Need to know :

1. injector rated pressure

2. operating fuel pressure (stock)

3. Firing method (how many times a cycle)

4. Pressure control

 

1. injector rated pressure - The stock LT1 injectors are flow rated at 3bar = 43.5psi. The injector flow constant in the 94-97 PCM is about 24.9 #/HR.

2. operating fuel pressure (stock) - The stock FPR is set to keep a differential pressure, measured between the fuel rail and the intake manifold of 43.5psi. Factory tolerance is 41-47psi. Remember, you will only see that pressure when there is no vacuum applied via the vacuum compensation line.

3. Firing method (how many times a cycle) - The batch-fire 93's fire each injector once each crank revolution (four injectors at a time), hence twice in a 4-stroke cycle. Since they are batch fire, they are not timed to the individual cylinder firing. The 94-97 is a full sequential, and the injector fires in sequence, based on the data coded into the Optispark low resolution pulse pattern. Each injector fires once per two crank revolutions = once per 4-stroke cycle.

4. Pressure control - The FPR acts to maintain the rail pressure. Its located in the return line, so it works by closing down the return flow until the pressure in the rails reaches the design value. There is a vacuum compensation line on the FPR that pulls the rail pressure down in direct proportion to the intake manifold vacuum, insuring the the differential pressure across the injector is held at a constant 43.5psi.

 

thanks Fred!