FPR positioning...
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It should be after the fuel rail mate.
I guess you could go before BUT you would be depending on the return line pressure so the fpr would need to allow more fuel to pass in order to increase flow/pressure to the injectors when boost pressure increases and that would probably mean the reg would need to work backwards ie, falling rate..
Why not just keep things simple and use it as it was designed, go after the rail buddy.
Its sorta like using a blow off valve as a boost regulator instead of a wastegate..
I guess you could go before BUT you would be depending on the return line pressure so the fpr would need to allow more fuel to pass in order to increase flow/pressure to the injectors when boost pressure increases and that would probably mean the reg would need to work backwards ie, falling rate..
Why not just keep things simple and use it as it was designed, go after the rail buddy.
Its sorta like using a blow off valve as a boost regulator instead of a wastegate..
3zercrowd
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Which option would you think causes the least disturbance to the flow of fuel into the fuel rail to the injectors?:
1. Fuel exiting the FPR via the return line BEFORE the fuel rail; or
2. Fuel exiting the FPR via the return line AFTER the fuel rail.
Makes sense doesnt it :thumbsup:
1. Fuel exiting the FPR via the return line BEFORE the fuel rail; or
2. Fuel exiting the FPR via the return line AFTER the fuel rail.
Makes sense doesnt it :thumbsup:
If you are using the fuel exiting the fuel pressure reg to feed the injectors, wouldn't you have extremely low pressure at the injectors and almost no control of fuel pressure? You'd be depending on a restriction on the return line to provide pressure and in that case, no control..
Thats right Baz. I hope nobody uses the return line to fuel injectors, where did it mention that?
The fuel system flow is simple. Fuel tank, to fuel pump, to fuel filter, to fuel rail, to FPR, to return line, to fuel tank.
The fuel system flow is simple. Fuel tank, to fuel pump, to fuel filter, to fuel rail, to FPR, to return line, to fuel tank.
Thats right,
This is asking if the FPR should be placed before or after the rail.
I think there is a bit of confusion in to what the question is actually about and also what the setup is meant to be.
I think having the fpr on the surge tank doesn't indicate that it is before the fuel rail but rather at the return line so all in all, it is the same regardless (after the fuel rail).
This is asking if the FPR should be placed before or after the rail.
I think there is a bit of confusion in to what the question is actually about and also what the setup is meant to be.
I think having the fpr on the surge tank doesn't indicate that it is before the fuel rail but rather at the return line so all in all, it is the same regardless (after the fuel rail).
Yes baz and rob are both right.
***DON'T EVER PUT AN FPR BEFORE THE FUEL RAIL- EVER***
FPR'S hold pressure at the rail by restricting (choking flow) more or less. There will be a large pressure drop across the fpr at high rail pressures (at peak flow in the system the pressure will be almost atmospheric downstream i.e. zero gauge, of the rail). Putting the fpr before the rail will give you some flow with no pressure at the rail=> i.e. a fucking disaster!
Please show me anything to the contrary.
***DON'T EVER PUT AN FPR BEFORE THE FUEL RAIL- EVER***
FPR'S hold pressure at the rail by restricting (choking flow) more or less. There will be a large pressure drop across the fpr at high rail pressures (at peak flow in the system the pressure will be almost atmospheric downstream i.e. zero gauge, of the rail). Putting the fpr before the rail will give you some flow with no pressure at the rail=> i.e. a fucking disaster!
Please show me anything to the contrary.
I'm sure I replied to this thread just after it was posted up but my post has dissapeared?
Anyway, most new cars use a system where the fuel pressure reg is built into the fuel pump assy so therefore it is before the fuel rail.
I think you could have the fuel pressure reg just before the rail but you would have to have it "T"ed into the line so the fuel returns to the tank in the normal way just the reg is situated before the rail, there will be a down side of not much flow through the rail so you could get a slight buildup but as I mentioned modern systems don't return fuel to the tank at all.
Anyway, most new cars use a system where the fuel pressure reg is built into the fuel pump assy so therefore it is before the fuel rail.
I think you could have the fuel pressure reg just before the rail but you would have to have it "T"ed into the line so the fuel returns to the tank in the normal way just the reg is situated before the rail, there will be a down side of not much flow through the rail so you could get a slight buildup but as I mentioned modern systems don't return fuel to the tank at all.
Richard said:
You don't understand how fpr's IN OUR CARS work. Fpr's like OEM, sard, aeromotive etc cause pressure drop - This maintains upstream pressure at the rail by throttling flow. How do you INCREASE fuel pressure at the rail if the fpr is before it. All TEEing does is decrease the flow to the rail. Why the hell would you do that?
Modern systems are designed and controlled differently with closed systems - you can't compare them.
rob323
Don't drive it, RALLY it!
My Echo has the fpr built into the pump housing and does not have a fuel return line, and as it has no reference to intake manifold pressure or vacuum, it provides a constants fuel pressure irrespective of load.
But, I cannot see how a system like this can be used for a boosted situation as you have no way to adjust fuel pressure in relation to boost pressure.
How to do the current turbo'd VW, Saabs etc do it? Do they still just use a normal return line setup, or do they run a sufficiently high enough fuel pressure to cover when they are "on boost" and just have great control over the injectors at idle and cruise loads?
But, I cannot see how a system like this can be used for a boosted situation as you have no way to adjust fuel pressure in relation to boost pressure.
How to do the current turbo'd VW, Saabs etc do it? Do they still just use a normal return line setup, or do they run a sufficiently high enough fuel pressure to cover when they are "on boost" and just have great control over the injectors at idle and cruise loads?
Subaru's still have a return line for there boosted models, not sure on other makes, but overall they do have a much higher running fuel pressure than our older cars.
Modern returnless systems that maintain a constant fuel pressure via a spring reg at the pump have very extencive maps in the ECU to control the injectors rather than alter fuel pressure with manifold vacuum which makes the maps much simpler.
Modern returnless systems that maintain a constant fuel pressure via a spring reg at the pump have very extencive maps in the ECU to control the injectors rather than alter fuel pressure with manifold vacuum which makes the maps much simpler.
rob323
Don't drive it, RALLY it!
Nah it won't work for the simple reason 4G63's have 4 injectors. not 3Richard said:
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