Development of a 2-Stroke CNG Engine for 3-Wheeler Vehicle for the Indian Market

In recent years the Government of India has supported the use of Compression Natural Gas (CNG) in public and private vehicles. One of the ways to reduce emission is the use of alternative fuels. Among alternative fuels, Compressed Natural Gas (CNG) is one of the most promising mainly because of its low exhaust emissions. Numerous studies about CNG use in car and bus engines have been published extensively in the last two decades. The applications of CNG to bi-fuel or mono fuel engines have been tried all over the world at this time. However detailed study of 2 stroke 3 wheeler CNG engine has not been conducted so far. This paper describes development of a bi-fuel (CNG/Gasoline) single cylinder air cooled 200 cc, 2 stroke engine for 3 Wheeler application. This engine is an air cooled SI engine converted to operate on CNG fuel with electronic ignition system. An additional feature is the ability to change the spark ignition timing w.r.t. speed and type of fuel selected. The engine variables optimized included the compression ratio and the Ignition timing. The spark plug, lubrication oil, Cat-Con, First stage and second stage CNG pressure regulators , Gas-air mixer, Venturi size and power screw was some of the hardware selected and optimized suitable to CNG operation without compromising the base petrol performance. It was observed that the induction system optimization plays an important role in meeting the power performance and THC emission targets due to scavenging. Engine was optimized with a three-way Palladium based catalytic converter (instead of Pt based Cat Con) to meet proposed BS-III norms. This paper presents some of the experimental results obtained in this study.