The improvement of computer simulation packages with experimentally validated sub-models has benefited the engine designer in reducing development time and costs. Such packages offer invaluable information regarding the internal gas dynamics and gas exchange characteristics.
Presented are measured dynamometer results of a RS Honda 125 cm3 two-stroke single-cylinder motorcycle grand prix road-racing engine operating at full throttle from 9000 rev/min to 13000 rev/min. The engine is instrumented to provide in-cylinder and exhaust pipe pressure crank-angle histories.
All relevant engine geometry, discharge coefficients, scavenging characteristics and combustion data are used to simulate the engine using a one-dimensional (1-D) engine simulation package. In-cycle crankshaft angular velocity fluctuations are also considered. Performance parameters such as power, BMEP and delivery ratio, together with pressure diagrams are compared to the measured data. In addition, exhaust pipe changes are modeled and also compared to measured results.
Overall, the simulation package, using crankshaft speed fluctuations, is demonstrated to show excellent ability to predict the operating characteristics of a high performance two-stroke engine over the entire speed range and its use as a valuable design tool is established.