Abstract: A method of controlling the air supply to a scavenged internal combustion engine having a blower for suppling air thereto and bypass means for allowing a bypass air flow from the outlet side of the blower to the inlet side thereof, the method including regulating the bypass air flow through the bypass means to provide a variable rate of air flow therethrough and regulating the flow of ambient air to the blower to thereby control the pressure of the intake air supply to the blower and controlling a supply of recirculated exhaust gas introduced upstream of the blower by controlling the flow rate of ambient air to the blower such that a requisite pressure is generated upstream of the blower to thereby control the exhaust gas flow rate.