The development program ran into many problems with this engine, including the original electronic control system, compressor/turbine mismatches, combustion instability and control issues at altitude leading to compressor stalling The produced -8, -8A and -8B engines were all derated from the original design specification on both thrust and specific fuel consumption.

By the time the engine reached production, the rear nozzle had an iris-type "petal" design.

The same long control rods now pushed or pulled a ring that ran on rollers, which in turn opened or closed the iris.

The original design, using an electronic control system, would have allowed continuous adjustment of afterburner thrust from minimum to maximum.

This was abandoned when the electronic control could not be made acceptably reliable; the final afterburner was an "ON/OFF" unit.