Do I need a fuelpump or FPR? what do FPRs do?


EK9turbo

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Jan 17, 2008
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Fuel Pressure Regulators
A fuel pressure regulator is a cheap way of getting more fuel into the engine but its not the ideal approach. The best approach is engine management like Hondata and bigger injectors (if your appllication requires it)!

Heres some info out of one of my IB articles..

Do not buy a fuel pump for your car unless your car meets these criteria. First, your car is over 300 Wheel Horsepower. Second, your car has an FMU (Fuel management unit) that comes with some turbo kits. It raises the fuel pressure on your car per each pound of boost, and your stock fuel pump won’t work. That’s it. Don’t buy a fuel pump unless you meet these 2 criteria. And if your forced to buy one, always get an in tank one, never an inline one that goes into the engine bay. Those are dangerous and should be avoided. The goal here is we want to keep the fuel system completely stock. Avoid the ridiculous fitting nightmare and the steel braid lines that come undone frequently, leak, and that cost a fortune. They do nothing but create problems. Stock doesn’t have any problems, so take advantage of it.
a. Always upgrade your injectors when you need more power, not your fuel pump. Generally, if you’re under 350 WHP you can get away with RC 550’s, fewer than 300 you can use RC 440’s, and fewer than 220 you can use RC 310’s. Stock Honda injectors from say a GSR or B16A can only make in the high 100’s with a fuel pressure regulator and it’s not recommended. RC 310’s are your best choice with a fuel pressure regulator if you don’t have management. You can turn down the fuel pressure until your air fuel is good again. With management, say Hondata, Hondata - Honda ECU Modification and Enhancement it’s smart for any all motor car to get RC 440’s. Not 310’s. The 440’s can handle a turbo later, or can handle a much larger HP number if you go that way. They also have a way better resale demand and price used.


And just to justify what im saying... my car was tuned at 11psi = 352.8hp and makes 14-15psi in 5th gear which probly works out at 450+ at an estimate..... and I still use the original fuel pressure regulator! but with a Walbro fuel pump high pressure/volume (255litres per hour capable) and RC750cc injectors.

You can see my factory regulator on the right of this pic. And the only reason I put a golden eagle fuel-rail on is because I wanted a guage in the middle of it so I can tell when I need a new fuel filter!


...to explain how it works you have a fuel feed thats from your pump, goes to the black fuel-filter on your firewall then to the fuel rail and to your injectors. Factory pressure runs between 38psi-46psi. Your pump pressurises your fuel rail at this pressure and your injectors work on a 'duty-cylcel' controled by the ecu, i.e. theyre opening and closing for X milliseconds to allow the correct amout of fuel into the cylinders. controlled by the ecu. The excess pressure returns to the tank through the FPR and down that return line. The other line on the FPR is a vacuum line, engines make alot of vac at light throttle openings and less manifold vac the more the throttle is opened. and no VAC AT WIDE OPEN THROTTLE.

so at low throttle the vacuum is OPENING the FPR allowing more fuel to return. at full throttle where more fuel is needed; the intake-manifold isnt giving the FPR any vacuum to open it (remembering the FPR is a bypass valve that allows excess fuelpressure to return to the tank). So on a turbo car like mine, the manifold is under pressure and of-course the FPR has a vacuum line that goes to the manifold so that too sees this pressure and this pressure holds the return SHUT.

For tuning with fuel management.... your controlling the injectors duty cycle to control how much fuel goes in to the cylinders.

also to note, factory fuel rails can be used to make 800+hp drag racing b18's so why do you need a so called HIGH-FLOW fuel rail! :p

Also as an interesting point... your fuel pump isnt always contantly working, its just maintaining an approximate pressure in the feed line upto the regulator!

If you have a fuel pressure guage and notice that your pressure is at or below 38psi then you NEED a new fuel-filter thats on the fire-wall :nice:

Hope this helps people understand their function and use.:nice:
 

Last edited:


Ben_Andersonâ„¢

B18C4 CIVIC â„¢
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As Oli said great info and we know we can trust it becuase your car is proof !

Cant way to come to you with a massive wedge and get a turbo b18 built Will.
 


blinx9900

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Well said!!!, I'm gonna find a good place to sticky this.
 




blinx9900

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are you cereal right now?
Are you cereal right now? cause you just quoted a post thats 6 months old, when he posted that this thread was not a sticky, it is now, fail for trying to be witty...
 


the_flatman

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Jan 5, 2009
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Great info men, im new here and im learning a lot !!! Just a question.... what is your gauge measuring when you are idle with your OEM FPR?
 



Lee s

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Jun 28, 2010
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Will ive got a Walbro and still have a buzzing from the pump, this normal with b20
 


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