Thread: Need Help w/fuel pump selection

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Originally Posted by 63409ss

I'm installing a 383 440HP in a 79 Corvette with a turbo 350 for a friend is there an easy way to figure out which mechanical fuel pump I should use Summit offers 2 different Holley's but I don't know which to choose.Engine has no name dual plane aluminum intake,Holley carb,aluminum heads,roller rockers,high performance HEI distributor It was advertised at 440HP and dynoed at 413HP in hot air temps.Hope this helps!!!

Here, I'll give you an answer you can use for the rest of your life to size pumps for a given hp.
Most any internal combustion engine will use 0.5 (1/2) pound of fuel for each horsepower hour. For instance, 440 times 0.5 equals 220 pounds per hour of fuel burned. Now, since gasoline weighs about 6 lbs per gallon, we can divide 220 by 6 and find that the motor will use about 36.66 gallons per hour running at 440 horsepower.

Now, rule of thumb says to double that because the pump will have to pull fuel through small diameter tubing and against the direction of the car (under acceleration, the fuel tries to go back toward the tank, making the pumps job harder). So, if we double 36.66, we find that we will need a pump that will deliver 73.32 gallons per hour running at 440 horsepower. Now, of course, the motor will only be making that kind of horsepower for an instant at a time in a street or street/strip application, so some concession can be made if you have a pump that delivers close to that.

The more important thing to consider when choosing a fuel system is the limit of the needle and seat in the carburetor. A Holley, generally speaking, will be ok with fuel pressure up to about 6 1/2 lbs at the carburetor fuel inlet. The needle will not be able to seal up against the seat with pressure over that and will flood the intake manifold with raw fuel. This will provide you with an unbelievable tuning nightmare. Mount a 0-15 fuel pressure gauge temporarily on the cowl of the car with duct tape or tie wraps and plumb it to the fuel inlet of the carb so that you can observe fuel pressure as you drive. If need be, install a regulator and lower pressure to around 6 pounds. When you have the pressure dialed in, you can remove the gauge and be assured that your fuel system is working as designed.