The amount of horsepower your engine can make is entirely controlled by the amount of fuel that can be burned. If we know how much fuel an injector will pass then it is easy to see how much power that injector can provide. The chart above shows the maximum horsepower that could be produced in our engines given a specific injector and fuel pressure. These figures represent engine horsepower (gross) not wheel horsepower (net), advertised horsepower figures are net figures. We show various fuel pressure settings because some people use other than stock fuel pressure. The figures in bold represent the 55 pounds our stock pressure regulators are set at. Boost will increase fuel pressure on these regulators about one pound of pressure for every pound of boost. This keeps the fuel pressure differential constant (the difference between fuel and atmospheric pressures). The formula used for the chart below:

Where, FR = flow rate in pounds of fuel per hour, 4 is # of injectors or cylinders, .85 is the injector duty cycle, and BSFC (Brake Specific Fuel Consumption) = .55.

Chrysler Corp. rates each of the injectors listed for flow at 55 psi. To find the flow rate for other pressures, take the square root of the new pressure divided by 55, and multiply by the flow rate at 55 psi. Example for the 804 injector at 65 pounds, take the square root of 65/55 times 36, or 1.0871 * 36 = 39.1356 pounds per hour. Then to get the power figure, 39.1356*4*.85/.55 = 133.061/.55 = 241.9292. It should be noted that in all likelyhood most engines will never attain these maximum power settings. These figures give the maximum power that can be achieved, but because of varying states of engine buildup, engine tune, and atmospheric conditions (temp, humidity), actual results will probably be at least 10-25% lower.