Electronic Fuel System Development for Air-Cooled Motorcycles 2004-32-0059
Southwest Research Institute® (SwRI®) has developed electronic fuel injection (EFI) systems to be used on air-cooled motorcycle applications. In order to explore differences in application requirements between large and small displacement motorcycles, a large twin-cylinder, four-stroke, air-cooled motorcycle, and a small single cylinder, four-stroke, air-cooled motorcycle were utilized. The primary objectives of this study were to meet current and future emissions regulations for motorcycle exhaust emissions, to raise fuel economy, and to improve overall engine performance.
The EFI development required baseline testing, control system setup, design of intake system components, installation of sensors and control unit, fuel system integration, steady-state and transient calibration, fuel consumption development, emissions development, performance improvement, and acceleration testing. In order to perform all tests, a motorcycle chassis eddy-current dynamometer, a five-gas emissions bench, wide-range oxygen sensor, and fuel flow measurement equipment were used. A software tool, particularly designed for the custom electronic control unit (ECU), was used to perform all calibration work and record ECU related data.
Using a sophisticated EFI system offers precise control over the air/fuel ratio for each cylinder over the entire engine operation range. Additionally, the ignition timing and the timing of injection can be controlled by the EFI system. All steady-state and transient calibration tables were calibrated based on the results of conducted emissions, fuel consumption, and performance tests in order to improve performance while meeting the required emissions standards and improving the engine performance.
Integration of the EFI system resulted in the reduction of engine out emissions, an improvement in fuel economy, especially for the small displacement single cylinder engine, as well as improved engine output performance.