A power assembly includes an internal combustion engine including an air intake line and an exhaust gas line having at least one heat exchanger. The power assembly further includes a Brayton cycle system capable of providing additional power to the main internal combustion engine and that includes a gas compressor, a fuel burning heater and a turbine linked to the compressor so that air is drawn into the compressor where it is pressurized, the pressurized air is further heated by flowing through at least one heat exchanger where it exchanges heat with exhaust gases from the main internal combustion engine, the heated and pressurized air is further heated by the fuel burning heater and is thereafter expanded through the turbine where a first fraction of the work extracted by the turbine is used to drive the compressor and a second fraction of the work extracted by the turbine is used to bring additional energy.