Combustion Efficiency and Sound Attenuation as Affected by Muffler Design

This paper identifies some of the environmental issues associated with sound attenuation of exhaust notes generated by internal combustion racing engines. It points to how sound abatement relates to overall engine combustion efficiency or power.

Historically, there has not been widespread concern about environmental impact of unabated exhaust noise produced in various forms of motorsports. Today, this is changing. In the interest of maintaining acceptable levels of power from muffled racing engines, a technology is emerging that focuses on the relationships between combustion efficiency and exhaust noise reduction.

Through the combined use of engine cycle analysis (ECA) and spectrum analysis, this paper discusses how these two areas of data acquisition and their application are leading to a reduction in the potential damage to human hearing, not to the significant detriment of race car performance.