A turbocharger configured to receive an exhaust gas stream from an engine configured to operate over a range of standard operating conditions, and to compress input air into a pressurized air stream, comprising: a housing including a turbine housing; and a rotor configured to rotate within the housing along an axis of rotor rotation, the rotor including an axial turbine wheel, a compressor wheel, and a shaft extending along the axis of rotor rotation and connecting the turbine wheel to the compressor wheel; wherein the turbine wheel is configured with a hub, and with a plurality of axial turbine blades configured to drive the rotor in rotation around the axis of rotor rotation when the turbocharger receives the exhaust gas stream from the engine, the blades having an axially upstream edge, an axially downstream edge, a hub end, and a tip end opposite the hub end; wherein the compressor wheel is configured to compress the input air into the pressurized air stream when the rotor is driven in rotation around the axis of rotor rotation by the turbine wheel; wherein the turbine housing forms an inwardly spiraling turbine primary-scroll passageway that turns in an axial direction and the inwardly spiraling turbine primary-scroll passageway has a primary-scroll inlet port with a centroid radially external to the axially upstream ends of the blades; wherein the trailing edge has a radius at the hub end and a radius of the tip end; wherein the radius at the hub end of the turbine wheel trailing edge is no more than 60% of the radius of the tip end of the turbine wheel trailing edge; wherein the turbine wheel hub is radially larger at the blade leading edges than it is at the blade trailing edges, characterized in that: the turbine wheel hub is radially larger at an intermediate axial location between the leading edges and the trailing edges than it is at either the leading edges or the trailing edges, and the turbine blades each have a blade turning angle at an intermediate radius between the hub and the tip that is greater than or equal to 80 degrees. a housing including a turbine housing; and a rotor configured to rotate within the housing along an axis of rotor rotation, the rotor including an axial turbine wheel, a compressor wheel, and a shaft extending along the axis of rotor rotation and connecting the turbine wheel to the compressor wheel; wherein the turbine wheel is configured with a hub, and with a plurality of axial turbine blades configured to drive the rotor in rotation around the axis of rotor rotation when the turbocharger receives the exhaust gas stream from the engine, the blades having an axially upstream edge, an axially downstream edge, a hub end, and a tip end opposite the hub end; wherein the compressor wheel is configured to compress the input air into the pressurized air stream when the rotor is driven in rotation around the axis of rotor rotation by the turbine wheel; wherein the turbine housing forms an inwardly spiraling turbine primary-scroll passageway that turns in an axial direction and the inwardly spiraling turbine primary-scroll passageway has a primary-scroll inlet port with a centroid radially external to the axially upstream ends of the blades; wherein the trailing edge has a radius at the hub end and a radius of the tip end; wherein the radius at the hub end of the turbine wheel trailing edge is no more than 60% of the radius of the tip end of the turbine wheel trailing edge; wherein the turbine wheel hub is radially larger at the blade leading edges than it is at the blade trailing edges, the turbine wheel hub is radially larger at an intermediate axial location between the leading edges and the trailing edges than it is at either the leading edges or the trailing edges, and the turbine blades each have a blade turning angle at an intermediate radius between the hub and the tip that is greater than or equal to 80 degrees.