Modern turbocharged diesel engines employ exhaust driven turboblowers operating at high speeds up to 100,000 rpm. The performance assessment of such units demands precise and controllable power absorption and torque measurements at these very high rotational speeds. Additionally the parameters, speed, mass flow, static and dynamic pressures and temperatures must be measured. The turbine power absorption and torque measutement present unique problems. The remaining parameters may present some difficulties but generally the problems are not so great. The design of a high speed dynamometer and the development problems encountered are described. The dynamometer has been used to establihs the performance characteristics of a C. A. V. 01 turbocharger and these are reported.