Search Results

A single-cylinder, 500cc research engine was tested under Spark-Ignition (SI) and Controlled Auto-Ignition (CAI) operation with similar load and speed conditions. Camshafts with low-lift and short duration, run with a negative valve overlap, were used to obtain CAI at wide open throttle. Two different camshaft profiles were tested in order to get a wide span of loads at 1200 and 2000rpm. The SI engine was Port Fuel-Injected (PFI) while the CAI engine was tested with both PFI and an Orbital Air-Assist Direct-Injection (DI) system. To reduce the high Indicated Specific Nitrogen Oxide (ISNOx) emissions at λ=1, 10% External Exhaust Gas Residuals (EEGR) was applied to the SI engine. EEGR reduced ISNOx emissions and there was slight reduction in ISFC. However, when the engine was tested in CAI mode, both ISNOx and ISFC were lower than the SI engine.

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.

This paper describes an inertial dynamometer system which has been applied to the testing of small two-stroke kart racing engines. The dynamometer incorporates a flywheel of appropriate moment of inertia to simulate the mass of a kart and driver. The test procedure involves measurement of the flywheel speed during an acceleration phase resulting from opening the throttle. Calculation of the instantaneous flywheel acceleration corresponding to each engine speed directly gives a measure of the torque and power characteristics. Performance results, including exhaust pressure traces, are presented from a series of tests conducted on a 100 cm3 kart engine. The results are compared with corresponding steady state measurements recorded on an eddy current dynamometer. In addition, the measured results are compared with predictions from a computer simulation.