A 1477K (2200°F) high work turbine designed to power the gas generator of an advanced variable capacity 683 kw (916 hp) turboshaft engine is described. The 2.27 kg/s (5.0 lbs/s) radial turbine was configured with a cooled movable sidewall nozzle capable of changing the stage flow capacity from 50 to 100 percent of maximum. The rotor was designed to be uncooled with a 4000 hour life and a duty cycle for a rotorcraft application. Overall performance test data were obtained in a turbine test rig that duplicated engine Reynolds numbers. Experimental results are presented showing the effects on performance of: 1) Changing flow capacity by moving the hub or shroud sidewall; 2) Vane sidewall leakage; 3) Vaneless space sidewall geometry; and 4) Nozzle cooling injection. The overall performance was evaluated over a range of pressure ratios and cooling flows and at equivalent speeds from 60 to 100 percent of design. Data are presented in the form of turbine flow, efficiency, work parameters and performance maps.