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It developed a design and construction methodology of a stratified charge torch ignition system for an Otto engine aiming fuel consumption and pollutant emission reduction. The torch ignition system is made of a combustion pre-chamber equipped with a direct fuel injector, an air injector and a spark plug. Fuel is directly injected in the pre-chamber aiming the formation of a lightly rich air fuel mixture. The combustion process starts in the pre-chamber and as the pressure rises, combustion jet flames are produced through interconnection nozzles into the main chamber. The high thermal energy of the jet flames reduces the combustion time, increases the combustion efficiency and allows the engine to efficiently burn lean air fuel mixture of several kinds of fuel in the main chamber, even those that are difficult to ignite. After the combustion takes place in the pre-chamber, air is also injected to help the exhaust process of the combustion products of the previous cycle.

The present work aims to analyze a torch ignition system running on lean homogeneous charge, adapted to an Otto cycle multi-cylinder engine. The main objective is to maximize engine efficiency by means of redesigning the ignition system adapting a pre-chamber to the main combustion chamber. This new ignition system allows reducing its IMEP covariance for leaner mixture operation due to the increase of ignition energy availability during the kernel formation. The engine used in this research is a commercial sixteen valve, four cylinders in line with cubic capacity of 1600 cm3. The performance date of baseline engine operating stoichiometrically were used as a reference for the comparison with torch ignition engine output running from stoichiometric mixture to its leaner operational limit. The brake mean effective pressure was maintained constant in all test configurations in order to make possible to compare engines thermal efficiency.