Acoustic Tuning of the Intake and Exhaust Systems of a 4-Stroke Motorcycle Engine

Abstract

This project details the use of engine modeling software to inform acoustic optimization of the intake and exhaust system parameters of a single cylinder 4-stroke motorcycle engine. Acoustic pressure waves in the gases of the intake and exhaust systems of an internal combustion engine have a profound effect on the performance of the engine. Therefore, the acoustic properties of the exhaust and intake systems depend highly on the design parameters of these systems. Optimization of high engine speed power output through variation of engine ducting parameters was accomplished through software simulation and optimization. The acoustically tuned arrangements include a straight exhaust pipe, a curved exhaust pipe, an intake duct, and a diffuser. Power benefits were observed from tuning each of these arrangements. Comparison to empirical methods for selecting ducting parameters showed empirical methods to be unreliable. Pressure profiles generated by the simulation software were used to correlate performance gains to their acoustic causes.