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Fuel regulator set up


scobie140

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Thought i had this sussed then after i had a quick check to see how others had it set up I've totally confused myself :wacko:

 

This is how i have it mocked just now is this correct?

20170206_101705_zps792mw9nj.jpg

I did originally have the adapter in the driver side rail but looking at ChrisB's build thread i swapped it over.

chrisb_zps4f6fzyfb.jpg

I then noticed he has his connected into what i would have thought is the outlet of the regulator which should be returning to tank.

I then tried to find something on the web to clear it up for me but the best i could get was this from fuel lab.

Fuel-System-Bleed-Return-FUELAB_zpsdlqmo5ye.jpeg

 

My understanding is that it it would regulate the inlet pressure by letting away the excess to the return line meaning the inlet line would never be above 52psi or what ever you set it at. But their diagram would suggest that it regulates the output to 52psi

 

Anyone clear this up for me and tell me what to put where since I've pickled my head?

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I would agree with the latter. I've zero experience in these things at all but as a plumber I have a working knowledge of fluids and pressures/flow rates, and by fitting a regulator (a kind of pressure reducing valve) to the flow before the fuel rail then yes, you're limiting the flow across both rails and the return line to the tank to whatever you set the valve to.

 

That makes sense to me.

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I would agree with the latter. I've zero experience in these things at all but as a plumber I have a working knowledge of fluids and pressures/flow rates, and by fitting a regulator (a kind of pressure reducing valve) to the flow before the fuel rail then yes, you're limiting the flow across both rails and the return line to the tank to whatever you set the valve to.

 

That makes sense to me.

 

I'd have thought that the fuel inlet would have to pass through the regulator before entering the fuel rails in this was the case?

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When fitting a regulator, you normally have the regulator on the return side of the fuel rail, so a feed from the tank/fuel pump to the fuel rail an the regulator at the end of the fuel rail to maintain pressure, then the return line to the tank.

 

I can only presume that with the VQ setup, the original feed line is kept and the regulator will be fitted to the other end of the fuel rail before being returned via the FPR to the tank.

Edited by Tricky-Ricky
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No reason you can't fit it on the return, but it would be much, much harder to control the pressure/flow that way: All you're doing is adjusting the pressure as it returns back to the tank, after it's jizzed a load of fuel out of the injectors. It will have an effect before the injectors, but more luck than judgement.

 

Anything to do with controlling flow should be placed on the flow before any take offs.

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OK quick exsplanation, the VQ as we know has a feed line from the pump/tank only, fuel pressure is controlled by the semi intelgent pump, The reason for fitting a regulator is when going FI, as the std pump cannot compensate for large changes in engine load that FI creates.

 

So the general trend is to add a return and regulator to control the fuel pressure when the extra demand of the FI calls for it, so the regulator sits at the end of the fuel rail and restricts the flow back to the fuel tank maintains a pre set pressure, the regulator is also connected to the plenum by a vacuum line, and when positive pressure is made, the regulators internal diaphragm automatically increases the fuel pressure in line with the boost pressure maintaining the correct fuel flow for the injector demand at boost.

 

 

Suffice to say for normal N/A use on the VQ a regulator is not needed unless the power iis increased beyond the pumps normal control range.

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Great, thanks mate :thumbs:

 

However, I struggle to see how that would work efficiently. The regulator is only ever seeing the pressure post-injector usage, which will by nature be a lower pressure than pre-injector. Actually, where does the return go back to? That may be the obvious thing I'm missing.

 

Not arguing the toss, just genuinely trying to expand my knowledge :)

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No worries :) the regulator maintains the set pressure by restriction, but its the pump that keeps that pressure by over supply, which its always imperative that you have a fuel pump that's capable of maintaining far more volume and pressure than the injectors will demand,

so between the fuel pump and the regulator there is always a constant pressure, and this increases with fuel demand via the rising rate feature that's engine vacuum/pressure controlled.

 

Oh and the unused/excess fuel is returned to the fuel tank..

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Okay, that makes a bit more sense now. I assumed the excess was dumped back to the tank, which is why I was getting a bit confused.

 

I assume the regulator isn't put before the injectors simply so you don't end up in a situation where you get a massive need for fuel and the regulator can't open quickly enough to supply it. Perfect, thank you!

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Glad someone knows what they doing :lol:

So from my understanding of what Tricky Ricky said I've got it set up correct.

Does it matter which fuel rail its on? as it stands I've had to turn the dampener upside down to accommodate the adapter on the passenger side but if i put it on the driver side rail there is no restrictions that i can see

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Okay, that makes a bit more sense now. I assumed the excess was dumped back to the tank, which is why I was getting a bit confused.

 

I assume the regulator isn't put before the injectors simply so you don't end up in a situation where you get a massive need for fuel and the regulator can't open quickly enough to supply it. Perfect, thank you!

 

 

No i think your still not getting your head around it, The regulator is just an adjustable restriction, its always open, its just a restriction, and the result of a restriction is pressure, so the circuit goes......fuel tank-fuel pump-fuel filter-fuel rail/injectors- fuel regulator, and from there back to the tank.

 

Question for the OP, so presumably your FI, so depending on the power output, have you fitted an uprated fuel pump?

From what i remember there is a fuel filter and the pulsation damper in the std setup, IMO it would probably be better to dump the pulsation damper, as i am not sure how its going to affect the things with an uprated fuel flow.

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No i think your still not getting your head around it, The regulator is just an adjustable restriction, its always open, its just a restriction, and the result of a restriction is pressure, so the circuit goes......fuel tank-fuel pump-fuel filter-fuel rail/injectors- fuel regulator, and from there back to the tank.

Ah, fixed orifice, gotcha.

 

So what happens in that system if you don't have a regulator? Pressure is determined by the fuel pump alone, I assume? Well, along with the natural restriction present in the pipework itself.

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No i think your still not getting your head around it, The regulator is just an adjustable restriction, its always open, its just a restriction, and the result of a restriction is pressure, so the circuit goes......fuel tank-fuel pump-fuel filter-fuel rail/injectors- fuel regulator, and from there back to the tank.

Ah, fixed orifice, gotcha.

 

So what happens in that system if you don't have a regulator? Pressure is determined by the fuel pump alone, I assume? Well, along with the natural restriction present in the pipework itself.

No i think your still not getting your head around it, The regulator is just an adjustable restriction, its always open, its just a restriction, and the result of a restriction is pressure, so the circuit goes......fuel tank-fuel pump-fuel filter-fuel rail/injectors- fuel regulator, and from there back to the tank.

Ah, fixed orifice, gotcha.

 

So what happens in that system if you don't have a regulator? Pressure is determined by the fuel pump alone, I assume? Well, along with the natural restriction present in the pipework itself.

 

You need a regulator to rise fuel pressure with boost on FI engines. You dont need an adjustable one but that's an easy way to get a gauge so you can check pressure and upping the fuel pressure can help you flow more fuel through a smaller injector meaning you dont need to fit bigger ones

 

As you say in many cases the fuel pressure is set by a fixed orofice in the pipework itself

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Yeah as i understand the system on the Z, the pump is ECU controlled so the pump motor is speeded up/slowed down, keeping the fuel pressure within it required boundaries depending on engine load, which in effect makes it the regulator as there is no return, i would suspect that the ECU fuel pump control can be accessed and adjusted, but i dont remember seeing it in the Uprev software, maybe Mark or Jez could supply the answer to that one.

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No i think your still not getting your head around it, The regulator is just an adjustable restriction, its always open, its just a restriction, and the result of a restriction is pressure, so the circuit goes......fuel tank-fuel pump-fuel filter-fuel rail/injectors- fuel regulator, and from there back to the tank.

Ah, fixed orifice, gotcha.

 

So what happens in that system if you don't have a regulator? Pressure is determined by the fuel pump alone, I assume? Well, along with the natural restriction present in the pipework itself.

No i think your still not getting your head around it, The regulator is just an adjustable restriction, its always open, its just a restriction, and the result of a restriction is pressure, so the circuit goes......fuel tank-fuel pump-fuel filter-fuel rail/injectors- fuel regulator, and from there back to the tank.

Ah, fixed orifice, gotcha.

 

So what happens in that system if you don't have a regulator? Pressure is determined by the fuel pump alone, I assume? Well, along with the natural restriction present in the pipework itself.

 

You need a regulator to rise fuel pressure with boost on FI engines. You dont need an adjustable one but that's an easy way to get a gauge so you can check pressure and upping the fuel pressure can help you flow more fuel through a smaller injector meaning you dont need to fit bigger ones

 

As you say in many cases the fuel pressure is set by a fixed orofice in the pipework itself

 

 

Sorry but fuel pressure needs to be set to suit the injectors used, some require different base fuel pressure, so adjustable is needed,

 

Also using higher fuel pressure to increase the flow rate of an injector is bad practice in my book, its OK for maybe a stop gap for a small power increase, but you will loose the headroom of the injector,

Injectors should not use more than 85% of there duty cycle, so should be sized to take required power output at 85% of there duty cycle, which leaves some headroom should the ECU need to increase fueling suddenly if det or denser airflow is detected.

 

It also helps prevent failure of the injector coil.

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No i think your still not getting your head around it, The regulator is just an adjustable restriction, its always open, its just a restriction, and the result of a restriction is pressure, so the circuit goes......fuel tank-fuel pump-fuel filter-fuel rail/injectors- fuel regulator, and from there back to the tank.

Ah, fixed orifice, gotcha.

 

So what happens in that system if you don't have a regulator? Pressure is determined by the fuel pump alone, I assume? Well, along with the natural restriction present in the pipework itself.

No i think your still not getting your head around it, The regulator is just an adjustable restriction, its always open, its just a restriction, and the result of a restriction is pressure, so the circuit goes......fuel tank-fuel pump-fuel filter-fuel rail/injectors- fuel regulator, and from there back to the tank.

Ah, fixed orifice, gotcha.

 

So what happens in that system if you don't have a regulator? Pressure is determined by the fuel pump alone, I assume? Well, along with the natural restriction present in the pipework itself.

 

You need a regulator to rise fuel pressure with boost on FI engines. You dont need an adjustable one but that's an easy way to get a gauge so you can check pressure and upping the fuel pressure can help you flow more fuel through a smaller injector meaning you dont need to fit bigger ones

 

As you say in many cases the fuel pressure is set by a fixed orofice in the pipework itself

 

 

Sorry but fuel pressure needs to be set to suit the injectors used, some require different base fuel pressure, so adjustable is needed,

 

Also using higher fuel pressure to increase the flow rate of an injector is bad practice in my book, its OK for maybe a stop gap for a small power increase, but you will loose the headroom of the injector,

Injectors should not use more than 85% of there duty cycle, so should be sized to take required power output at 85% of there duty cycle, which leaves some headroom should the ECU need to increase fueling suddenly if det or denser airflow is detected.

 

It also helps prevent failure of the injector coil.

 

I agree that upping base pressure isnt recommended however its a very common route albeit less common nowadays, I've never needed to fit an adjustable reg on any of my modified turbo cars

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Okay, that makes a bit more sense now. I assumed the excess was dumped back to the tank, which is why I was getting a bit confused.

 

I assume the regulator isn't put before the injectors simply so you don't end up in a situation where you get a massive need for fuel and the regulator can't open quickly enough to supply it. Perfect, thank you!

 

 

No i think your still not getting your head around it, The regulator is just an adjustable restriction, its always open, its just a restriction, and the result of a restriction is pressure, so the circuit goes......fuel tank-fuel pump-fuel filter-fuel rail/injectors- fuel regulator, and from there back to the tank.

 

Question for the OP, so presumably your FI, so depending on the power output, have you fitted an uprated fuel pump?

From what i remember there is a fuel filter and the pulsation damper in the std setup, IMO it would probably be better to dump the pulsation damper, as i am not sure how its going to affect the things with an uprated fuel flow.

Yeh this is all part of going FI, The fuel pump has been replaced with a walbro 255lph.

I'll need to keep the dampener for just now as i'd have to source a blanking plate to go on the end of my adapter. I'll keep it in mind and mention it to the guys when it comes to tuning it if they are having fueling issues.

 

Massive help guys thanks, helping me push on with this build. Never supercharged a car before so its one big learning curve. I'm sure there will be more questions over the next few days regarding building to boost.

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