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In this paper we perform a validation study of a finite-volume model developed to predict the performance of a motorbike silencer. The computational setting has been defined to closely fit the tests conditions, obtained on a test-bench where the mass flow rate through the device is measured for several inlet-outlet pressure gradients. The comparison with the experimental measurements has shown that numerical data reproduce the effective trends of mass flow rate, although underestimation of 20% on average is present. Moreover, this discrepancy has shown to slightly increase with the raising of the overall pressure gradient. Neither the adoption of different mesh sizes nor computational settings for the turbulence modelling has allowed to obtain a reduction in the uncertainty of results. Therefore, the finite-volume model seems to be promising in the analysis of different design proposals while less effective in the prediction of the absolute performance of a motorbike silencer.

In all Ducati L-twins the crankshaft supports are rolling bearings. Due to the higher performance, compactness and lightness, the service life of the crankcase is becoming shorter and in future can become critical in the Ducati 999, the most powerful engine of the Borgo Panigale company. The engine block sidewalls must be strengthened in order to improve the reliability of the component. This can be done by reducing the size of the main bearing housings by the adoption of the plain bearings which have smaller radial dimensions. The stress field of the Ducati 999 crankcase in the two different configurations is calculated by means of the finite element method, applying the engine load in the critical conditions.