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With the introduction in Europe of drive cycles such as RDE and WLTC, transient emissions prediction is more challenging than before for passenger car applications. Transient predictions are used in the calibration optimization process to determine the cumulative cycle emissions for the purpose of meeting objectives and constraints. Predicting emissions such as soot accurately is the most difficult area, because soot emissions rise very steeply during certain transients. The method described in this paper is an evolution of prediction using a steady state global model. A dynamic model can provide the instantaneous prediction of boost and EGR that a static model cannot. Meanwhile, a static model is more accurate for steady state engine emissions. Combining these two model types allows more accurate prediction of emissions against time. A global dynamic model combines a dynamic model of the engine air path with a static DoE (Design of Experiment) emission model.

Compared to conventional homogeneous direct injection or port-fuel injected engines, the second generation, spray guided, direct injection engine (SGDI) has the potential for significantly improved fuel economy during part load stratified charge operation. Multiple fuel injection strategies can be utilised to increase the unthrottled operating range, leading to further improvements in fuel economy. However, careful optimisation of these strategies is essential to ensure that benefits are maintained whilst further minimising emissions within combustion stability limits and consumer driveability demands. The effects of multiple injection strategies upon fuel consumption, emissions and combustion stability were investigated in a single cylinder Ricardo Hydra engine with a spray guided combustion system. An outwardly opening piezoelectric actuated injector was employed. The fuel injection strategy utilised up to five injections per engine cycle.

This paper describes an investigation of emissions from an engine featuring variable valve timing, a swirlcontrol valve and exhaust gas recirculation. Design of experiments has been used to model the response of hydrocarbons and other emissions to the engine operating variables. The experiments identified the potential of VVT for simultaneous NOx, and HC reduction. The type of experiment employed was the Central Composite Rotatable Design; this is a fractional factorial design that maximises the amount of information obtained from a minimal number of test runs. A Fast Response Flame Ionisation Detector has been used to clarify the reasons for the effect of inlet and exhaust VVT on hydrocarbons.