A supercharged internal combustion engine has a supercharger operable to selectively supply a mass of air from below through above atmospheric air pressure according to the operating requirements of the engine. The supercharger has a shuttle combined with a throttle valve that controls the mass of air directed to an air mass bypass opening and supplied to the internal combustion engine. The shuttle has rollers that ride on rails that allow the shuttle to move to open and close the air mass bypass opening in communication with a casing that directs a mass of atmospheric air and a bypass mass of air interfused with the mass of atmospheric air to an air mass inlet of the supercharger.