Abstract
The paper describes an investigation of the influence of belt design on the discharge process of a two-stroke cycle engine. Theoretical methods are developed for calculating the pressure changes in the cylinder, exhaust belt and pipe. A comprehensive experimental investigation of ten exhaust-belt configurations is then described. Pressure measurements were taken in the cylinder, belt and pipe. The experiments showed that the pressure was not uniform within the belt and decreased from the belt to the pipe. It was shown that an increase in belt size reduced the restrictive effects of a belt, shortened the blowdown time and increased the pulse amplitude in the exhaust pipe. There was an optimum belt size above which no further improvement was obtained unless the belt profile was altered, at this size the belt could be made within the normal engine dimensional limits. Data are given for designing exhaust ports and belts based on these experiments. The detailed development of the boundary equations for the gas exchange process is given in an appendix.

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