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To quantify the fuel consumption and emissions improvements of Direct fuel Injection (DI), measurements were taken from a two-stroke motorcycle engine while operating in premixed, and direct injection mode burning propane. The part-load lean combustion limit was investigated for the DI technique in both premixed and DI modes. Results were compared to a one-dimensional Computational Fluid Dynamics (CFD) model of the engine. Results indicate that a highly stratified mixture can not be achieved due to poor mixing. The DI technique yields significant reductions in HC emissions, and significantly improved fuel economy, though not as good at Gasoline Direct Injection (GDI). Finally an economic analysis indicates that a gaseous fuel DI retrofit system represents a significant cost savings over a gasoline DI retrofit system.

It is difficult to obtain accurate fuel consumption data for privately owned in-use vehicles. This study aims to directly measure fuel consumption and the various parameters which affect fuel consumption from in-use vehicles via various methods. Motorcycle power demands were determined from measured frontal area, vehicle mass, rider and payload mass, tire pressure. Both worst case and best case scenarios of load, tire pressure and frontal area were measured for aerodynamic and rolling resistance via the roll-down technique. Measured data points for typical motorcycles fall within the established best- and worst-case scenarios, and an “average case” is selected for vehicle testing. Several common motorcycles models are tested for their fuel consumption at the established “average load” case. Additionally, this typical load case is coupled with the ECER40 drive cycle pattern for estimates of field fuel consumption from chassis dynamometer testing.

Existing drive cycles do not correlate well with actual drive cycles in developing countries due to differences in vehicle mixes, and traffic flow patterns. Several distinct drive cycles were identified in Malaysia namely the urban, suburban, rural, highway and delivery drive cycles. Several methods were used in generating drive cycles including direct observation, motorcyclist surveys, vehicle shadowing with on-board wheel speed measurement and data logging. These drive cycles were compared to existing European, United States, world harmonized motorcycle drive cycles and evaluated for fuel consumption. Results indicate that the Malaysian drive cycles are capable predicting actual vehicle fuel mileage within +/− 10% for a wide range of vehicles, while the European drive cycle results in a 20%deviation from the actual vehicle fuel mileage.