Investigations on Influence of Engine Block Design Features on Noise and Vibration

The engine is the most important source of noise and vibration in a passenger car. Together with the oil pan the engine block in general radiates more than 50% of the total engine noise. Additionally structure-borne noise is transferred from the block through the engine mounts into the car body.

All design features, which influence the structural integrity of the engine block, will therefore have an impact on the customer perceived noise and vibration behaviour of the vehicle.

In order to develop an engine block towards a good noise and vibration performance, the first design decisions at the begin of a new engine programme should support this goal. This will facilitate the further development later on.

This paper outlines some possibilities of computation and a testing method applicable in an advanced phase to evaluate different engine block design features without having either the complete engine or even the final design of the engine block. Results indicating the influence of an open top deck as well as several designs of main bearing supports - cross-bolting and bridging of main bearing caps and a combination of both - are presented.