A turbocharger system comprising - an internal combustion engine and a turbocharger comprising - a turbine guided by the exhaust gases of said internal combustion engine, wherein said turbine has a variable geometry, being of a centripetal radial type that defines an axis of symmetry and comprises a rotor equipped with corresponding rotor blades, which are arranged radially, and a stator equipped with corresponding stator vanes, which are arranged circumferentially and radially and externally with respect to the rotor blades, and wherein said stator vanes are orientable, and comprising an annular, cylindrical sliding wall coaxial to the stator, which slides axially for varying an efflux section of said stator vane turbine, wherein said sliding wall comprises a hollow seat for each of said stator vanes, formed in the thickness of the sliding wall, to englobe at least partially said stator vanes during said sliding movement and wherein the turbocharger system comprises, in each of said hollow seats, a bushing, which has an outer shape complementary with said hollow seat and is rotatably associated to said hollow seat, and wherein said bushing has an inner slot having a shape complementary with one of said stator vanes so that said vane may slide axially therein; the turbine further comprising first means for controlling an orientation of said stator vanes and second means for controlling an axial position of said sliding wall and being characterized in comprising processing means configured to control said turbine such that in engine brake mode operation of the internal combustion engine the sliding wall is controlled to reduce the efflux section and increase the backpressure of the internal combustion engine up to a predefined limit threshold, and the stator vanes are oriented to obtain the maximum aerodynamic efficiency for the turbine, with a relative velocity (Vr) defining a zero or negative angle with respect to a radial direction of the rotor. - an internal combustion engine and a turbocharger comprising - a turbine guided by the exhaust gases of said internal combustion engine, wherein said turbine has a variable geometry, being of a centripetal radial type that defines an axis of symmetry and comprises a rotor equipped with corresponding rotor blades, which are arranged radially, and a stator equipped with corresponding stator vanes, which are arranged circumferentially and radially and externally with respect to the rotor blades, and wherein said stator vanes are orientable, and comprising an annular, cylindrical sliding wall coaxial to the stator, which slides axially for varying an efflux section of said stator vane turbine, wherein said sliding wall comprises a hollow seat for each of said stator vanes, formed in the thickness of the sliding wall, to englobe at least partially said stator vanes during said sliding movement and wherein the turbocharger system comprises, in each of said hollow seats, a bushing, which has an outer shape complementary with said hollow seat and is rotatably associated to said hollow seat, and wherein said bushing has an inner slot having a shape complementary with one of said stator vanes so that said vane may slide axially therein; the turbine further comprising first means for controlling an orientation of said stator vanes and second means for controlling an axial position of said sliding wall and being characterized in comprising processing means configured to control said turbine such that in engine brake mode operation of the internal combustion engine the sliding wall is controlled to reduce the efflux section and increase the backpressure of the internal combustion engine up to a predefined limit threshold, and the stator vanes are oriented to obtain the maximum aerodynamic efficiency for the turbine, with a relative velocity (Vr) defining a zero or negative angle with respect to a radial direction of the rotor.