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Combustion and exhaust emission characteristics were compared among three representative diesel fuels called “Base (corresponding to a Japanese market fuel)”, “Improved” and Swedish “Class-1” using both a modern small and an optically accessible single-cylinder DI diesel engines. In these tests, the relative amount of PM collected in the exhaust was “Base” >“Class-1” >“Improved” at almost all of the operating conditions. This means that “Class-1” generated more PM than “Improved”, even though “Class-1” has significantly lower distillation temperatures, aromatic content, sulfur, and density compared with “Improved”. There was little difference in combustion characteristics such as heat release rate pattern, mixture formation and flame development processes between these two fuels. However, it was found that “Class-1” contained more branches in the paraffin fraction and more naphthenes.

According to the principle of pH measurement, an on-board type engine oil deterioration sensor has been developed. The developed sensor is composed of a Pb and oxidized stainless steel electrodes. The sensor signal shows a good linear relationship to the quasi-pH value of the oil. Especially in the region where the oil deterioration proceeds, the remaining basic additives in the oil is easily estimated from the sensor signal.

Fifty percent distillation temperature (T50) can be used as a warm-up driveability indicator for a hydrocarbon-type gasoline. MTBE-blended gasoline, however, provides poorer driveability than a hydrocarbon-type gasoline with the same T50. The purposes of this paper are to examine the reason for poor engine driveability caused by MTBE-blended gasolines, and to propose a new driveability indicator for gasolines including MTBE-blended gasolines. The static and dynamic evaporation characteristics of MTBE-blended gasolines such as the evaporation rate and the behavior of each component during evaporation were analyzed mainly by using Gas Chromatography/Mass Spectrometry. The results of the analysis show that the MTBE concentration in the vapor, evaporated at ambient temperature (e.g. 24°C), is higher than that in the original gasoline. Accordingly, the fuel vapor with enriched MTBE flows into the combustion chamber of an engine just after the throttle valve is opened.