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 for receiving exhaust gas and for supplying the exhaust gas to the turbine wheel, the turbine assembly defining a nozzle leading from the chamber generally 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 center housing connected between the compressor housing and the turbine housing, the center housing defining a radial reference surface that faces radially outwardly and an axial reference surface that faces axially toward the turbine wheel; and a variable-nozzle cartridge connected between the center housing and the turbine housing and comprising an assembly of a generally annular nozzle ring and an array of rotatable vanes circumferentially spaced about the nozzle ring and disposed in the nozzle for regulating exhaust gas flow to the turbine wheel, wherein the nozzle ring at a radially inner periphery thereof defines a radial reference surface that faces radially inwardly and opposes the radial reference surface of the center housing, and an axial reference surface that faces axially away from the turbine wheel; and an insert defining a nozzle portion that is axially spaced from the nozzle ring such that the vanes extend between the nozzle ring and the nozzle portion, a plurality of spacers being connected between the nozzle ring and the nozzle portion of the insert; and a heat shroud and spring assembly disposed in a space bounded between the radially inner periphery of the nozzle ring, the turbine wheel, and the center housing, the heat shroud and spring assembly comprising a heat shroud and a spring formed as two discrete parts, the heat shroud comprising an annular non-flat disk-shaped part and the spring comprising an annular non-flat disk-shaped part, the heat shroud and the spring abutting each other at radially outer and radially inner peripheral regions thereof and being spaced apart over an intermediate region between said radially inner and radially outer peripheral regions so as to define a dead space between the heat shroud and the spring that is sealed off from exhaust gases surrounding the heat shroud and spring assembly. 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 for receiving exhaust gas and for supplying the exhaust gas to the turbine wheel, the turbine assembly defining a nozzle leading from the chamber generally 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 center housing connected between the compressor housing and the turbine housing, the center housing defining a radial reference surface that faces radially outwardly and an axial reference surface that faces axially toward the turbine wheel; and a variable-nozzle cartridge connected between the center housing and the turbine housing and comprising an assembly of a generally annular nozzle ring and an array of rotatable vanes circumferentially spaced about the nozzle ring and disposed in the nozzle for regulating exhaust gas flow to the turbine wheel, wherein the nozzle ring at a radially inner periphery thereof defines a radial reference surface that faces radially inwardly and opposes the radial reference surface of the center housing, and an axial reference surface that faces axially away from the turbine wheel; and an insert defining a nozzle portion that is axially spaced from the nozzle ring such that the vanes extend between the nozzle ring and the nozzle portion, a plurality of spacers being connected between the nozzle ring and the nozzle portion of the insert; and a heat shroud and spring assembly disposed in a space bounded between the radially inner periphery of the nozzle ring, the turbine wheel, and the center housing, the heat shroud and spring assembly comprising a heat shroud and a spring formed as two discrete parts, the heat shroud comprising an annular non-flat disk-shaped part and the spring comprising an annular non-flat disk-shaped part, the heat shroud and the spring abutting each other at radially outer and radially inner peripheral regions thereof and being spaced apart over an intermediate region between said radially inner and radially outer peripheral regions so as to define a dead space between the heat shroud and the spring that is sealed off from exhaust gases surrounding the heat shroud and spring assembly.