The Quantification and Reduction of Piston Slap Noise

Abstract

Recent advances by engine and vehicle manufacturers in the reduction of overall noise levels have resulted in piston slap noise becoming more intrusive and its reduction increasingly important. At AE an essential part of a larger programme aimed at achieving this objective has been to develop a technique to assess piston noise in gasoline engines. The paper describes this technique and its application to investigate the effect of piston clearance and bore ovality. The technique may be applied to engines in development without recourse to internal instrumentation and correlates well with the result of listening panels.