Page 2 of Fuel Pumps by Holley Performance Products, Inc.

fuel pumps technicalinform at i o n fuel pumps regulator technical information holley offers a wide selection of both mechanical and electric fuel pumps for a variety of street performance and race applications selecting the proper fuel pump for your vehicle however begins with understanding your engine s fuel requirements fuel requirements typically at wide open throttle full power an engine requires 0.5 lbs of fuel per horsepower every hour a gallon of gasoline weighs approximately 6 lbs therefore an engine rated at 350 horsepower will require about 175 pounds 29 gallons of fuel every hour 350hp x .5 lbs 175 lbs of fuel 175 lbs/6 lbs 29 gallons per hour fuel pressure and volume the relationship of pressure to volume is inversely proportional that is as pressure increases the volume will decrease everything else being equal a certain amount of fuel pressure is always required to maintain engine performance by assuring that fuel is available on demand also other factors and conditions must be taken into account such as acceleration g-forces and friction within the fuel system itself at the same time,however an adequate fuel volume is needed to ensure that the proper amount of fuel can always flow to the engine especially during peak demand situations a basic understanding of this critical pressure/volume relationship is needed when designing the proper fuel supply system for your vehicle fuel line system the fuel line system should be routed to avoid running near hot spots such as various exhaust system components and designed to promote maximum fuel flow most factory stock fuel systems utilize 5/16 fuel lines this size works well on street applications with stock engines when the horsepower requirements go up however the inadequacy of this line size soon becomes apparent a #6 3/8 line size is sufficient for all street performance applications and some racing applications #8 1/2 fuel lines are used on everything else including alcohol applications avoid using rubber fuel lines or use them sparingly for two reasons first rubber is more resistant to the flow of fuel than any hard line an actual pressure loss can be measured over distance second for safety s sake it s not a good idea to use rubber fuel line especially when using a high pressure performance fuel pump 5/16 1/2 fuel line sizes fuel pumps 3/8 fuel line fittings like the fuel line fuel line fittings are also a very important element in the total fuel line system and should not be overlooked obviously the fittings should be the same size as the fuel line also if at all possible you want to minimize the use of 90° fittings avoid sharp turns or bends in the fuel line routing these cause undue restrictions to the flow of fuel 190 www.holley.com

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