The Effect of Combustion System on Engine Noise

The effects of using different combustion systems on engine noise are reviewed including an examination of noise reduction methods such as shielding, enclosure and structural modifications. Comparisons are made of direct injection and indirect injection systems and a new noise prediction formula for IDI engines is proposed.

The use of turbocharging is examined and the limiting effects of mechanical noise noted. The variation of exhaust emission levels with reduction of combustion noise is included.