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The effect of fuel properties on the performance of a new type of diesel engine with fuel jet impingement was investigated in comparison with the performance of a DI diesel engine. The new engine has a unique mixture formation process, but the details have not been well investigated. Therefore, the combustion processes of the engine was observed with a transparent piston engine and a high-speed camera system. Observations of the combustion process showed that after impingement, the fuel diffused almost symmeterically into the shape of a disk. Ignition usually started near the cavity wall and extented toward the center of the combustion chamber. The flame appeared to extend from the inside cavity radius to the outside cavity radius because of the strong squish flow. The fuel consisted of petroleum derived samples with a wide range of cetane number and viscosity. High cetane number resulted in reduced NOx mass emission from both engines, but an increased amount of smoke was emitted.

Performance and the compatibility of methyl tertiary butyl ether (MTBE) as a blending component for motor gasolines were assessed for Japanese passenger cars. MTBE was found to be an excellent road octane booster. But fuel consumption and exhaust emissions of MTBE-containing gasoline were observed to differ from conventional gasoline. The addition of MTBE changed the equivalence ratio of the mixture and reduced the calorific value of the fuel. Engine cleanliness, ORI and crankcase oil deterioration were not influenced by MTBE gasoline. MTBE gasoline was compatible with the elastomers and metals used for fuel system of Japanese passenger cars and was found to behave similarly to conventional gasoline. From these results, MTBE was judged to be an excellent octane appreciator in motor fuel for Japanese passenger cars.