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The improvement of fuel consumption is the most important issue for engine manufactures from the viewpoint of energy and environment conservation. A piston-cylinder system plays an important role for the reduction of an engine friction. For the improvement of the frictional behavior of the piston-cylinder system, it is beneficial to observe and analyze the frictional waveforms during an engine operation. To meet the above-mentioned demand, frictional waveforms were measured with using the renewed floating liner device. In the newly developed floating liner device, an actual cylinder block itself was used as a test specimen. The measured single cylinder was an aluminum monolithic type made of hypereutectic Al-17%Si alloy using a high pressure die casting process. The combined piston was a light weight forged piston and a DLC coated piston ring was used. For the measurement, 110cc air cooled single cylinder engine was used.

Global warming caused by greenhouse gases are currently a significant problem in the world. Hydrogen is regarded as one of the possible sources of energy for the future. Hydrogen fueled engines emit no carbon dioxide as tank-to-wheel. Hydrogen engines can reduce greenhouse gases in comparison to engines fueled with fossil fuels. A pre-mixed hydrogen-fueled engine, specifically, can be put into practical use in a short period of time from a technical point of view. However, there are some technical issues, such as backfiring and low power output to resolve. With the aim to put a pre-mixed hydrogen-fueled engine for trucks and buses into practical use, it is necessary to prevent backfiring and to develop a high output engine. A diesel engine modified as a pre-mixed hydrogen-fueled engine was equipped with a variable geometry turbo-charger for higher output.