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Steady state mapping is fundamental to optimizing IC engine operation. Engine variables are set, a predefined settling time elapses, and then engine data are logged. This is an accurate but time consuming approach to engine testing. In contrast the sweep method seeks to speed up data capture by continuously moving the engine through its operating envelope without dwelling. This is facilitated by the enhanced capability of modern test rig control systems. The purpose of this work is to compare the accuracy and repeatability of the sweep approach under experimental conditions, with that of steady state testing. Limiting factors for the accuracy of the sweep approach fall into two categories. Firstly on the instrumentation side - transducers have a characteristic settling time. Secondly on the engine side - thermal and mechanical inertias will mean that instantaneous measurements of engine parameters differ from the steady state values.

Electric coolant pumps for IC engines are under development by a number of suppliers. They offer packaging and flexibility benefits to vehicle manufacturers. Their full potential will not be realised, however, unless an integrated approach is taken to the entire cooling system. The paper describes such a system comprising an advanced electric pump with the necessary flow controls and a supervisory strategy running on an automotive microprocessor. The hardware and control strategy are described together with the simulation developed to allow its calibration and validation before fitting in a B/C class European passenger car. Simulation results are presented which show the system to be controllable and responsive to deliver optimum fuel consumption, emissions and driver comfort.