Higher mechanical and tribological stresses and higher temperatures of advanced designs limit the engine designer advanced materials allow the design of components that may operate reliably at higher stresses and temperatures, thus enabling more efficient engine designs. The design of advanced components for high-efficiency diesel engines has, in some cases, pushed the performance envelope for materials of construction past the point of reliable operation. Once an engine is made certifiable, subsequent challenges will be in cost noise, vibration, and harshness (NVH) and performance. The foremost barrier to diesel use in this market is emission control. Application of the diesel engine to class 1,2, and 3 trucks is expected to yield a 35% increase in fuel economy per vehicle.

OIT OHVT also recognizes a significant opportunity for reduction more » in petroleum consumption by dieselization of pickup trucks, vans, and sport utility vehicles. Heavy Vehicle Propulsion System Materials will, in concert with the heavy duty diesel engine companies, develop the durable materials required to commercialize the LE-55 technologies. However, the commercialization of the LE-55 technology requires more durable materials than those that have been used to demonstrate the goals. The LE-55 program is being completed in FY 1997 and, after approximately 10 years of effort, has largely met the program goals of 55% efficiency and low emissions. The goal is also for the LE-55 engine to run on natural gas with efficiency approaching that of diesel fuel. The Office of Transportation Technologies, Office of Heavy Vehicle Technologies (OIT OHVT) has an active program to develop the technology for advanced LE-55 diesel engines with 55% efficiency and low emissions levels of 2.0 g/bhp-h NOX and 0.05 g/bhp-h particulate. The purpose of the Heavy Vehicle Propulsion System Materials Program is the development of materials: ceramics, intermetallics, metal alloys, and metal and ceramic coatings, to support the dieselization of class 1-3 trucks to realize a 35% fuel-economy improvement over current gasoline-fueled trucks and to support commercialization of fuel-flexible LE-55 low-emissions, high-efficiency diesel engines for class 7-8 trucks.

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