Couplings used for connecting engines to dynamometers can be subjected to torsional loads exceeding the design point unless precautions are implemented. The manufacturer's guidelines cannot alone predict a successful installation. A survey of the problems and solutions, as they apply to the modern high MEP engines, is presented. A wide range of testing speeds is possible with the appropriate combination of engine, coupling and dynamometer. The calculation of resonance conditions and practical guide for the selection and operation of a test set-up are presented.