A supercharged engine includes a crankshaft operable to receive and output power produced by combustion within the engine. The crankshaft is rotatably supported in a case, and a supercharger is driven from the crankshaft by an endless drive member. The supercharger is adapted to compress intake air supplied to the engine when driven from the crankshaft. A mount has a track slidably supporting the supercharger relative to the case so that tension in the endless drive member is adjustable and set in relation to a position of the supercharger relative to the case. The mount is self-adjusting to maintain an operating tension in the endless drive member.