THERE ARE TWO TYPE OF TURBOCHARGING SYSTEM :-
A) CONSTANT PRESSURE TURBOCHARGING :- IN THIS SYSTEM, THE EXHAUST BRANCH OR PIPE FROM EACH INDIVIDUAL CYLINDER IS LED INTO A COMMON MANIFOLD. AS THE EXHAUST GAS BLOWS INTO THE MANIFOLD, EDDIES ARE SET UP WHICH HELP DAMP OUT ANY PRESSURE WAVE CAUSED BY THE INFLUX OF THE EXHAUST GAS. THE VOLUME OF THE MANIFOLD MUST ALSO BE LARGE ENOUGH TO ACCOMMODATE THE GAS FLOW FROM INDIVIDUAL CYLINDERS WITHOUT CAUSING ANY LOCALIZED PRESSURE RISE IN THE MANIFOLD AS EXHAUST GAS LEAVES THE CYLINDER.THE COMBINED EFFECT OF HAVING SUFFICIENT VOLUME IN THE MANIFOLD TOGETHER WITH THE EDDIES IN THE EXHAUST GAS FROM INDIVIDUAL CYLINDERS CAUSES THE PRESSURE IN THE MANIFOLD TO REMAIN VERY NEARLY CONSTANT. THE EXHAUST GAS IS LED FROM THE MANIFOLD INTO THE EXHAUST GAS TURBOCHARGER AT A CONSTANT PRESSURE.
B) PULSE TYPE TURBOCHARGING :- IN PULSE SYSTEM, MAXIMUM USE IS MADE OF THE ENERGY IN THE EXHAUST GAS DURING THE BLOWDOWN PERIOD, BY DESIGNING THE EXHAUST VALVES SO THAT THEY HAVE THE LARGEST POSSIBLE PORT AREA. THE EXHAUST CAMS ARE DESIGNED TO GIVE THE MOST RAPID POSSIBLE OPENING OF THE EXHAUST VALVE. WHEN THE EXHAUST VALVE OPENS, THE BLOWDOWN OF THE EXHAUST INTO THE EXHAUST PIPE CAUSES A PRESSURE WAVE OR IMPULSE TO PASS DOWN THE EXHAUST PIPE TO THE NOZZLE PLATE IN THE EXHAUST TURBINE. THE STATIC PRESSURE OF THE EXHAUST GAS DURING THE IMPULSE PERIOD IS GREATER THAN THE AIR CHARGING PRESSURE, THEREFORE NO CYLINDER SHOULD BE EXHAUSTING AT THE TIME THE IMPULSE PASSES IN THE EXHAUST PIPE, OTHERWISE EXHAUST GAS MAY BLOW BACK INTO THE CYLINDER. ENGINE TURBOCHARGED ON THE IMPULSE SYSTEM MUST HAVE THE EXHAUST PIPES CAREFULLY GROUPED ACCORDING TO THE ENGINE EXHAUST VALVE TIMING. EACH GROUP OF EXHAUST PIPES HAS A SEPARATE ENTRY INTO THE EXHAUST TURBINE, AND EACH ENTRY LEADS TO IT’S OWN NOZZLE GROUP.
