Heat is only what is making the gasses expand. Its the aerodynamic flow of the gasses across the turbine that does the work, not the heat.

A turbine is a turbine, they all work by the push of gasses flowing over the work surfaces, the temperature makes very little difference. Thats why a turbo will make the same boost just as easily with 600*f exhaust as it can with 1600*f exhaust.