‘Smokeless’ Diesel Engine to Be Tested in Southland

Times Staff Writer

Thick, black truck exhaust, as much a part of the Southern California experience as sunshine and sea breezes, could one day become a thing of the past.

Navistar International Corp., the Chicago conglomerate that builds International trucks, will begin testing the nation’s first “smokeless” diesel engine in Southern California sometime during the next year, the company said Wednesday at a trade show in Anaheim.

The new design, called “Smokeless 94,” emits almost clear exhaust because it burns fuel more efficiently than the traditional diesel engines that power most big trucks, Navistar said.

Although the company had several prototypes on display at the International Truck Show, the engines will not be released commercially until 1994. The design must still be tested on the road by truckers, the firm said.


Navistar increased the engine’s efficiency by boosting cylinder pressure to unusually high levels and designing a new type of piston, said James McCandless, a Navistar vice president who headed research on the engine.

Many of the nation’s largest truck makers have been experimenting with more efficient diesel engines for several years to meet tougher clean air standards scheduled to take effect in 1991, said Arthur G. Davis, an auto industry analyst at Prescott, Ball & Turben, a New York brokerage.

So far, though, most improvements have involved filtering exhaust fumes more effectively, rather than burning fuel more efficiently, Davis said. Other companies have designed “particulate traps” that can filter exhausts of engines now in use.

McCandless said particulate filters are less fuel efficient than an engine with little black exhaust, and are inconvenient because they must be regularly cleaned of carbon.


Even so, the Navistar design must be tested before its commercial potential can be gauged, Davis said.

“Navistar is first with this engine, but there’s no magic formula for success, because higher pressure means more wear,” Davis said. “A trucker wants to know whether the engine is durable before he’ll buy it, and that’s something they’ll have to test.”

Navistar, the nation’s leading manufacturer of large and medium-size trucks, said it has spent $20 million per year on research in the last few years to develop the engine.

The firm said it chose Southern California for testing because the engine uses catalytic converters that are damaged by high levels of sulfur contained in diesel fuel sold in other states. California has required low-sulfur diesel fuel for the last several years.


The company said its next step is to find a trucking company in Southern California that will test 25 to 30 trucks equipped with the smokeless engine.