An engine assembly comprises: an internal combustion engine having: a combustion chamber; an air inlet for supplying air to the combustion chamber; a fuel injector for supplying fuel to the combustion chamber; an exhaust outlet for releasing exhaust gas from the combustion chamber and a rotatable drive shaft, wherein combustion of fuel in air within the combustion chamber results in rotation of the drive shaft. The engine assembly further comprises: a turbocharger system comprising: a turbine configured to recover energy from exhaust gas provided via the exhaust gas outlet; and a turbocharger compressor configured to receive energy from the turbine and thereby to compress air for use in combustion of fuel in the combustion chamber. The engine assembly further comprises: a supercharger system comprising a supercharger compressor configured to receive kinetic energy from the drive shaft and to compress air for use in combustion in the combustion chamber. The engine assembly further comprises: a flywheel configured for kinetic energy storage; a first linkage between the drive shaft and the flywheel, wherein the linkage comprises a variable belt drive; and a second linkage between the first linkage and the supercharger compressor.