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Demonstrating the cost/benefits of technologies in the automotive sector is becoming very challenging because the benefits from technologies are sometimes of similar magnitude to testing precision. This paper aims to understand vehicle-borne imprecision and the effect of this on the quality of chassis dynamometer (CD) testing. Fuel consumption and NOx emissions precision is analyzed for two diesel vehicles with particulate filter and SCR systems. The two vehicles were tested on a high precision CD facility over the NEDC (New European Drive Cycle) and WLTC (World harmonized Light-duty Test Cycle) cycles. The CD base precision of testing was characterized between 0.6-3% depending on the cycle phase. A novel application of multi-variate statistical analysis was used to identify the factors that affected testing precision, allowing isolation of small differences that were not obvious when conducting cycle-averaged or cycle-phase-averaged analysis.

Nitrogen oxides emissions are an important aspect of engine design and calibration due to increasingly strict legislation. As a consequence, accurate modeling of nitrogen oxides emissions from Diesel engines could play a crucial role during the design and development phases of vehicle powertrain systems. A key step in future engine calibration will be the need to capture the nonlinear behavior of the engine with respect to nitrogen oxides emissions within a rapid-calculating mathematical model. These models will then be used in optimization routines or on-board control features. In this paper, an artificial neural network structure incorporating a number of engine variables as inputs including torque, speed, oil temperature and variables related to fuel injection is developed as a method of predicting the production of nitrogen oxides based on measured test data. A multi-layer perceptron model is identified and validated using data from dynamometry tests.

Exhaust Gas Recirculation (EGR) is widely used in IC combustion engines for diluting air intake charge and controlling NOx emission. The rate of EGR required by an engine varies by the speed and load and control of the right amount entering the cylinders is crucial to ensure good engine performance and low NOx emission. However, controlling the amount of EGR entering the intake manifold does not ensure that EGR rate will be evenly distributed among the engine's cylinders. This can many times lead to cylinders operating at very high or low EGR rates which contradictory can deteriorate particulate matter and NOx emission. The present study analyses the cylinder-to-cylinder EGR dispersion of a 4 cylinder 2.2L EUROV Diesel engine and its effects on the combustion stability. A 1D-3D coupling simulation is performed using GT-Power and STAR-CCM+ to analyze the effects of intake manifold geometry and EGR supply configuration on the EGR homogeneity and cylinder-to-cylinder distribution.