Pistons of the engine for JR diesel railcars often suffer damage caused by the fusion of piston head due to the high temperature of combustion flames. The authors have proposed an investigation method to measure the spectrum on diesel flames using optical fibers, and estimated the flame temperature from the data obtained by a simplified procedure. They applied this method to the practical engine to find solutions to the above mentioned problems. As a result, the process of the piston damage was made clear, and an adequate trouble-shooting measure was established.

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The demand for burning a low grade fuel on a medium speed diesel engine is increasing.
By introducing the electronics, the new engine developed can burn the low grade fuels on the whole range of load, from starting to full power.
The engine, without widely changing the basic constructions, has a variable timing system which controls fuel injection and intake valve timing by means of a microprocessor according to the engine conditions.
The test result shows that the newly developed engine is energy saving whith can efficiently burn the low grade fuels with improves startability and better performance under low load condition.

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The electronically controlled high pressure injection system (KOMPICS) for heavy duty diesel engines was developed at komatsu Ltd. in 1981. Although it was an innovation in the concept that both fuel quantity and injection timing were controlled electronically by solenoid valves, its complicated fuel lines needed improvements. The authors have developed the new hydraulically driven fuel injection system, KOMPICS-II, which has simplified fuel lines, still retains the abilities of high injection pressure and wide range of variable injection timing. This paper describes the experimental investigation of fuel pump characteristics of KOMPICS- II and its effect on the performance of diesel engines.

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