Fuel Pumps

[Bill Musarra]

In looking at fuel pumps, how does one compare lbs. per hour and gal. per hour. I am trying to figure out the low pressure pump to the sump and the high pressure pump to the injectors. The high pressure ones are rated in lbs. per hour. ex. "Flows over 450 lbs. per hour @12 volts and 45 psi". The low pressure pumps are,"maximum pressure in psi" from 2.5 to 7.5 typically. with a flow of 15 to 35 gals./hr. at 1 to 2 psi. with max gals/hr of 28to 45.(small pumps). I assume that is unrestricted flow. I am currently looking at the Holley blue pump with max flow of 110gph for the low pressure side, and the Aeromotive for the high pressure side. Is the low side overkill and a waste of money?
It is a little confusing to me. I don't want the high pressure pump ever to starve, although I don't think it will with the return line from the injectors to the sump, and an overflow back to the tank. I am just trying to be careful. Any help would be appreciated.

Bill

 

[Chris Duncan]

I knew it was close to 6 but Google sez one pound of gas weighs about 6.25 lbs

So 450 lbs / 6.25 = 72 gal

I'm guessing the lbs per hr spec is a more accurate way of measuring flow because of the different viscosities/densities of different fuels.

Your engine is never going to use more fuel than the low pressure, lower gph pump is capable of supplying so the high pressure pump is never going to need more than that, so will never starve.

 

[Paul Thompson 'Hooligan']

Hi Bill

Rekon on consumption of approx 5cc per minute per HP,
so 110 gals / hour = approx 416L / hour = 6.9L per min = 1300+ HP

So, as Kalun says, if your Lp pump flows 110 gals / hour, you won't run dry unless your motor is producing more than 1300 HP -

If you return the HP fuel (via reg) back to the swirl pot (sump), then the LP pump need ONLY flow enough to cover the absolute maximum expected power output of the motor.

If you return the HP fuel to a main tank, then the LP pump must flow MORE than the HP pump, regardless of how much power the motor is actually generating.

Remember that if the fuel is returned to the swirl pot, it will gradually be heated to a point as it is effectively taking heat away from the fuel rail area as it circulates.
Returning to a main tank negates this possibility.

Hope that helps... /ubbthreads/images/graemlins/smile.gif

One last thing - don't forget UK gallons are BIGGER than US gallons..........I wonder if it's the same for HP??? - ONLY JOKING!!! (Keep the Flamethrowers at bay!!) /ubbthreads/images/graemlins/grin.gif

 

[Brett James-McCall]

[ QUOTE ]
One last thing - don't forget UK gallons are BIGGER than US gallons..........I wonder if it's the same for HP???

[/ QUOTE ]

Paul,
I believe so, I'm sure I read in a magazine that this is how Bugatti got round the 100HP Veyron issue. Apparently, it is less in Europe or something.

Brett

 

[Bill Musarra]

Follow up questions. Are all the "new" pumps all rotary vane? Is that the better type? I have seen many in the past that were very noisy on startup.

Bill

 

[Ron Earp]

There is a slight difference in hp. I think:

1 English hp = 746W
1 Metric hp (PS) = 735W

So, 1000 Metric hp (1000 PS) would be 735kW, but converted to English hp would be 985hp.

R

 

[Lynn Larsen]

Bill,

I can tell you that the noise of my Mallory hp pump is becoming quite tiresome. I will be looking for a quieter high pressure pump when I convert my fuel system to have a header tank, which will happen when I change the drive train. I only hope that the noise is not common to all inline, non-in-tank FI fuel pumps.

Regards,
Lynn

 

[Howard Jones]

Lynn, You clearly need louder mufflers!!!

 

[Mike Christian]

try the MSD pump...I just put one in my plane and it is pretty quiet. It is sold under different brands...

 

[dave harris]

Lynn, did you rubber mount both the pump side AND the screw/bolts heads on the opposite side of the panel? If you dont get the bolt heads too, it can really amplify the pump noise on the pannels. Or is it just the pump itself thats noisy?