The control of chassis dynamometer fuel consumption testing noise factors and the use of response modelling for validation of test repeatability

Abstract

The research described in this paper was aimed at demonstrating the implementation of statistically derived tolerances to so-called ‘noise’ factors that cause imprecision in the vehicle fuel consumption during chassis dynamometer testing. These tolerances were derived from previous work carried out by one of the authors co-workers and were set to achieve a repeatability target of 0.5% coefficient of variation in the vehicle fuel consumption. This target was successfully achieved during a test programme to determine the fuel consumption benefit of two candidate engine oils over production engine oil using a 1.0 l gasoline passenger test vehicle. Regression response modelling was used to determine whether the recorded variability was correlated with the variability in the vehicle fuel consumption and it was found that all the measured test noise factors were adequately controlled. A universal methodology is proposed for the use of the response modelling technique to verify adequate control of known noise factors and to allow for corrections to the vehicle fuel consumption to be performed where factors have not been adequately controlled, without the need to complete additional testing.