PURPOSE: To improve an extent of torque ever so high, by feeding a compressor with fuel in times of sudden acceleration and quick starting, while connecting the compressor to a turbocharger upon opening a valve, and making the compressor so as to use it as an auxiliary engine.

CONSTITUTION: A valve 19 is opened and a valve is closed, then a control valve 31 being installed in a fuel feed pipe 27 is closed. With output of an engine 1, air inside a cylinder 9 of a compresser 8 is compressed. This compressed air is stored in an air tank through an exhaust pipe 17, a branch box 18 and a charge valve 20. When compensating low torque in the engine 1, the valve 19 is closed, the valve 22 is opened and the control valve 31 is opened. The exhaust pipe 17 of the compressor 8 is connected to the turbine of a turbocharger and simultaneously with this connection, fuel fed by a fuel injection nozzle 26 explodes in combustion inside the cylinder 9 whereby the compressor serves as an engine, thus exhaust gas is fed to the turbine.