Aftertreatment requires one or more catalysts, and current catalysts are poisoned by sulfur and
phosphorus, both of which are present in, and critical to the performance of, current lubricants at
levels that are too high to allow practical catalyst life. Incidentally, the use of catalysts also may
require very low limits on the sulfur content of fuels.
In spite of the heavy emphasis on emissions, better fuel economy is not being ignored, especially
in view of the fuel penalty associated with the emission technologies. The highest potential for
fuel savings in the engine is the cylinder kit (piston rings and liners), but the potential from
overhead components (cam rollers and rocker-arm bushings) and main bearings is not
insignificant. Just from the cylinder kit and bearings, the potential fuel savings are estimated to
be about 5 gallons per vehicle per day. In 1996, there were approximately 1.7 million Class 8
trucks on the road. Reducing fuel consumption for that fleet by 5 gallons per day would result in
an annual reduction of 0.4 quads, or 69 million barrels of oil equivalent.
Extended durability could be achieved with better (less-empirical) design methods for
hydrodynamic lubrication conditions and advanced bearing concepts for mixed lubrication
A significant barrier to increasing power output is the temperature capability of in-cylinder
components. Improved materials, coating, and surface treatments are needed, along with
improvements in combustion and cooling technologies.
Solving the engine-related problems will require an integrated engine/system approach,
including development of
Novel experimental methods.
New designs, materials, and coatings.
Innovative lubricant formulations and concepts.
Novel experimental methods should include
Development of accelerated bench tests that correlate well with long-term, full-scale
Development of sensors to monitor engine performance and lubricant condition.
Basic investigations into the fundamental nature of friction and wear.
Development of sophisticated characterization techniques.
Those developments would be appropriate for national laboratories and universities, which
would coordinate with the engine manufacturers, who would identify needs, down-select
technical approaches, and conduct fixture and engine tests.
The mathematical bases for new predictive models probably should be developed at national
laboratories or universities, with engine consulting companies developing the commercial codes.
The engine manufacturers would identify needs, provide phenomenological descriptions and data
for validation, and apply the results to new designs.