The Stratified Charge Glowplug Ignition (SCGI) Engine with Natural Gas Fuel

The objective was to demonstrate the feasibility of operating a natural gas two-stroke engine using glow plug ignition with very lean mixtures. Based on the results obtained, the term SCGI (stratified charge glow plug ignition) was coined to describe the engine. An JLO two-stroke diesel engine was converted first to a natural gas fueled spark-ignited engine for the baseline tests, and then to an SCGI engine. The SCGI engine used a gas operated valve in the cylinder head to admit the natural gas fuel, and a glow plug was used as a means to initiate the combustion.

The engine was successfully run, but was found to be sensitive to various conditions such as the glow plug temperature. The engine would run very lean, to an overall equivalence ratio of 0.33, offering the potential of good fuel economy and low NO_x emissions. Fuel economy was compared to other natural gas engines and found to be not so good on a brake specific basis; however there was not time for much development work, and the potential for good economy still exists. It was recommended that exhaust emissions be measured.