A Study of Highly Turbocharged High-Speed Diesel Engines

Abstract

The paper discusses the potential of a conventional high-speed diesel engine for operation at increased power output (+ 50 per cent), using readily available components and ancillaries, whilst retaining the traditional virtues of good thermal efficiency, ruggedness and low cost. The baseline engine was turbocharged and intercooled having a maximum b.m.e.p. of 14 bar at 1500 r/min. The research engine was designed for, and operated at a b.m.e.p. of 21 bar at the same speed. The results of a computer simulation and extensive experimental programme using an 11 litre in-line six-cylinder engine are presented. The project demonstrates the contribution that computer modelling may make to the design of turbocharged engines, making possible a considerable reduction of the costly development phase. The effects of compression ratio, valve timing, fuel injection and turbocharger match on performance and mechanical and thermal hading are discussed. Although extended durability testing was beyond the scope of the project, piston, cylinder head and valve temperature measurements show that metal temperatures were within accepted limits. The thermal efficiency of the research unit was consistently within the range 37–38.5 per cent at the target power output, which compares well with the baseline engine.