EFI Fuel Pump Flow Rating?

I have a (couple of) questions about fuel pump flow rating.

I see most of the Walbro pumps are rated at 255ltr/hr (67gal/hr). 67 gallons multiplied by 6.34 lbs. (weight of a gallon of gasoline) is 427 lbs. So the 255ltr/hr pumps flow 427 lbs of fuel in one hour. If you are making 500hp @ .5 BSFC, you will need ~40lbs/hr injectors. 40 x 8=320lbs/hr and you need some headroom there, so I'm guessing you want 350lbs/hr +. All of this at 43.5psi presumably.

Is this correct? What is the pupose of converting gallons to lbs?

So, when you see the flow ratings of these pumps are they rating the flow at 43.5psi?



.

Looks like the walbro pumps are rated @ 20 psi.

Fuel pump flow rates and current draw at 12 volts

[tr][td]Pressure (psi)[/td][td]190 ltr/hr fuel pump (gal/hr)[/td][td]190 ltr/hr fuel pump (amps)[/td][td]"high pressure" 190 ltr/hr pump (gal/hr)[/td][td]"high pressure" 190 ltr/hr pump (amps)[/td][td]255 ltr/hr fuel pump (gal/hr)[/td][td]255 ltr/hr fuel pump (amps)[/td][td]"high pressure" 255 ltr/hr pump (gal/hr)[/td][td]"high pressure" 255 ltr/hr pump (amps)[/td][/tr][tr][td]0[/td][td]56[/td][td]2.6[/td][td]53[/td][td]2.8[/td][td]75[/td][td]4.7[/td][td]76[/td][td]4.4[/td][/tr][tr][td]10[/td][td]52[/td][td]3.2[/td][td]50[/td][td]3.5[/td][td]72[/td][td]5.2[/td][td]73[/td][td]4.8[/td][/tr][tr][td]20[/td][td]48[/td][td]4.0[/td][td]48[/td][td]4.3[/td][td]67[/td][td]6.1[/td][td]68[/td][td]5.5[/td][/tr][tr][td]30[/td][td]44[/td][td]4.8[/td][td]44[/td][td]5.0[/td][td]62[/td][td]7.2[/td][td]63[/td][td]6.3[/td][/tr][tr][td]40[/td][td]40[/td][td]5.7[/td][td]41[/td][td]5.9[/td][td]58[/td][td]8.2[/td][td]59[/td][td]7.1[/td][/tr][tr][td]50[/td][td]36[/td][td]6.6[/td][td]38[/td][td]6.8[/td][td]53[/td][td]9.3[/td][td]54[/td][td]8.0[/td][/tr][tr][td]60[/td][td]32[/td][td]7.6[/td][td]35[/td][td]7.8[/td][td]49[/td][td]10.6[/td][td]51[/td][td]8.9[/td][/tr][tr][td]70[/td][td]28[/td][td]8.6[/td][td]31[/td][td]8.8[/td][td]40[/td][td]11.8[/td][td]46[/td][td]9.9[/td][/tr][tr][td]80[/td][td]22[/td][td]9.7[/td][td]29[/td][td]9.9[/td][td]29[/td][td]13.3[/td][td]41[/td][td]11.0[/td][/tr][tr][td]90[/td][td]12[/td][td]10.8[/td][td]25[/td][td]10.9[/td][td]0[/td][td]14.6[/td][td]32[/td][td]12.0[/td][/tr][tr][td]100[/td][td]0[/td][td]12.5[/td][td]21[/td][td]12.0[/td][td]---[/td][td]---[/td][td]22[/td][td]13.2[/td][/tr][tr][td]110[/td][td]---[/td][td]---[/td][td]17[/td][td]13.5[/td][td]---[/td][td]---[/td][td]11[/td][td]14.5[/td][/tr][tr][td]120[/td][td]---[/td][td]---[/td][td]11[/td][td]15.0[/td][td]---[/td][td]---[/td][td]1[/td][td]15.8[/td][/tr]

I wish I knew the answer to your question but I don't. I am running a Walbro in-tank pump. Using a 3/8" fuel line and an adjustable fuel pressure regulator I am running 43 lbs pressure at idle on the fuel rail of the TPI on a small block. I can adjust it higher but I don't need to. I am running 22lb Bosch injectors.

I also have an external Walbro pump as a redundant fuel pump and the fuel pressure runs the same if I use the external pump.

I do not (and have not tried to) run both pumps at the same time. I guess I could but that is not the purpose of the back up system. The external is there in case of in-tank pump failure.

I don't know if this helps but I hope so.

Rich:drink:

Fuel pump flow rates and current draw at 13.5 volts

[tr][td]Pressure (psi)[/td][td]190 ltr/hr fuel pump (gal/hr)[/td][td]190 ltr/hr fuel pump (amps)[/td][td]"high pressure" 190 ltr/hr pump (gal/hr)[/td][td]"high pressure" 190 ltr/hr pump (amps)[/td][td]255 ltr/hr fuel pump (gal/hr)[/td][td]255 ltr/hr fuel pump (amps)[/td] [td]"high pressure" 255 ltr/hr pump (gal/hr)[/td][td]"high pressure" 255 ltr/hr pump (amps)[/td][/tr][tr][td]0[/td][td]63[/td][td]3.1[/td][td]60[/td][td]3.3[/td][td]82[/td][td]5.2[/td][td]85[/td][td]5.0[/td][/tr][tr][td]10[/td][td]61[/td][td]3.5[/td][td]58[/td][td]3.9[/td][td]81[/td][td]5.9[/td][td]82[/td][td]5.2[/td][/tr][tr][td]20[/td][td]57[/td][td]4.2[/td][td]56[/td][td]4.5[/td][td]76[/td][td]6.5[/td][td]79[/td][td]6.0[/td][/tr][tr][td]30[/td][td]52[/td][td]5.0[/td][td]52[/td][td]5.3[/td][td]71[/td][td]7.8[/td][td]73[/td][td]6.8[/td][/tr][tr][td]40[/td][td]49[/td][td]5.8[/td][td]50[/td][td]6.2[/td][td]68[/td][td]8.6[/td][td]70[/td][td]7.5[/td][/tr][tr][td]50[/td][td]46[/td][td]6.6[/td][td]47[/td][td]7.2[/td][td]62[/td][td]9.8[/td][td]65[/td][td]8.2[/td][/tr][tr][td]60[/td][td]42[/td][td]7.5[/td][td]45[/td][td]8.0[/td][td]58[/td][td]10.8[/td][td]61[/td][td]9.1[/td][/tr][tr][td]70[/td][td]38[/td][td]8.4[/td][td]41[/td][td]8.8[/td][td]50[/td][td]12.0[/td][td]56[/td][td]10.2[/td][/tr][tr][td]80[/td][td]32[/td][td]9.4[/td][td]38[/td][td]9.8[/td][td]39[/td][td]13.3[/td][td]51[/td][td]11.1[/td][/tr][tr][td]90[/td][td]22[/td][td]10.3[/td][td]34[/td][td]10.9[/td][td]11[/td][td]14.4[/td][td]43[/td][td]12.1[/td][/tr][tr][td]100[/td][td]14[/td][td]11.5[/td][td]31[/td][td]12.0[/td][td]1[/td][td]15.0[/td][td]32[/td][td]13.2[/td][/tr][tr][td]110[/td][td]---[/td][td]12.7[/td][td]28[/td][td]13.2[/td][td]---[/td][td]---[/td][td]20[/td][td]14.3[/td][/tr][tr][td]120[/td][td]---[/td][td]---[/td][td]22[/td][td]14.5[/td][td]---[/td][td]---[/td][td]11[/td][td]15.7[/td][/tr][tr][td]130[/td][td]---[/td][td]---[/td][td]18[/td][td]16.0[/td][td]---[/td][td]---[/td][td]---[/td][td]17.0[/td][/tr]

The pounds/hr rating btw is a result of the calculations used for stoichiometric requirements. Mass air or speed density give an air mass value not a volume (since volume is dep. on temp, humidity, altitude....). This way it's always calculated in mass and therefore you don't need a correction factor.

Twin_Turbo said:

The pounds/hr rating btw is a result of the calculations used for stoichiometric requirements. Mass air or speed density give an air mass value not a volume (since volume is dep. on temp, humidity, altitude....). This way it's always calculated in mass and therefore you don't need a correction factor.

Click to expand...

It still seems like a convoluted calculation method:bonkers:. Injectors are listed in mass flow, pumps are listed in volume and on top of that liters are converted to pounds.

BBShark said:

Twin_Turbo said:

The pounds/hr rating btw is a result of the calculations used for stoichiometric requirements. Mass air or speed density give an air mass value not a volume (since volume is dep. on temp, humidity, altitude....). This way it's always calculated in mass and therefore you don't need a correction factor.

Click to expand...

It still seems like a convoluted calculation method:bonkers:. Injectors are listed in mass flow, pumps are listed in volume and on top of that liters are converted to pounds.

Click to expand...

I just took the advice of the injector sites....24 lbs is supporting a max of 375-400 hp at any reasonable pressure....40 psi+++

want 800 hp....48 lbs injectors....gotta be, I"d suppose....

:bonkers: