AFM used Delphi's 75-lb/hr,...
AFM used Delphi's 75-lb/hr, low-impedance race injectors to feed the blown Pony's 4.6 and ensure that air/fuel levels didn't reach the dreaded "point of crispy" (Rick's name for a max-severe lean condition that potentially can kill a motor) during the attempts to hit the target of 600 hp to the wheels.
Aeromotive of Lenexa, Kansas, is one company that fully understands how important it is for engines with power adders to have fuel systems that can support major horsepower. The company's original Dynamic Fuel Systems for '87-'95 Mustangs and Digital FMU for '96-'04 Mustangs are great solutions for most cars. Basically, a mechanical FMU (fixed boost-to-fuel ratio) and Aeromotive's DFMU (variable, custom ratios) act as a regulators and fuel-pump controllers that increase fuel pressure when they sense boost, by managing the output of an additional fuel pump that was incorporated in the system. Until now, the DFMU has been an easy solution for owners of returnless-fuel systems who wished to maintain driveability under low-boost conditions and support 500 hp at wide-open-throttle in their street 'Stangs. The DFMU takes to a new level the process of using increased fuel pressure to compensate for a lack of injector size. When it senses boost, the unit controls an auxiliary, variable-voltage, inline pump and allows the creation of a custom fuel-pressure curve that eliminates the fat midrange/lean top-end problems of old.
Knowing that Mustang enthusiasts are always pushing the envelope for more power, Aeromotive engineers returned to the lab and developed a new, improved returnless-fuel supplement that's really impressive. Targeted for those applications where larger (55-160-lb/hr), typically low-impedance injectors are used, this system bridges the canyon between 600 and 1,000-plus horsepower for returnless fuel systems-on the street. Until now, adding twin SVT Focus fuel pumps and '03-'04 Cobra fuel tanks to returnless Mustangs has been an effective-if labor-intensive-solution for higher-horsepower GTs.
The SVT Focus fuel pump is...
The SVT Focus fuel pump is being heralded across the Internet as the hot-ticket in-tank replacement for the stock unit in '99-'04 'Stangs. AFM installed this 217-lph fuel feeder (it's a direct replacement) in the GT's tank prior to reinstalling the tank. But Aeromotive designed On-Demand to fulfill fuel needs and fully support the stock fuel pump in Mustangs' returnless systems.
Now Aeromotive has an On-Demand Fuel System, which actually complements the stock fuel system-including the pump-by enabling the car to be driven in non-to-low-boost conditions on the stock fuel system alone. The system is comprised of Aeromotive's Eliminator fuel pump (activated by a manifold boost sensor or other method), a one-way check valve, and a regulator that delivers a constant fuel-pressure value under load, maintaining a 1:1 ratio with boost if necessary. As higher engine load and fuel demand are created by boost or nitrous, the Eliminator pump and boost-reference regulator contribute fuel volume and sustain system pressure. Of course, fuel injectors that can support the intended max horsepower level are required for the On-Demand system. If injector size is not sufficient enough to meet fuel-flow requirements, Aeromotive's DFMU must also be used.
"Any engine equipped with enough injector to support the target horsepower needs fuel volume sufficient to maintain the desired base pressure and a 1:1 rise with boost," according to Bret Clow, Aeromotive's director of Technical Service. "Our On-Demand Fuel System basically augments fuel flow by supplying vastly increased volume at a constant delta pressure. Delta pressure is the differential or difference between the fuel pressure in the fuel rail and the air pressure in the intake. Base or static pressure is considered the desired delta, and with a 1:1 boost reference, the fuel-rail pressure will always stay the correct number of psi above the manifold pressure, ensuring a constant fuel-flow rate through the injector any time it's open."
Anderson Ford Motorsport recently installed a prototype of the On-Demand Fuel System on a ProCharger-blown, '00 GT and gave it a workout on its dyno. Sure, the plan was to see how much horsepower and torque the system would support, but AFM also wanted to keep a close eye on air/fuel ratios (with and without the On-Demand kit in action) and to hopefully determine the overall effectiveness of Aeromotive's new setup, with respect to driveability.