This is for turbo
cars, to eliminate the delay in boost
when you let the gas up and the turbo compressor wheel slows down. Also known as a Bang-Bang System
, because of the loud explosions that it produces from the exhuast.
When the driver releases the gas the engine ignition timing is altered so that a portion of the air/fuel mixture escapes into the exhuast before the spark fires. Coming in contact with the extremely hot exhaust manifold ignites the fuel, and the expanding gases go through the turbo keeping it at optimum RPMs so that when the driver presses the gas again there is a consistent level of power.
Only used for race cars, and especially rally