Extended run wear and deposit assessment on a DDA 6v92TA diesel operating on low cetane fuel

This paper reports on the progress of an ongoing engine durability study to assess wear and deposit accumulation in a heavy duty high speed military pattern diesel operating over a 500 hour test period on a low ignition quality fuel. Three test runs have been completed, one test run with a commercial diesel reference fuel and two runs with test fuels representative of the mid 1990s in Canada. The two test fuels had cetane numbers of 32.8 and 34.5 and were of the same blend components as the Canadian 1990s and beyond experimental fuel used in previous engine performance/combustion studies. These fuels contained conventional and tar sands derived components blended with a catalytically cracked light cycle oil. The engines used in the study were from the Detroit Diesel Allison 6V92TA (turbocharged and aftercooled) two-stroke diesel family. The continuous 500 hour test cycle format was designed to be typical of military operation. During the engine operational periods, injection, combustion and emission characteristics were recorded. Following each 500 hour test run the engine was disassembled and critical components were assessed for wear and deposit accumulation. The lubricating oil (SAE 40 API SF/CD) wear metal content and deposit levels were higher for themore » two low ignition quality test fuels. Peak combustion pressures and rates of combustion pressure rise were also higher. The study conclusions indicate that lowering ignition quality (33-35) increases engine wear and deposit accumulations. The increases in deposit levels were not considered dramatic but the increases to piston ring wear (in particular to the fire ring) would appear to substantially reduce engine life.« less