Technical Paper
The Flexible Diesel Engine
1990-02-01
900175
Some advantages may be gained from permitting variation in diesel engines of parameters that are normally fixed, such as mechanical compression ratio. Such an engine could be described as a flexible engine. This paper describes the results of computer modeling work carried out on a hypothetical engine that could be in production by the year 2000 for heavy-duty truck application. The engine--a six-cylinder, in-line, turbocharged, four-stroke engine with air-to-air aftercooling-was modeled using the TRANSENG computer program. It had a swept volume of 8.5 liters and produced 224 kW (300 hp) at 2000 rpm. Modeling work was carried out with a variable geometry compressor, a low-speed optimized compressor, variable compression ratio, and variable valve timing using the Miller cycle. The variable geometry compressor allowed an increase in BMEP of 5 percent and a decrease in fuel consumption of the same amount at rated power.