Transient control of speed and torque on the testbed is becoming increasingly important for modern engine development. This paper describes the application of a modern control technique, Generalised Predictive Control (GPC) to this problem. By using system identification, coupled with the GPC design algorithm, the controller is automatically tuned by a computer. The best performance can then be obtained for each installation. The results presented show that, on a testbed with a standard eddy current dynamometer, tight control of transient speed and torque can be achieved using these techniques. This enables transient testing facilities to be made much more widely available.