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This paper presents work performed to improve an engine's fuel economy by introducing ultrasonic atomization as the method of fuelling. An ultrasonic atomizer was added to the air intake path of a four stroke spark-ignited two-wheeler engine, replacing the conventional carburetor. Test results indicate that the engine BSFC reduced by around 20% due to lower pumping losses and lean operation facilitated by better fuel atomization. Less throttling also reduced the pressure difference between the air filter and combustion chamber, especially at lower speeds and low loads. This reduced exhaust gas dilution into the intake manifold and hence a rich mixture was not required for stable operation even at idling conditions. HC emissions are seen to be high and will need to be addressed, but NO emissions reduced significantly.

Every year, large numbers of two wheelers are sold in India and other Asian countries. A majority of these engines still tend to be carbureted due to cost and fuel quality issues. As an alternative to the carburetor, port fuel injectors (PFI) have started being introduced in the last few years for small two wheeler vehicles. Although PFI systems offer better metering of fuel and better transient response compared to carbureted systems, they are more expensive and require more power to pressurize the fuel. More importantly, wall film formation is observed in both the technologies, which reduces the effectiveness of the PFI system. Hence, a new technology is proposed which includes a PFI system along with an ultrasonic atomizer. The purpose of the proposed system is to improve the transient response and hence improve the fuel economy of gasoline engines and lower the emissions especially under cold conditions. The proposed concept was tested standalone on a laboratory setup.