The invention is intended to optimize the recovery of the residual energy contained in the exhaust gases of an internal combustion piston engine by means of a turbocharger group, in which each cylinder (1) from which the combustion gases escape through the exhaust pipe (5) is equipped with a turbine (7), and the volume (5) between the exhaust valve (3) and the inlet of the turbine (7), detrimental to the efficiency thereof, is minimized by the attachment of the turbine directly on the cylinder head of the engine without the intermediary of a collector and, the counter-pressure acting on the piston of the cylinder (1) during its exhaust upstroke is minimized owing to an adjustment of the turbine pressure by means of an additional exhaust valve (4), called a “dynamic discharge valve”, optionally equipped with a downstream throttle valve (8) in order to continuously adjust the corresponding flow rate and, consequently, the pressure of the turbine unless the control of the dynamic discharge valve (4) is not variable itself.