To provide an engine unit capable of recovering heat in a simple and efficient method.

The engine unit is configured to incorporate a turbo therein from an internal combustion engine, and a heat recovery system comprising first recuperative turbines (2, 2') suitable for supplying a mechanical force to the engine, and arranged on an exhaust line (1) of exhaust gas from the engine, and a closed circuit (6) comprising a working fluid, a heat exchanger (8) arranged at downstream of the exhaust line of the first turbine suitable for transferring heat from exhaust gas to the working fluid, and second turbines (9, 9') suitable for being moved by the working fluid, wherein the second turbine is characterized to be suitable for supplying a mechanical force to the engine.