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An upgraded vehicle fuel consumption/emission test facility is shown to be able to simulate on-road performance of cars up to wide open throttle operation. A procedure is described which permits dynamometer loads to be set so as to replicate the on-road, steady speed fuel consumption of each vehicle tested. A test program involving five driving cycles (schedules), three US and two Australian, and a range of other manoeuvres has been devised, to describe a wide range of on-road driving. The tests last one week and have been carried out on a fleet of almost 40 cars. Fuel and emission data has been logged at every half second interval of the tests. The overall test results only have been reported here. It is shown that there is considerable variability in the response of individual cars to changed test cycle. For the Australian test cycle fuel consumption is typically 15% higher than to US 75 FTP city test schedule.

A high speed research engine has optical access to over 80% of the combustion chamber volume through a piston with a quartz window. The engine has been used to study the effect of swirl on the spark-ignited combustion by means of high speed photography and analysis of combustion-time data. Results over the speed, swirl and mixture strength range show the flame travel derived from the pressure to agree with the measured flame travel to within 3% on average. Turbulent to laminar flame speed ratios as high as 45 occur under high swirl conditions. However it was not possible to find a predictive model which could explain the turbulent flame speed in terms of engine design variables.