Investigations on performance and emissions of a two-stroke SI engine fitted with a manifold injection system

Simple and cost effective electronically controlled injection systems have to be developed to combat the problem of urban pollution. In this work an electronically controlled fuel injection system developed in the Internal Combustion Engine Laboratory of Indian Institute of Technology Madras has been tested in detail on a two-stroke SI engine. The system is fitted on the intake manifold of a single cylinder, air cooled two-stroke scooter engine. Tests have been done at 3000 rpm and 4000 rpm at different throttle positions. The optimum injector pulse widths for thermal efficiency, lowest HC emissions and highest power are all different. The maximum brake thermal efficiency values are 22.6% and 23% at 3000 and 4000 rpm respectively. At a power output of 3 kW and 4000 rpm the brake thermal efficiency is about 21% for the carbureted engine. It increases to 23% with the fuel injection system. HC emissions are considerably lower than the carbureted version at all operating conditions and speeds. The engine can work with leaner mixtures with the injection system in general as compared to the carburetor. The maximum power increases with the injection system. The developed system can be used for mapping the engine for the development of software for injection system control.