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Mechanical Flow—We Asked the Experts About Mechanical Fuel Pumps

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Mike Dezotell of Dez Racing learned many years ago about the upper limits of an electric fuel pump in supercharged applications. Extensive knowledge in building and tuning ProCharger F-1R combinations told him to go right to a Weldon mechanical pump when his shop built Aaron Bates’ championship-winning Mustang.
By John Hedenburg

Photos Courtesy of the Manufacturers and NMRA

The electric fuel pump has been a staple in the street/strip racing community for decades thanks to its capabilities. Today, however, there are some competitors who are taking a different approach by ditching the time-honored tradition of an electric pump in favor of a mechanical one. The effective result with a swap to a mechanical pump is seen with an increase in power, an undeniable effect and one that piqued our curiosity. We did some digging by talking with a few manufacturers and several racers about the switch to mechanical pumps and the information was way beyond what we ever expected.

Pump vs. Pump

An electric fuel pump uses an electric motor that runs on battery power and, based on its design and flow capabilities, pushes fuel to the engine. It’s a very good and effective design, but can be limited by its power supply and the fuel flow capabilities. Basically, if you have an electric pump designed to flow four gallons/minute of fuel, which is its maximum flow despite the engine rpm or engine requirements.

A mechanical fuel pump, however, is a totally different animal. It consists of a mechanical pump (basically an internal impeller) that pumps fuel through the unit and to the engine. It does not take any electrical power to operate as it drives off the crankshaft via a hex adapter or cog belt attached to the crank pulley. Like a supercharger, as engine rpm increases so does the fuel pump impeller, thus delivering more fuel volume to the engine.

The Weldon Billet Racing Pump (P/N 34712) can handle fuel demands on engines well over 1,500 horsepower and has a fuel flow rate of six gallons-per-minute.

But Why Make the Switch?

As the cars get quicker and quicker, particularly the supercharged combinations in Edelbrock Renegade and Xtreme Street, the electric fuel pumps that have served so many racers well over the years are being taxed to their limits. The story is very clear once racers start to reference the data collecting from runs down the drag strip. As fuel flow becomes maxed out, the air/fuel readings become inconsistent when the engine is demanding more than the pump is capable of delivering. That is when it becomes time to switch over to a mechanically driven pump, like the ones offered by Aeromotive, MagnaFuel, and Weldon.

Jim Craig of Weldon Pumps in Oakwood Village, Ohio explained, “The electric fuel pump is a very good design but it has limits.” He went on to discuss some advantages to running the mechanical one over the electric and said “On a blower application, one advantage is weight and the other is flow. We sell mechanical racing pumps that bolt right up to the Chris Alston blower brackets that most ProCharger racers use.”

The Chris Alston Component Drive System (CDS) gear-drive features a built-in hex adapter, which is used to turn the fuel pump. He also explained that Weldon offers a cable-driven pump, which is turned by a cable that’s similar to a speedometer cable. That allows the fuel pump to be mounted in the trunk along with the tank. The Weldon mechanical pumps can be used in both alcohol and gasoline applications with flow between six and eight gallons-per-minute and are capable of supplying well over 2,000 hp worth of fuel. Craig concluded, “They are lighter by design and larger regulators and lines can be used, as well as front-mounted cells, which all aid fuel flow and performance.”

Kyle Flicker of Aeromotive agreed that the mechanical fuel pumps take less power to operate and offer varying pressure features. He inserted, “Our Billet Belt Drive mechanical pumps flow more fuel as the rpm of the engine increases. Where an electric pump has a set pressure and flow, the higher you rev the engine with a mechanical pump the more it will flow, which equates to more power. The pump, being mechanical, also eliminates the current draw that the load of an electric pump puts on the charging and electrical system. Our pumps can fuel an engine up to 3,600 hp on gas and 1800 hp on methanol, and are machined from billet aluminum.”

MagnaFuel also brings a mechanical pump to the party, its Outlaw 750, and according to Robbie Ward, it far outflows any of its electric versions and can be mounting in a number of configurations like the Aeromotive and Weldon offerings. Ward shared, “Our Outlaw 750 is rated at 150 psi and can supply over seven gallons-per-minute at only 4,000 engine rpm.” With that kind of flow results, Ward said it has been a very popular pump to step up to when customers outrun their electric fuel pump.

Magnafuel’s Outlaw 750 and 1000 pumps are rated at 7-8 psi at 4,000 engine rpm and can handle up to 150 psi of fuel pressure. Like many other mechanical pumps, this one is made from billet aluminum, ensuring high quality and dependability.

Edelbrock Renegade racer Adam Arndt said they made the switch to a mechanical fuel pump two years ago, right after the NMRA season concluded and in time for the World Cup Finals at Maryland International Raceway. The savvy Renegade racer is one of many enthusiasts that rely on a Chris Alston CDS gear-drive setup to turn a ProCharger supercharger. The unit has a built-in hex drive on the front of it, easing the installation of a mechanical pump on his combination. Arndt says it took mere minutes to bolt on his Weldon pump.

The Pumpkin Spice Mustang, on loan to Brian Mitchell for the first half of the NMRA season, is rolling proof of the effectiveness in switching to the mechanical setup. Arndt admitted “We are seeing improved fuel injector flow rates and performance on our graphs. With the electric pumps our injectors were pretty much at 100-percent duty cycle, which means that they were virtually open the entire time (not pulsing at all) trying to keep up with the fuel demand of the engine. But now, with the mechanical pump, the injectors don’t need to work as hard and are having a much easier time keeping up with the power levels without being maxed out. Also our air/fuel ratios are much better and consistent, which is a huge part of making optimal power.”

Cost vs. Gain

Cost is always a concern and the switch to a mechanical fuel pump setup is surprisingly more reasonable than one would imagine. “A good mechanical pump can generate upwards of 3,000-plus hp,” explained Arndt when talking about the capabilities of most pumps. He continued, “when you factor what a good mechanical setup will run, with lines, fittings, adapters and things, you are looking at approximately $1000, give or take and depending on the pump and setup you choose to run.” According to Arndt, a fuel system with an electric pump, relays, wiring, and charging system, the system costs go higher than a billet mechanical pump.

Aeromotive’s mechanical fuel pump (P/N 11105) features a billet aluminum body and can deliver fuel demands up to 3,600 hp in gasoline applications and 1,800 hp when delivering methanol.

Mike Dezotell of Dez Racing, the shop that built, maintains, and tunes the 2016 Edelbrock Renegade championship winning car of Aaron Bates, explained that another unforeseen advantage is load on the charging system. Today, the wide-ranging capabilities of engine management systems is no secret, so reducing draw on the battery will only help the big picture for all the other systems relying on the juice. Arndt even told us how they have removed the alternator immediately following the addition of a mechanical fuel pump. “The battery never drops below 12 volts, but we do charge it after every run,” he confessed.

“We are running our cell in the front and the advantages are huge,” disclosed Arndt. Relocating the fuel cell to the front reduces weight and increases efficiency of the fuel system. The fuel no longer has to travel through 15 feet of line from the rear of the car to the engine up front. That means less fuel line and fittings for less weight, as well as making the setup more compact and simpler.

Conclusion

Increased power thanks to better fuel volume—particularly with supercharged cars in the Renegade ranks—reasonable pricing, ease of maintenance, and consistency all prove that if your application is making big power, then turning to a mechanical pump should be in your future.

Aeromotive Inc.
913/647-7300
www.AeromotiveInc.com

Dez Racing
508/336-6588
www.DezRacing.net

MagnaFuel Products Inc.
719/532-1897
www.MagnaFuel.com

Weldon Pump
440/232-2282
www.WeldonRacing.com


Mike Galimi
Mike Galimi
Mike Galimi is the Director of Content & Marketing at ProMedia Publishing and Events with nearly 20 years of experience in motorsport writing and photography.
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