The true virtue of sequential fuel injection is its ability to respond quickly to sudden changes in the way an engine operates. It only has to wait until the next intake valve opens instead of the next complete revolution of the engine.
Choosing proper-size injectors is always a big concern. If you have a ballpark idea of the amount of horsepower your 'Stang's engine makes, this calculation will ensure you're using injectors that are big enough to support it:
| LB/HR = Injector Size x Number of Injectors |
Horsepower at 100 percent Duty Cycle =
LB/HR |
Brake-specific fuel consumption (0.5 naturally aspirated/0.6 turbo/0.65
supercharger/0.7 nitrous) |
Injectors typically run at 80-percent duty cycle (0.8) and 43.5 psi of fuel pressure. Power at 100-percent duty cycle multiplied by 0.8 is the calculation that must be performed to determine horsepower levels for injectors when they're operating normally.
The amount of fuel supplied to the engine is determined by the size of the fuel injectors and their pulse width-the amount of time the injectors remain open, which is controlled by the PCM.
Notice the major nozzle difference between this 42-lb/hr injector (left) and a stock 19-lb/hr squirter. ACCEL has a cool fuel-injector calculator (PN 74142G) that lets you quickly determine what size you need. There are also several online calculators.
BBK's Universal 5.0 fuel rail kit is primarily for stock 'Stang fuel systems, but we think it's a great idea when you step up to 11/42-inch hose or AN -10 braided line (Tech Inspection, Nov. '06, p. 184). These aluminum pieces are designed to take the pain and suffering out of trying to fit larger fuel rails without contacting the distributor. Specially machined fittings included with BBK's kit allow fuel feed and return lines to be connected to stock-style, spring-lock fittings if they're still being used.
These Siemens VDO Deka IV series long injectors feature pencil-style nozzles that are angled to distribute a steady stream of fuel at the intake valves. We recommend 60-lb/hr units such as these for boosted or nitrous-injected applications that will make as much as 650 rwhp.
Fuel Tanks And Cells
A stock fuel tank needs no explanation. It's technically a container made of steel that stores the gasoline to feed a 'Stang's hungry engine. A stock fuel tank can be modified with a sump to suit higher-performance street and full-on racing applications.
A fuel cell is a replacement many 'Stangbangers choose to install when fuel system upgrades are in progress. They're used as safety equipment for off-road or racing applications, mainly because they're designed to be leak-proof in the event of a rollover accident. If they do leak, it will be slow thanks to bladders and foam inserts inside the cell. Cells are made of plastic or aluminum, reducing the possibility of sparks flying everywhere and causing a fire if it's punctured or dragged on the ground.
Additional fuel demands must be met when nitrous oxide is the power adder of choice. Failure to add compensatory supplemental fuel to a nitrous mixture usually brings on a lean condition that ultimately leads to cylinders full of molten aluminum. Auxiliary enrichment tanks are helpful in this situation. A 1-gallon tank can be easily mounted in a Mustang's engine bay with lines plumbed into the fuel side of a nitrous unit for better nitrous efficiency and performance.
As a rule of thumb for general safety, any fuel tank or cell should always be properly vented.
A sump tray ensures that there's always a solid flow of fuel available for the pump, especially during hard launches or other aggressive driving conditions. Fab-Tech Custom Fabrication and Welding of Chatsworth, California, makes this weld-in sump tray (for the do-it-yourselfers) and complete, sumped '99-'04 fuel tanks for converting returnless fuel systems to return-style. Fab-Tech's New Edge tanks retain the OEM fuel-pump basket and sending unit, and all the evaporative emissions-control connections and tubes.
This AlumaStealth fuel tank ('79-'93 Mustangs) by Rick's Hot Rods was detailed in our Jan. '07 Tech Inspection (p. 180). The 14-gallon tank is a direct-fit replacement for stock fuel tanks. It features Aeromotive's A1000 high-volume electric pump mounted inside and will support serious street horsepower while maintaining a stealthy appearance. Using a continuous-duty relay is imperative when wiring a standalone fuel pump similar to this setup. The relay should be located close to the battery and the pump.