Current engine development processes typically involve extensive steady-state and simple transient testing in order to characterize the engine's fuel consumption, emissions, and performance based on several controllable inputs such as throttle, spark advance, and EGR. Steady-state and simple transient testing using idealistic load conditions alone, however, is no longer sufficient to meet powertrain development schedule requirements. Mapping and calibration of an engine under transient operation has become critically important. And, independent engine development utilizing accelerated techniques is becoming more attractive.
In order to thoroughly calibrate new engines in accelerated fashion and under realistic transient conditions, more advanced testing is necessary. Recent studies have indicated that such powertrain testing requires four critical elements: (1) mathematical models of the engine, transmission, and/or vehicle subsystems, (2) a real-time operating system and hardware, (3) an AC dynamometer, preferably a low-inertia, high-power dynamometer system, and (4) sophisticated dyno control algorithms for applied load and inertia simulation. This paper briefly describes an implementation of these elements and provides the results obtained in an engine test cell at Southwest Research Institute.