anyway. Changing the FPR is an upgrade you need to do when the oem FPR is overrun, and this usually happens with a dual pump setup and big badass injectors.

Otherwise it just is asking for troubles.

And it does not bring any power.

[guitaraholic]

Doing cheap "quick" fixes, like rising rate FPR to get extra fuel from injectors that are too small, are the reasons the sr20 has received the reputation for being unreliable.

Will it work, maybe, you might get lucky and get the fuel mixtures just right, but some things to think about

- As your fuel pressure rises, your fuel pump will flow less and less
- pressure and flow do no rise at the same rate. If you double the pressure, you are not going to get double the flow rate.


If you don't have the supporting mods to crank the boost, then wait. I waited for about 6 months running at 9psi. Then when I got the upgraded injectors, MAF and ECU, along with all the bolt ons, I was able to run it at 13psi, and did so for years and years. I've put over 100k on my SR, and it's still running strong.

If you want to get cheap. STI injectors work, Z32 MAFs are cheap, and daughter-cards/EEPROM chips aren't too pricey.

[jr_ss]

If I'm not mistaken, the factory FPR is of the rising rate style, correct? If so, anything offered for our cars are of the same style with the exception of being able to adjust base pressure. You want your fuel pressure to increase as the amount of boost increases, therefore your factory FPR is a RRFPR.

[guitaraholic]

While technically you are correct. It is only 1:1, meaning as the boost pressure goes up by one, so does the fuel pressure. This is done to keep the injector flow constant. Otherwise, during boost, the injectors would flow less because they would have to fight against the air pressure in the manifold.

A rising rate is one that you can select 2:1 or 3:1.

Yes, you do want a FPR that raises it with boost, but only 1:1. Any less and you stand to run lean, any more and you will have some skyrocketing fuel pressures and other variables that would make things less than optimal.

[jr_ss]

My point being, either way you look at it the stock FPR is a rising rate regulator. FMU's are the other aspect of them. I don't want op to get confused and get something that doesn't increase fuel pressure based off boost.

FMUs/fuel management units were/are an archaic way to add fuel without going to larger injectors.