The Problems of Noise of Engines in Different Vehicle Groups

The paper classifies all current automotive engines into four distinct groups relative to engine usage and vehicle noise legislation.

The noise characteristics of the engines in each group are widely different except that at their maximum rated speeds the overall noise levels approach the same value

The sources of noise rank in different importance according to the size and type of engine. Therefore quiet engine design must also vary.

The importance of mechanical noise is emphasised and it is considered that this source could be a limiting factor to future low noise engines.