Engine turbocompressor controllable bypass system and method

A system for a turbocharged internal combustion engine includes an engine (10) having a charge inlet (14) connected to the compressor outlet (26) and an exhaust outlet (16) connected to the turbine inlet (28) for driving the turbocharger (18) with hot exhaust gas and supplying compressed air to the engine (10) for combustion. A bypass duct (44) connects the compressor outlet (26) to the turbine inlet (28) for diverting a portion of the compressed air around the engine (10) to the turbine inlet (28). A control member (50) selectively controls the diversion of air. An operating method for the system involves controlling surge in an engine turbocharger compressor by diverting a portion of compressed air to the turbine inlet (28) to limit compressor air pressure and insure sufficient air flow to avoid compressor surge. Preferably, the diverted air enters a distal part (46) of an engine exhaust header (16) for mixing with the exhaust gases prior to passing into the turbine inlet (28). Other benefits are disclosed.