Search Results

This paper describes design enhancements and experimental tests performed on the Detroit Diesel 8V-71T Low Heat Rejection (LHR) Engine. The program objective was to increase brake power approximately 10% while maintaining or reducing brake specific cooling system burden and heat rejection to the engine compartment. In order to achieve these objectives, it was necessary to reduce average right bank exhaust temperatures approximately 23°C to insure acceptable engine durability at elevated power levels. All modifications simultaneously satisfy the rigorous constraints imposed by the U.S. Army's M109 Self Propelled Howitzer and M992 Field Artillery Ammunition Support Vehicle (FAASV). The M992 FAASV is a derivative of the M109 armored vehicle which utilizes the same chassis. Engine fuel supply system, exhaust manifold, turbocharger compressor, and fuel injector modifications were made in order to meet these requirements.

This paper was written to document the results of a development program conducted by Detroit Diesel Corporation in cooperation with U.S. Army. The purpose of this program, was to apply “state-of-the-art” low heat rejection (LHR) technology and cold starting improvements to the 8V-71T engine used in the Self-Propelled Howitzer and Ammunition support vehicles. The principal focus of this report covers the diesel engine air system, Low Heat Rejection cylinder head developments, and the resultant synergism impacting reduced cooling system burden, improved engine performance, reliability, durability, fuel economy, and smoke signature. Concurrent development of a glow plug system is integrated to this development with dramatic resultant impact on engine startability and tactical vehicle performance.

Air-to-air and air-to-water charge air cooling techniques significantly reduce charge air temperature; improving fuel economy and reducing NOx emission levels and cylinder temperatures of turbocharged two-stroke diesel engines. System selection is influenced by installation constraints, type of application, and cost considerations. Two new methods of charge air cooling as applied to on-highway diesel engines are described. The effects of environmental conditions and load factor on engine coolant and charge air temperature are analyzed.