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Boosting technologies have been key enablers for automotive engines development through downsizing and downspeeding. In this situation, numerous multistage boosting systems have appeared in the last decade. The complexity arising from multistage architectures requires an efficient matching methodology to obtain the best overall powertrain performance. The paper presents a model aimed to choose the best 2-stage boosting system architecture able to meet required criteria on boosting pressure, EGR ratios for both short and long route loops while respecting the engine thermo-mechanical limits such as in-cylinder pressure, compressor outlet temperature and exhaust manifold temperature. The model includes filling-and-emptying 0D elements together with mean value. The engine model is set in a way that, for given requirements and boosting system layout, calculates in seconds if the requirements will be achieved and the position of variable geometry, waste-gate, EGR and bypass valves. The model is thus inversed thanks to a new representation of turbine maps that converts the classical iterative matching procedure in straight forward. The model can be also used in a predictive manner to calculate the engine transient response. The model has been calibrated to 3 different turbocharged diesel engines. The model gives good results provided that wave effects are not important. This is the case of compact exhaust manifolds, typically used in turbocharged diesel engines, below 3500 rpm. Tuned intake air lines can be taken into account through a tuning parameter affecting boosting pressure. An example is given in the paper for the matching procedure in a 2-stage, double route EGR, including steady and transient results.

Nowadays, internal combustion engines developments are focused on efficiency optimization and emission reduction. Increasing focus on world hamonized way to determine the performance and emissions on WLTP cycles is demanding to optimize the engines within transient operations. To achieve these, downsized or downspeeded engines are required which can reduce fuel consumption and CO 2 emission. However, these technologies ask for efficient charging system. This paper consist of study of diffrent boosting architectures(single stage and two stage) with combination of diffrent charging system like super-chatgers, e-boosters etc. A parametric study is been carried out with a 0D engine model to analyze and compare diffrent architectures on same base engine. The impact of thermomechanical limits, turbo sizes and other engine development options characterizations are proposed to improve Fuel consumption, maximum power and performance of the downsized/downspeede diesel engines during the transient operations.