Abstract: A turbo charger for an internal combustion engine includes a turbo charger housing defining a spool axis and including an exhaust chamber having an exhaust inlet and an exhaust outlet. The turbo charger housing also defines an air compressor chamber having an air inlet and an air outlet. A spool is mounted within the turbo charger housing for rotation about the spool axis. The spool includes a spool shaft with an exhaust turbine wheel mounted at one end and an air compressor wheel coaxially mounted for common rotation at the opposite end of the spool shaft. A compressed gas injector is mounted to the exhaust chamber of the turbo charger housing for providing a compressed gas flow to the exhaust turbine wheel from a source external to the turbo charger housing in order to supplement power from the exhaust to rotate the spool.