Q about fuel pressure regulators...

[ILikeMy240sx]

I am thinking about going with a stage I BD kit with 52# injectors, Z32 MAF, and Walbro 255 fuel pump with Enthalpy ECU for S14...

Would I need to get a fuel pressure regulator with that as well? What are some advantages of getting one and disadvantages of not getting one?

thanx for your help

EDIT: BTW, I meant one of those adjustable FPRs.
Modified by ILikeMy240sx at 3:23 AM 2/19/2005

[Jeff240sx]

Unnecessary. You go find the pros and cons now.-Jeff

[Red-KAT]

My stock FPR was making me lean at 5500+ rpm... Not enough flow... Just swapping it to a Aeromotive fpr I can red line fine now... But mine could have been going I guess...

[ILikeMy240sx]

thanks for your replies...

So I know the FPR allows you to manually change the fuel pressure but what is the usefulness of this feature?

[DammitBobby]

If I am not mistaken the Stage II kit comes with a FPR and mechanical fuel gauge.

[ILikeMy240sx]

Yes it does... trying to decide if I really need it or not

[DammitBobby]

It is required to keep a constant fuel pressure. The ECU is not designed to work with fluctuation in fuel pressure. I am sure the fuel pressure at idle needs to be set according to the tunning of the Enthrapy ECU. If you didn`t need it, it would not have been included in the kit. It also comes with a mechanical fuel pressure gauge. Always helpful when tuning and trouble shooting fuel injection systems.

[Jeff240sx]

The ECU is not designed to work with fluctuation in fuel pressure.

Are you sure? Because the stock fpr is a 1:1 rrfpr, which increases fuel pressure per pound of boost. Seems like fluctuation to me.And to say it's necessary because it's included is incorrect. Very rarely does a stock fpr get outflowed. Skyline pumps will do it.. but that's not the subject here. However, raising fuel pressure doesn't require the ECU to know. In fact, its a way to richen the whole system without use of an electronic setup.Do you people even know what you're talking about, or do you just go around regurgitating what you've been told by people trying to sell you stuff?-Jeff

[nissanfanatic]

I woudln't consider it a fluctuation. You have to remember that the pressure in the intake manifold is also pressure on the fuel coming out of the injectors. Raising fuel pressure overcomes the pressure im the intake manfold allowing for the same amount of fuel to be delivered when in boost. In a sense, fuel pressure behind the injectors drops. Not literally, but its a way to think about it. On the contrary, fuel pressure drops when vacuum is present. I would consider a RRFPR an equalizer. Nothing more.

If you outflow the stock FPR, chances are you will probably outflow the stock fuel rail too. That is a lot of fuel.

[ILikeMy240sx]

Hmmm so unnless I have a bad stock FPR to begin with a setup consisting of1. 50# injectors2. 255 fuel pump3. Enthalpy ECUwould not require a FPR?

Also with that setup and at 12PSI max... I dont think ill max out the stock fuel rail... what do you think?

[nissanfanatic]

You're fine. orion just made 298whp on a JWT ECU.

#50 injectors are.... IIRC top feed 50lb injectors correct?

I don't think the stock fuel rail has been maxxed out yet. You will max out the Walbro first. I would think the fuel rail works exactly like injectors. If it is too small, pressure can compensate.

[DammitBobby]

Maybe I am missing something here. BD has several kits.

This fuel upgrade kit will bring the stage 1 kit up to the stage 2 specifications. This kit includes Boost Designs fuel rail, Aeroquip lines and fitings, RC 50# injectors, Injector clips, and Fuel pressure regulator. this is a bolt on kit with no modifications needed to install. this setup can be controlled with either the SAFC, Emanage, AEM, or whatever fuel management you choose.

You need one with this kit. If you are talking about using your stock fuel rail then yes you don`t need external FPR. I have a Walbro 255 fuel pump and stock FPR, but I would suggest at least a mechanical fuel gauge.

[Nismo_Freak]

I would suggest an aftermarket regulator like the Aeromotive unit. It will smooth out your rail pressure and prevent over pressurization at idle common with hi-flow pumps.

[ILikeMy240sx]

Thank you all for your replies.

The BD stage 2 kit comes with everything I could possibly need but since I do no think I will need the top feed rail or the adjustable FPR.. I was just thinking about getting injectors and pump from the stage 2 kit. I would definitely put in a fuel pressure gauge to monitor fuel pressure.

So if I do get an aftermarket regulator, besides for preventing the idle over pressurization, what would I be able to accomplish with it? Im pretty much asking how would I use the regulator to smooth out the rail pressure?

sorry for sucha newb question but... I need to know

[Nismo_Freak]

Thank you all for your replies.

The BD stage 2 kit comes with everything I could possibly need but since I do no think I will need the top feed rail or the adjustable FPR.. I was just thinking about getting injectors and pump from the stage 2 kit. I would definitely put in a fuel pressure gauge to monitor fuel pressure.

So if I do get an aftermarket regulator, besides for preventing the idle over pressurization, what would I be able to accomplish with it? Im pretty much asking how would I use the regulator to smooth out the rail pressure?

sorry for sucha newb question but... I need to know

You can correct lean mixtures in 5 seconds and you get the benefit of a larger port for the fuel to flow through resulting in less pressurization in the lower RPM from the backfeed of fuel due to the hi-flow pump and the low injector duties.

Wow thats a long sentence lol.

It's not as much of a performance part as much as an insurance part IMO. You don't have to worry about a 100+k regulator being submitted to higher than designed fuel pressures and failing on you. The regulator is cheap and can be used later to enrich mixtures.