Prediction of tractor engine performance using OECD Standard Test data

Two models of diesel engine performance have been developed which will accurately predict the performance of an engine across its operating range. One model predicts torque and fuel consumption from engine speed and throttle setting and the other predicts torque from engine speed and fuel consumption. Both models are based on universal functions which involve coefficients calculated from data measured by p.t.o. testing of the particular engine, using a test sequence which provides data broadly spread across the engine performance space. This paper investigates whether sufficient data are available from the OECD Standard Test to calibrate these models, without the necessity for further p.t.o. testing of each engine type. The OECD Standard Test is used as the basis of the investigation because it incorporates more data than the Nebraska Test. It is shown that there are insufficient data available to enable the p.t.o. torque and fuel consumption to be reliably predicted from engine speed and throttle setting, but that it is possible to use these data to predict accurately either p.t.o. or engine torque from engine speed and fuel consumption. It is necessary that results of the Optional Test (with the engine separated from the tractor) are available to be able to use either model. It is also proposed that consideration should be given to modifying the standard tractor test procedures so that sufficient data are available to enable models such as these to be used with confidence in predicting engine and p.t.o. performance throughout the operating range of the engine.