Performance Analysis of Motorcycle Mufflers

The presentation to follow introduces an analytical tool in which calculations for exhaust flow resistance (due to flow resistance), an important element in combustion engine output performance, have been defined and combined with theoretical noise reduction calculations to approximate the actual exhaust flow resistance and noise reduction level of given engine and muffler combinations. These calculations take factors such as muffler shape, exhaust gas flow velocity, and sound-absorbing materials into consideration.

In developing this method, tests were conducted in which exhaust gas pressure waveforms were analyzed in terms of frequency, velocity, and pressure and the initial engine output sound was calculated. Then the calculated noise reduction performance of a given muffler was subtracted from that value at specific frequencies (corresponding to a given engine speed) to determine the theoretical net exhaust noise.