There was a day when it was difficult to find cheap replacement injectors to handle 500-600rwhp. There were few options for high-impedance style injectors other than the 42-pound Ford Motorsport or 50-pound MSD units. The aftermarket fuel injector industry has progressed rapidly in recent years, and as a result, there are many makes and sizes available to most performance enthusiasts. Larger injectors are needed to handle higher power levels in modified cars. As a general rule of thumb, the following equations are helpful in selecting the correct size injector to support the required power level.

To calculate the size of a particular application:

– Injector Flow Rate (lb / hr) = Engine HP (1) x BSFC (2) – Number of Injectors x Injector Duty Cycle (3)

Gold

– Injector flow rate (cc / min) = Engine HP (1) x BSFC (2) x 10.5 – Number of injectors x injector duty cycle (3)

An old trick some of the “Tuners” used to do was to tweak the 30lb / 36lb Ford Motorsport units to increase flow. There are still street racers using these modified injectors today with excellent results for their intended purpose. Generally, 30-pound injectors convert to 47-pound injectors and 36-pound injectors can become 66-pound / 72-pound / 77-pound injectors.

Additionally, there are some original equipment manufacturer bosch style units used by Ford that can also be modified to flow 47 pounds. This method of modifying certain Ford / Bosch style injectors will dramatically increase fuel delivery without significantly compromising the injector spray pattern or vehicle emissions. From a very high level, here are the steps to modify the fuel injectors;

  1. Remove the pivot cap, o-ring, and insulator.
  2. Remove the diffuser plate by filing around the weld.
  3. Install new pivot caps, o-rings, and insulator.
  4. Have a professional service shop flow test the units and ultrasonically clean them.

The problem is that the actual procedure is not well understood and it is very easy to destroy a fuel injector if done incorrectly. Care must be taken when removing the diffuser plate, and the injectors should be flow tested and ultrasonically cleaned (good practice for used injectors) to verify flow rate. Once the injector size is known, the computer / maf can be calibrated to match the new flow rate to ensure proper air-to-fuel ratio (this is something that should be done independently of the aftermarket fuel injector). accessories used).

When this procedure is done correctly, these modified fuel injectors work very well and will easily help street or street cars that easily make 400-600 horsepower. There are many that are still used today. It’s still an inexpensive way to get larger units for car owners on a budget.

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