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Engine and aftertreatment models have been developed in support of gasoline direct injection (GDI) engine development and aftertreatment system design. A brief overview of the engine models that were used to project emissions and fuel economy performance for the GDI engine is presented. Additionally, the construction and validation of a NOx trap aftertreatment model is described in considerable detail. The insights and increased understanding which have been gained regarding the trade-offs between engine out emission targets, aftertreatment performance, and emission constrained fuel economy benefits for direct injection gasoline engines are reviewed and discussed.

This paper describes the dynamometer development of a lightly stratified direct-injection spark-ignition engine. The engine was designed for stratified charge operation at speeds and loads below 2000 RPM, 2 bar BMEP. Test results detailed in this report include evaluation of part-load stratified-charge, part-load homogeneous-charge, and WOT operation. The program had aggressive goals in improving WOT performance and part-load fuel consumption compared to a baseline PFI engine while meeting Stage V emissions levels. Mini-map analysis of the engine data indicated that the engine was able to meet the emissions and fuel consumption goals.