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High-temperature lubricant (HTL) requirements for future U.S. Army ground vehicles were investigated. A single-cylinder diesel engine (SCE-903) was successfully modified to operate at increased cylinder liner temperatures and to serve as a tool for HTL evaluation. Oil D, one of six lubricants evaluated, completed 200 test hours at an average cylinder wall temperature of 247°C and an oil sump temperature of 166°C with only minor oil degradation. However, improved piston cleanliness is desired.

Combustion studies on various potential alternative fuels were performed for the U.S. Array Belvoir Research and Development Center in a two-stroke heavy duty diesel engine. One cylinder of the engine was instrumented with a pressure transducer. A high-speed data acquisition system was used to acquire cylinder pressure histories synchronously with crankangle. The heat release diagrams, along with the calculated combustion efficiencies of the fuels were compared to a referee grade diesel fuel. The calculated and measured combustion parameters include heat release centroids, cumulative heat release, peak pressure, indicated horsepower, peak rate of pressure rise, indicated thermal efficiency, energy input, and ignition delay. Regression analyses were performed between various fuel properties and the calculated and measured combustion performance parameters. The fuel properties included specific gravity, cetane number, viscosity, boiling point distribution.

Several test programs have shown that the combustion of methanol in spark ignition engines can cause unusually high corrosive wear of the upper cylinder bore and ring areas. In this study, a 2.3-liter engine fueled with methanol was operated in a nitrogen-free atmosphere to determine the importance of nitric acid in the corrosion mechanism. A 20-hour steady-state test was carried out using neat methanol as the fuel and a mixture of oxygen, argon, and carbon dioxide in place of air. Only trace amounts of NOx and nitric acid were found in the exhaust products during this test. The wear, indicated by iron buildup in the lubricant, was found to be essentially the same in the nitrogen-free test as that detected in baseline engine tests combusting methanol-air mixtures. It was concluded that nitric acid does not play a role in the corrosion mechanism.