Search Results

The objective of this project was to develop a bolt-on natural gas conversion kit for the 6V-71 two stroke diesel engine used in most transit coach in Canada. For various reasons it was decided to try to improve on an existing mechanical conversion system instead of starting from new. An electronic controller and various other modifications were used to obtain better engine reliability and efficiency. This paper describes the final system and present both performance and emissions results obtained from dynamometer testing and also results of field testing.

This paper describes the results of a research undertaken at Ecole Polytechnique in order to improve the combustion characteristics of natural gas used as an alternate fuel in a spark ignition engine originally designed for gasoline. Due to the physical characteristics of NG, users may experience a power loss ranging from 10 to 20% of original power. Since, for some applications, this loss is not acceptable, means to enhance combustion must be found. In this search for more power, various possibilities may be explored but, in this particular research, mixtures of NG and gasoline were supplied to a single cylinder engine in order to improve its performance: since the flame speed is faster in gasoline - air mixtures than in methane - air mixtures it was postulated that methane -gasoline - air mixtures might have better combustion characteristics.

This report is part of a research program carried out at Ecole Polytechnique de Montreal and aimed at the use of natural gas in automobiles. A computer simulation, modeling the behavior of the conventional equipment (conversion kit) used to convert a gasoline engine to natural gas, was carried out under varying temperature and storage pressure conditions. The results of this study clearly indicated the need for an approach which would compensate for the variations of densities of both air and fuel. The design of an electronically controlled injection system with enough flexibility to allow its use on most engines with only minor modifications was thus undertaken. The ultimate goal of this research is to operate the engine with a closed loop fully auto-adaptative system but the first step in the design was limited to an open loop semi-empirical system that has shown good preliminary test results.