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2-stage supercharging applied to HSDI Diesel engines is a promising solution for enhancing rated power, low end torque, transient response and hence the launch characteristics of a vehicle. However, a trade-off is required to match some conflicting issues, i.e. overall dimensions, cost, emissions control and performance. The outcome strongly depends on the specific constraints and goals of the project. In the paper, reference is made to 2.8L, 4 cylinder in-line unit produced by VM Motori (Cento, Italy), equipped by a standard variable geometry turbocharger. A 1D thermo-fluid-dynamic model of the Euro V version of the engine was built and calibrated against experiments at the dynamometer bench, at both full and partial load.

One dimensional CFD codes are standard tools for engine development, in particular for the optimization of intake and exhaust systems. However, the accurate prediction of both engine brake performance and acoustic outputs is not that trivial. A quite critical issue is the modeling of complex engine components, such as air cleaners, plenums, exhaust junctions, silencers, etc. A trade-off is required in order to balance the accuracy of the acoustic analysis and the computational cost, particularly when DOE techniques have to be applied. In this paper a methodology for an integrated acoustic and performance analysis of a high performance SI engine is described. An engine simulation model has been built by using a commercial software, and it has been validated against experiments, finding a good agreement. It is remarked that the measurements of both acoustic and engine performance parameters are taken by using standard facilities and equipment, no anechoic test bench is required.