AMS Ultimate Fuel Pump Test
Apr 6, 2007, 05:46 PM
#32
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Only issue with running two pumps into a Y-fitting is that the pump with the strongest pressure will flow through the fitting effectively putting the lesser pump in a no-flow condition. Parallel configuration would seem to be the most benificial due to reasons you've already stated.
Last edited by Cirrusly Evolvd; Apr 6, 2007 at 05:49 PM.
Apr 6, 2007, 07:12 PM
#33
The AMS Evo fuel system uses an in-tank Walbro 255 and an external Walbro 392 (in-line 255), connected together with a "Y" fitting to the -8AN feed line to the front of the car...
Apr 6, 2007, 07:26 PM
#35
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What data do you have to support this conclusion? That's the point of testing, to determine if the higher capacity pump affects the lower capacity pump flow or not...
The AMS Evo fuel system uses an in-tank Walbro 255 and an external Walbro 392 (in-line 255), connected together with a "Y" fitting to the -8AN feed line to the front of the car...
The AMS Evo fuel system uses an in-tank Walbro 255 and an external Walbro 392 (in-line 255), connected together with a "Y" fitting to the -8AN feed line to the front of the car...
Apr 6, 2007, 07:55 PM
#37
I'm sure you'll agree that actual testing would be a more precise method of demonstrating the exact effect of swapping a larger pump for the Walbro 392 that is in the AMS system now. Then we'll have specific data that will make both of us happy. I'll be happy to know what the outcome is, and you can say "See, I told you so..."
Apr 6, 2007, 08:03 PM
#38
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LOL...well I'm only an *** on Sunday's but ok. But what I say is correct. On C-130's (the planes I fly on) we have two types of fuel pumps. One style has an out put of 28-40 psi (dependent on load) and the other style is 14-20. All of our fuel cells are connected by a single manifold therefore any pump can supply pressure to any engine. However if you have two pumps pushing fuel to the same engine manifold (very similar to autos) the one with the highest pressure will supply the fuel to the engine. Even if both pumps are rated the same, they can differ fby a couple psi and the larger one will win. Its more or less hydraulic theory but there is a scientific principle name for this and I forget it at this moment.
Apr 6, 2007, 09:34 PM
#39
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LOL...well I'm only an *** on Sunday's but ok. But what I say is correct. On C-130's (the planes I fly on) we have two types of fuel pumps. One style has an out put of 28-40 psi (dependent on load) and the other style is 14-20. All of our fuel cells are connected by a single manifold therefore any pump can supply pressure to any engine. However if you have two pumps pushing fuel to the same engine manifold (very similar to autos) the one with the highest pressure will supply the fuel to the engine. Even if both pumps are rated the same, they can differ fby a couple psi and the larger one will win. Its more or less hydraulic theory but there is a scientific principle name for this and I forget it at this moment.
Apr 6, 2007, 09:43 PM
#40
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Ok, well you can disagree all you want. My experience is coming from Lockheed Martin...(just in case you don't know, they've designed/built military airplanes for over 60 years including their fuel pumps/systems). I'm sure your 4 year degree beats that...
But anyways, you just backed up what I was saying. If you have two pumps supplying the exact same pressure to the same manifold then yes your statement is correct. However I highly doubt you will find two pumps that will flow the EXACT same. Therefore in a parallel configuration the pump with the most pressure will be supplying the manifold. What is being used is of no consequence unless the draw is greater than the pumps ability to flow. When that pump's output decreases below the other, then the other pump will be supplying the flow. It's simple hydro-dynamics. Put that degree to use and look it up.
But anyways, you just backed up what I was saying. If you have two pumps supplying the exact same pressure to the same manifold then yes your statement is correct. However I highly doubt you will find two pumps that will flow the EXACT same. Therefore in a parallel configuration the pump with the most pressure will be supplying the manifold. What is being used is of no consequence unless the draw is greater than the pumps ability to flow. When that pump's output decreases below the other, then the other pump will be supplying the flow. It's simple hydro-dynamics. Put that degree to use and look it up.
Last edited by Cirrusly Evolvd; Apr 6, 2007 at 09:53 PM.
Apr 6, 2007, 09:50 PM
#41
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Do you agree all fluids flow from high pressure to low pressure? If so, how can you disagree with the statement I made? The only way your scenario of one pump overriding the other is true is if the combined flow creates such a large pressure drop in the lines that the pump discharge pressures are way off from what the fuel pressure regulator is trying to control at. In that case, I'd say all them C130's you been working on have too small of fuel lines.
Apr 6, 2007, 09:56 PM
#42
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Maybe we should call Mythbusters and have them do the testing with clear hoses and colored fluids........
Vote Martin for Wookiee of the year!!
Vote Martin for Wookiee of the year!!
Last edited by EricJ@AMS; Apr 6, 2007 at 10:00 PM.
Apr 6, 2007, 09:58 PM
#43
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Ok, well you can disagree all you want. My experience is coming from Lockheed Martin...(just in case you don't know, they've designed/built military airplanes for over 60 years including their fuel pumps/systems). I'm sure your 4 year degree beats that...
But anyways, you just backed up what I was saying. If you have two pumps supplying the exact same pressure to the same manifold then yes your statement is correct. However I highly doubt you will find two pumps that will flow the EXACT same. Therefore in a parallel configuration the pump with the most pressure will be supplying the manifold. What is being used is of no consequence unless the draw is greater than the pumps ability to flow. When that pump's output decreases below the other, then the other pump will be supplying the flow. It's simple hydro-dynamics. Put that degree to use and look it up.
But anyways, you just backed up what I was saying. If you have two pumps supplying the exact same pressure to the same manifold then yes your statement is correct. However I highly doubt you will find two pumps that will flow the EXACT same. Therefore in a parallel configuration the pump with the most pressure will be supplying the manifold. What is being used is of no consequence unless the draw is greater than the pumps ability to flow. When that pump's output decreases below the other, then the other pump will be supplying the flow. It's simple hydro-dynamics. Put that degree to use and look it up.
late addition: I don't have to look it up, I know.
Last edited by dubbleugly01; Apr 6, 2007 at 09:58 PM. Reason: forgot to add a point.....
Apr 6, 2007, 10:02 PM
#44
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not trying to trump, just rationally discuss.
Do you agree all fluids flow from high pressure to low pressure? If so, how can you disagree with the statement I made? The only way your scenario of one pump overriding the other is true is if the combined flow creates such a large pressure drop in the lines that the pump discharge pressures are way off from what the fuel pressure regulator is trying to control at. In that case, I'd say all them C130's you been working on have too small of fuel lines.
Do you agree all fluids flow from high pressure to low pressure? If so, how can you disagree with the statement I made? The only way your scenario of one pump overriding the other is true is if the combined flow creates such a large pressure drop in the lines that the pump discharge pressures are way off from what the fuel pressure regulator is trying to control at. In that case, I'd say all them C130's you been working on have too small of fuel lines.
Late edition too: If you have to forces pushing in the same direction of a confined space who will win? 40 psi against 39 psi....hmm, 40 psi will win so it gets the flow. Don't bother arguing your point, because you are wrong.
Apr 6, 2007, 10:09 PM
#45
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I had revised my prior statement. And size of fuel line is no difference. 40 psi is 40 psi, no matter how big or small the lines are. (In fact, C-130 fuel lines are about an inch in diameter coming from the tanks and half an inch going into the engine) I'm sorry but I just don't have books on hydro-dynamics laying around to fully explain it to you. What I do have is over a decade of experience with multiple aircraft and their fuel systems which tell me how pumps and manifolds work. Sorry you can't be satisfied with that.
Not to get in a pissing contest and ruin this thread, can we agree that there can only be one pressure at the tee? Both pumps will be pumping against the same backpressure, therefore they'll be putting up the same pressure. It ain't rocket science
