Mallory offers a variety of fuel pumps and pressure regulators to meet the needs of most street, performance, marine, and racing applications. Whether your vehicle is carbureted or fuel injected, you will find a Mallory fuel pump and regulator to feed fuel to your engine.

• Do I need a mechanical or electric fuel pump?
• How much pressure and volume of fuel does my engine need?
• Do I need multiple fuel systems on my vehicle (example, one for the engine and one for a nitrous system)?
• Is my engine running on gasoline or alcohol?
• What type of regulator do I need?

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How To Calculate Engine Fuel Volume Requirements

    A fuel system is just that - a system! All the pieces must work together. The current trend is to run a pump that is much bigger than should be required to compensate for deficiencies within the system. Simply buying and installing the biggest pump you can find will not be enough if the rest of the system is poorly thought out. The same can be true buying a pump based upon price or what you think is enough fuel pump. Either deficiency can also easily drain the wallet if you run out of fuel and start damaging engine parts ... not to mention losing races!

   The following information will focus on electric fuel pumps. Mechanical fuel pumps are not worth the effort unless you are mandated by the rules of your class (as in many circle track applications). You can use the same basic knowledge with your mechanical fuel pump in regards to requirements and fuel regulator choices.

   Fuel pumps are generally rated in gallons per hour (GPH) or liters per hour (LPH). Mallory offers pumps rated at 70, 110, 140, 160, and 250 GPH, and also 190 and 225 LPH. 

   A typical engine uses 0.5 pounds of fuel (gasoline) per hour to make each horsepower. Gasoline weighs in at approximately 6 pounds per gallon. To calculate fuel consumption let me show you by example. Lets say we have a 400 HP engine (or nitrous system) and we will use the following formula:

    If you installed a pump rated at 33 GPH on a 400 HP Nitrous system the engine would experience severe fuel starvation and your wallet would cringe in "empty" pain!  WHY?

    There are several reasons ... However, the main reason is the way that pumps are rated. Fuel pumps are rated at "zero" pressure (also known as "free flow"). Rating a pump at zero pressure is useless because the pump will never be at zero pressure when it is operating in the vehicle. As fuel pressure increases, the fuel pump slows down and fuel output is reduced. If you use a standard "dead-head" type regulator, the pump may be forced to produce as much as 25 PSI. At this 25 PSI the actual output GPH of the pump is much less than at "free flow".

    All of this makes choosing a pump size difficult. You may use the following as a fuel pump "rule of thumb". Additionally, it is a good idea to give your system a bit of safety cushion. I always run a pump slightly larger than what I need just for insurance. This also addresses one of the questions above as knowing what style fuel pressure regulator you are using.

        For Dead-Head type regulators:
            Multiply maximum horsepower by .23 to calculate minimum pump size in "free flow" GPH.
            Example: 400 HP x .23 = 91 GPH "free flow"
 
        For Return-Style regulators:
            Multiply maximum horsepower by .17 to calculate minimum pump size in "free flow" GPH.
            Example: 400 HP x .17 = 68 GPH "free flow"

     With either of the two scenarios above you would want a minimum of 110 GPH. But, for the return style regulator system you would use the Mallory 140 GPH pump (part #4150) because the smaller pumps are not compatible with return style regulators. To assist you with pressure regulator selection we have an article to help you here.

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