52 as is commonly practiced in the art the supercharger assembly 100 may comprise an intake duct 126 a turboexpander assembly 120 a high pressure air supply line 138 control valve 132 pressure regulator 130 interconnecting lines 136 and 137 and air feed line 148 in addition the supercharger assembly 100 may also include a compressor 164 compressor inlet line 176 aftercooler 178 check valve 180 air tank 160 and interconnecting lines 172 176 184 and 186 the intake duct 126 has an upstream end 108 fluidly connected to a source of intake air and a downstream end 110 fluidly connected to the intake passage 22 suitable sources of intake air include 1 atmospheric air which may be provided at near ambient pressure and 2 output air from a supercharger such as engine driven supercharger exhaust gas turbocharger or an electric turbocharger which may be preferably provided at a pressure higher than ambient atmospheric pressure the upstream end 108 may be equipped with a pressure sensor 156 and a temperature sensor 158 the downstream end 110 may be equipped with a pressure sensor 154 and a temperature sensor 151 the intake duct 126 may also include a valve 168 to regulate air flow therethrough the valve 168 may be installed upstream of the location where the air feed.