Heavy-duty LNG

This article focuses on the natural gas advocates who have set their sights on the diesel engine, and some of their new ideas are getting a workout in California. Otto-cycle engines fueled by natural gas are common in cities as the operators of buses and other vehicle fleets try to keep emissions in check. Natural gas mixes with air before it enters the cylinder. An electronically controlled injector introduces a small amount of diesel fuel at the end of the compression stroke to begin ignition. According to Caterpillar, more than 85 percent of the fuel consumed can be natural gas in some applications. Cummins Westport Inc., Vancouver, BC, is testing a 400-hp diesel engine that burns natural gas. The system injects diesel as a pilot and then follows it with natural gas. Electronic controls determine the timing and quantity of natural gas.