Upgrading the fuel system on nearly any Mustang (from '86-present) is pretty straightforward. For early (return-style) applications, the installation of a 255-lph fuel pump will provide sufficient fuel flow for nearly 650-800 horsepower, assuming a system pressure of 40 psi, a supply voltage of at least 12 volts, and 0.5-brake-specific fuel consumption (BSFC).
Actually, testing has shown that most normally aspirated fuel-injected 5.0L and 4.6L applications exceed a 0.5 BSFC number and often dip down into the mid-0.4s. This means that the engine will require less fuel to produce a given amount of power. While your first thought might be that this entails a lean mixture, it is possible to increase the power output without affecting the air/fuel ratio, thus improving (decreasing) the BSFC number. Even a dedicated (normally aspirated) race motor could get by with a 255-lph, or certainly an Aeromotive Stealth in-tank pump (assuming proper wiring and fuse capacity).
Most normally aspirated engine can get by with 40 psi, but the same doesn't hold true for forced-induction applications unless overly large injectors are employed. Judging by the flow numbers in our pump test, combining a 255-lph in-tank pump with a Kenne Bell Boost-A-Pump should handle just about any 5.0L or 4.6L combination you are likely to throw at it, including high- horsepower, turbo, or blower engines.
Upgrading to a Stealth Pump from Aeromotive or TI pump from Walboro with the Boost-A-Pump will provide more fuel than you could even use. There are some minor exceptions to this rule, like the '11-up Four-Valve Coyote motor. Since the fuel system is self-regulated at just 55 psi (at the pump), a high-flow pump must be combined with large injectors if you plan to exceed 850 rwhp. The '03-'04 Cobra and Shelby GT500 both utilized dual pumps from the factory, so pump replacement requires a pair of pumps. Adding a Kenne Bell Boost-A-Pump to the stock pumps will take you beyond 800 hp with the right size injectors, making pump replacement unnecessary for all but dedicated race motors. Shelby currently employs the Boost-A-Pump on its Super Snake GT500 vehicles.
The Walbro GSS340 was the typical 255-plh pump employed on a variety of different Mustang and other applications. The Walbro TI F262 was a new in-tank pump designed for gas, while the TI F267 in-tank pump was the only one tested specifically designed for use with alcohol-based fuels. The Stealth from Aeromotive and Walbro TI pumps were high-flow in-tank pumps that easily out-performed the venerable 255, while the A1000 (offered in both inline and in-tank configurations) offered the most flow of any of the pumps tested. On some applications, the A1000 required the entire fuel system be upgraded with new plumbing, regulator, and wiring. Due to the extreme flow rates, the F262 and F267 TI pumps would require attention to the wiring and fuse components, as would other after-market/non-OEM pumps in dual (or triple) configurations.
18 Modern fuel pump assemblies...
18 Modern fuel pump assemblies have become very elaborate, making them all but impervious to simple pump upgrades. Short of a complete fuel system change, the answer is the Boost-A-Pump.
19 Prior to the introduction...
19 Prior to the introduction of the 5.0L Coyote, many of the modular motor applications relied on return-less fuel systems that incorporated a rail-mounted transducer to monitor the fuel pressure. These pressure transducers could be tricked into increasing the system pressure by applying boost to the vacuum fitting.
20 In addition to fuel pumps,...
20 In addition to fuel pumps, the Fuel Flow 3000 was also capable of flow-testing fuel rails. Shown here is a setup to test the pressure drop on the fuel rail used on a Kenne Bell supercharged 4.6L Two-Valve.
Common Injector Flow Rates vs. Power Output High-Impedance Injector Flow Ratings
|Injector||(0.5 BSFC)||(0.6 BSFC)|
|19 lb/hr||304 hp||253 hp|
|24 lb/hr||384 hp||320 hp|
|30 lb/hr||480 hp||400 hp|
|36 lb/hr||576 hp||480 hp|
|40 lb/hr||640 hp||533 hp|
|42 lb/hr||672 hp||560 hp|
|50 lb/hr||800 hp||667 hp|
|55 lb/hr||880 hp||733hp|
|65 lb/hr||1,040 hp||867 hp|
|75 lb/hr||1,200 hp||1,000 hp|
|85 lb/hr||1,360 hp||1,133 hp|