Abstract: A turbocharger for an internal combustion engine having, essentially, a one-piece housing with an intake port on top and an outlet port on the bottom. Both ports are surrounded by standard carburetor flanges so that the carburetor may be removed from the engine and mounted directly on the turbocharger and then the entire assembly mounted on the engine as a unit, with the turbocharger intermediate the carburetor and the engine. A generally horizontal passageway extends from the inlet opening to the axial inlet of a turbine compressor, and the compressed air/fuel mixture is projected radially downward through the discharge port. A bypass port opens through the bottom of the horizontal passageway directly to the discharge port, and a shut-off valve there is held open at low engine loads as the compressor turbine gains velocity, being driven by the exhaust gases.