Fuel pumps gph and PSI

Engines, Exhaust and Fuel Systems

  1. Bruceynz

    Bruceynz Well-Known Member

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    Hello,

    I have a Holley 97gph fuel pump, I hate it! It's so loud in the back! It's got more whine than the opposition party! Sounds like Concorde coming in to land!

    I see on eBay there are some 3.5 - 5 psi 42gph and some 4-7 psi 30gph.

    It says on net rule of thumb 10hp x gph so our 30gph is good for 300hp, really?

    What can I get away with to feed my mild 360?

    Will a 600 Holley run ok on 3.5 - 5 psi?

    Thank
    Bruce
     
  2. Oldiron440

    Oldiron440 Well-Known Member

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    I would like more that 3 to 5 psi, what carb do you have?
     
  3. Bruceynz

    Bruceynz Well-Known Member

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    600 Holley vac secondaries
     
  4. Bruceynz

    Bruceynz Well-Known Member

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    Ok, I am sick of the holley pump, its never caused any issues, I am not doubting its a good pump but it sure is one noisy pump, sounds like a a swarm of locus is in the trunk! Today I bought one of these, I see Holley says 32gph should support 400hp, since I am not near 400hp I figure the quietness will be worth it.

    Black Polymer 12S Electric Fuel Pump 35gph/132lph 4-7 PSI 5/16 in Gasoline

    s-l1600.jpg
     
    Last edited: Jul 30, 2019
  5. volare 77

    volare 77 Well-Known Member

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    Yea, i ran a holley pump when i was much younger. I didn`t like the sound even back then. One thing is you always knew when it was running. LOL
     
  6. Duke5A

    Duke5A Well-Known Member

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    Why the electric at all? I'm fairly certain you can get a fuel pump eccentric for a Magnum motor and use a standard LA timing cover.

    The best electric setup though is an in-tank pump.
     
  7. Bruceynz

    Bruceynz Well-Known Member

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    Hi,

    I don't have a LA cover, I don't have an eccentric cam drive, and as the car sits for a while the electric seems to get the fuel from the back to the front better.

    When it had the old 318 LA engine in it with the mech pump if you didn't tip a cap full of gas down the carb to get that we pump stroking flat out you could be in for a fair bit of cranking! Which is hard on starter, hard on wires, hard on battery! Electric just whizzes the bowels full and 2nd crank your running, if using on daily basis mech pump fine.

    Thanks
    Bruce
     
  8. Duke5A

    Duke5A Well-Known Member

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    Well, the pump that came with my Sniper EFI setup is an external and it is really damn quiet for what it is. Actually can't hear in or out of the car. If you were to run it you would need a regulator.
     
  9. Bruceynz

    Bruceynz Well-Known Member

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    Holley red 97gph are noisy as! I stop at the traffic lights and sounds like a swarm of bees have joined me in the back seat!!!
     
  10. Bruceynz

    Bruceynz Well-Known Member

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    A picture tells a 1000 words

    upload_2019-7-31_10-47-44.png
     
    Duke5A likes this.
  11. Oldiron440

    Oldiron440 Well-Known Member

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    I could never here mine run, after the car fired.:) And I had the blue pump.
     
  12. Bruceynz

    Bruceynz Well-Known Member

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    upload_2019-7-31_11-39-6.png
     
  13. Oldiron440

    Oldiron440 Well-Known Member

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    The sound of a fuel pump has never been a problem for me, what was a problem was not having the volume of fuel I needed and blue pump didn't cut it. So what's a little noise?
     
  14. Aspen500

    Aspen500 Well-Known Member

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    What is fine on a race car, like fuel pump noise, will drive you insane on a street car.

    In tank is best for many reasons. Noise is one of them. I remember back in the 1980's, some Ford trucks had a low pressure lift pump in the tank(s) and a high pressure pump on the frame rail. I wonder what type of pump those were because you could barely hear them run, even if you were under the truck a foot away from it. Nothing but a soft "whir".
     
  15. Oldiron440

    Oldiron440 Well-Known Member

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    It was a street car back then, here's what I'm going to be using on my 289.
    Quick Fuel Electric Fuel Pumps 30-175QFT
    It gets a return fuel regulator set up. That's a 1/2" line to and from the carb.
     
  16. Bruceynz

    Bruceynz Well-Known Member

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    rule of thumb GPH x 10 = aprox HP 175GPH good for 1750hp! she sure is a power house!
     
  17. Oldiron440

    Oldiron440 Well-Known Member

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    I don't know where you get your formula but this is a return fuel system. The fuel goes the the carb then the regulator bleeds fuel pressure for the carb then sends the excess back to the tank. This is the most consistent way to deliver fuel at a certain presser to the carb. You have the max volume at the carb under all conditions. Quick Fuel said this is what I needed and if I go turbo or supercharged it will need the next larger size.
    At 300 hp it probably won't take much of a fuel pump to keep your car running down the road.
    I know the blue pump couldn't supply my 440 for a 1000 feet under full throttle and that was only 500 hp.
     
  18. Bruceynz

    Bruceynz Well-Known Member

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    Choosing the Correct Fuel Pump
    Different fuel pump manufacturers rate their fuel pumps in different ways. Some manufacturers for instance rate their fuel pumps at free flow. The problem with this rating is that no fuel system operates at zero psi. Other fuel pump companies may rate their fuel pumps at a given psi. For example the Walbro fuel pumps that we sell are rated at 40 psi. Our most popular fuel pump we sell is the 4 series fuel pump assembly. These assemblies use a Walbro 255 lph fuel pump. 255 liters is the volume of fuel that the pump will flow at 40 psi. While this is a more accurate rating than a free flow rating, the 255 lph rating is only accurate if you are running your engine at 40 psi and your pump is being supplied with 13 volts.

    Sometimes pumps are rated based on pressure. For example the Walbro 255 lph pump is capable of producing a pressure in excess of 100 psi. While this information may be relevant, it only provides one detail about a fuel pumps capability.

    The better way to select a fuel pump to use in your fuel system is to consider three factors:

    1. How much horsepower your engine will produce.
    2. What fuel pressure is required for your engine.
    3. How much voltage is supplied to your fuel pump when the engine is running.
    1. Horsepower

    The amount of horsepower that your engine has will determine how much fuel flow is required to support that engine. As horsepower increases so does the volume of fuel required to support that power. A good estimator of volume to power is approximately 10 hp per gallon or 2.64 hp per liter. For example if your pump flows at 50 gph it should be able to support a 500 hp engine (50 x 10 = 500). However, to actually know the gph you must also consider the fuel pressure required for your engine.


    Choosing the Correct Fuel Pump
     
  19. Oldiron440

    Oldiron440 Well-Known Member

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    "An estimated A good estimator of volume to power is approximately 10 hp per gallon or 2.64 hp per liter."

    That may be an estimate but real world is there are two many Variables that make a statement like this true.
    As it says there are differences in how different punps are rated also you need to consider the size of you fuel line, number of bends in the line and filter. Òn a race car you need to push fuel against inertia. If it's a drag or street car that launches hard the pump needs to over power the fuel trying to go back to the tank just to feed the carb. On a car that's going around corners there additional loads on the fuel pump. On my 440s in the Volare the Holley blue pump couldn't supply enough fuel and the car has 1/2" fuel line with very few bends in it.
    Now the 440s I have, have never been easy on fuel, one eighth mile pass could use a gallon + of fuel. My 500" used a full 5 gallons of fuel to break in the cam and make 4 pulls on the dyno. That's 650 hp for you.
    The statement at the top can only be true for there fuel pumps in whatever parameters they set.

    The last self regulated fuel pump I used other than using it as a way to fill my tank from a drum was on a smoggler 440 375hp or so. A regulator at the carb would have been better. On a good day on the hyway it would get 7 miles per gallon.
     
    Last edited: Aug 4, 2019
  20. SixBanger

    SixBanger Well-Known Member

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    7 miles a galon? Need big holes in the gastank to get no vacuum when accerate?? Thing is thirsty!