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Measurement of sound intensity techniques has very good application in the source identification of a particular noise character. It has been applied effectively along with modal analysis and FE experimental excitation techniques to find out root cause of a particular noise character in small gasoline engine. A FEM shell model was used to make cylinder block and cylinder head model. FEM simulation was carried out which matched with experimental results. It helped to remove the noise character from engine. The other part of the paper describes the noise reduction of the crankcase cover used for the same motorcycle. It houses crankcase as well as two speed gearbox. The methodology involves very effective combination of experimental harmonic analysis, FE model with the shell element for the 3 piece crankcase cover, and experimental measurements. A particular sequence of this experimental techniques along with computer simulation techniques gives extremely good results.

Torsional and lateral bending vibrations of cylinder block have a large effect on engine noise. Cylinder block vibration not only causes noise to radiate from the cylinder block itself but it is also the major exciting force to the oil pan and timing belt cover. In order to reduce engine noise, it is important to completely understand the mechanism of cylinder block vibrations. An analysis is conducted using FEM and BEM to compute the influence of crankshaft torsional vibrations on cylinder block vibrations. A crankshaft system for a four cylinder automobile engine was used for analysis. Finite Element model of crankshaft is created using parametric modelling software developed based on ANSYS FEA software. Finite Element model of cylinder block, bearing cap, oil sump is also created using another parametric software developed based on ANSYS FEA software.