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In order to determine the proper size fuel pump you have to determine the brake specific fuel consumption (BSFC) of the engine. Brake specific fuel consumption in a nut shell is how much fuel (lbs per hour) the engine can consume per horsepower. The BSFC has a direct correlation with the efficiency level of the engine. For gasoline engines the BSFC is broken down between naturally aspirated and forced induction:
-Naturally aspirated: BSFC .45 to .50
-Forced Induction: BSFC .65 to .70
The higher the BSFC the more efficient the engine. In choosing the correct BSFC number lower compression engines should choose the lower number, higher compression engine choose the higher number. If using Methanol (alcohol) as fuel the BSFC is doubled.
You have to know two other bits of information to properly equate what size fuel pump you'll need; power level and weight of the fuel/gallon being used. For most gasoline equipped engines the fue/gallon is 7.25lbs/gallon.
Using the above information here is a simple equation to calculate the amount of flow you need from your fuel pump:
(Power x BSFC) x (1 + Safety Margin)=pounds/hour
(Pounds/hour)/7.25=gallons/hour
An example so you can follow:
500 horsepower gasoline engine
20% safety margin (always use at least 20%, this is a number representing the diffencies in the fuel system such as the fuel filter, lines and fitting (restrictions)
(500x0.70)x(1+.20)=420 lbs/hr
(420lbs/hr)/7.25=57.93 or 58 gallons/hour
To convert to something more useful lets put it in units of liters/hour since many aftermarket pumps are in these units.
gallons/hour=3.785liters/hour
so 58 gallons x 3.785=219.53 or 220 liters per hour.
Looking at what the aftermarket has to offer the Walboro intake 255lph fuel pump should provide enough fuel for 500-550whp level. A good indication that you need to run a larger fuel pump is that your fuel pressure drops while under boost. In order to monitor this you need to have a fuel pressure gauge. I prefer the gauges that mount on the fuel filters in the engine bay, but electronic ones with a sending unit to mount inside are nice
as well (much more expensive).
http://www.evans-tuning.com/techarticle_chooseafuelpump.html
-Naturally aspirated: BSFC .45 to .50
-Forced Induction: BSFC .65 to .70
The higher the BSFC the more efficient the engine. In choosing the correct BSFC number lower compression engines should choose the lower number, higher compression engine choose the higher number. If using Methanol (alcohol) as fuel the BSFC is doubled.
You have to know two other bits of information to properly equate what size fuel pump you'll need; power level and weight of the fuel/gallon being used. For most gasoline equipped engines the fue/gallon is 7.25lbs/gallon.
Using the above information here is a simple equation to calculate the amount of flow you need from your fuel pump:
(Power x BSFC) x (1 + Safety Margin)=pounds/hour
(Pounds/hour)/7.25=gallons/hour
An example so you can follow:
500 horsepower gasoline engine
20% safety margin (always use at least 20%, this is a number representing the diffencies in the fuel system such as the fuel filter, lines and fitting (restrictions)
(500x0.70)x(1+.20)=420 lbs/hr
(420lbs/hr)/7.25=57.93 or 58 gallons/hour
To convert to something more useful lets put it in units of liters/hour since many aftermarket pumps are in these units.
gallons/hour=3.785liters/hour
so 58 gallons x 3.785=219.53 or 220 liters per hour.
Looking at what the aftermarket has to offer the Walboro intake 255lph fuel pump should provide enough fuel for 500-550whp level. A good indication that you need to run a larger fuel pump is that your fuel pressure drops while under boost. In order to monitor this you need to have a fuel pressure gauge. I prefer the gauges that mount on the fuel filters in the engine bay, but electronic ones with a sending unit to mount inside are nice
as well (much more expensive).
http://www.evans-tuning.com/techarticle_chooseafuelpump.html
do you get a Litre converter????