A turbocharger having a variable-nozzle turbine, comprising: a turbine assembly comprising a turbine housing and a turbine wheel mounted in the turbine housing and connected to a rotatable shaft for rotation therewith, the turbine housing defining a chamber surrounding the turbine wheel for receiving exhaust gas and for supplying the exhaust gas to the turbine wheel, the turbine assembly defining a nozzle leading from the chamber radially inwardly to the turbine wheel; a compressor assembly comprising a compressor housing and a compressor wheel mounted in the compressor housing and connected to the rotatable shaft for rotation therewith; a variable-vane assembly comprising a annular nozzle ring and an array of vanes circumferentially spaced about the nozzle ring adjacent a first face thereof, and a unison ring that is rotatable about a central axis of the variable-vane assembly, the unison ring defining a plurality of recesses in a radially inner periphery of the unison ring, the vanes being disposed in the nozzle such that exhaust gas flows between the vanes to the turbine wheel, wherein each vane is joined to an axle that passes through a bearing aperture in the nozzle ring, wherein an end of each axle projects out from the bearing aperture at a second face of the nozzle ring opposite from said first face and is joined to a vane arm at a proximal end of the vane arm, wherein the vane arms have distal ends that are received respectively into the recesses in the radially inner periphery of the unison ring such that rotation of the unison ring about the central axis causes the vane arms to pivot the axles and thereby rotate the vanes between a fully open position and a fully closed position and intermediate positions therebetween for regulating exhaust gas flow to the turbine wheel; and a locking arrangement for locking the vanes in the fully open position, the locking arrangement comprising a plurality of locking tongues extending radially inwardly from the radially inner periphery of the unison ring, each said locking tongue being adjacent a respective one of the recesses in the radially inner periphery characterized in being positioned to contact a respective one of the vane arms at a location intermediate the distal end and the proximal end of the vane arm in the fully open position. a turbine assembly comprising a turbine housing and a turbine wheel mounted in the turbine housing and connected to a rotatable shaft for rotation therewith, the turbine housing defining a chamber surrounding the turbine wheel for receiving exhaust gas and for supplying the exhaust gas to the turbine wheel, the turbine assembly defining a nozzle leading from the chamber radially inwardly to the turbine wheel; a compressor assembly comprising a compressor housing and a compressor wheel mounted in the compressor housing and connected to the rotatable shaft for rotation therewith; a variable-vane assembly comprising a annular nozzle ring and an array of vanes circumferentially spaced about the nozzle ring adjacent a first face thereof, and a unison ring that is rotatable about a central axis of the variable-vane assembly, the unison ring defining a plurality of recesses in a radially inner periphery of the unison ring, the vanes being disposed in the nozzle such that exhaust gas flows between the vanes to the turbine wheel, wherein each vane is joined to an axle that passes through a bearing aperture in the nozzle ring, wherein an end of each axle projects out from the bearing aperture at a second face of the nozzle ring opposite from said first face and is joined to a vane arm at a proximal end of the vane arm, wherein the vane arms have distal ends that are received respectively into the recesses in the radially inner periphery of the unison ring such that rotation of the unison ring about the central axis causes the vane arms to pivot the axles and thereby rotate the vanes between a fully open position and a fully closed position and intermediate positions therebetween for regulating exhaust gas flow to the turbine wheel; and a locking arrangement for locking the vanes in the fully open position, the locking arrangement comprising a plurality of locking tongues extending radially inwardly from the radially inner periphery of the unison ring, each said locking tongue being adjacent a respective one of the recesses in the radially inner periphery characterized in being positioned to contact a respective one of the vane arms at a location intermediate the distal end and the proximal end of the vane arm in the fully open position.