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This paper describes the process used to characterise an exhaust after treatment designs while using spark retard and lean fuel operation during a cold start on a Euro 96 drive cycle using a dynamic dynamometer to simulate a vehicle. It is well understood that spark retard and lean fuel operation achieve faster catalyst light off times but usually at the cost of driveability. This study defines the operating envelope for both reduced emissions and vehicle driveability. A design of experiment methodology was employed to characterise the system and produce models that were used to perform a trade off between driveability and reduced emissions for a given hardware configuration. Statistical techniques were utilised to select the best vehicle calibration

The paper describes the assessment and testing of two high speed diesel engine structure modifications designed to reduce noise. The modifications tested are a five main bearing version of a standard three main bearing engine and the addition of a sump plate. The results indicate that it is difficult to assess the running engine vibration and noise characteristics using modal analysis techniques but that this is possible when using the banger test techniques. It is shown that noise reductions up to some 4.0 - 5.0 dBA can be achieved both on the test bed and in the vehicle application.