The ignitability, under low temperatures, of sunflower oil (or general plants oil) was much poorer than that of diesel oil. This might be due to the characteristics of sunflower oil itself and that the combustion chamber is pre-combustion chamber type. In this paper, being composed of the ignitability when sunflower oil burned in a pre-combustion chamber type diesel engine, was analysed, which has the most complicated structure among diesel engines.
As a result, the flow velocity at the connecting passageway became maximum at a crank angle of 20° before TDC. Its absolute value was 160m/s, which prevent the penetration of the particles into the main combustion chamber. This was the main cause of poor ignition in the pre-combustion chamber type diesel engine. When sunflower oil and No. 2 diesel oil were injected against this flow velocity, the initial velocity of No. 2 diesel oil was higher than sunflower oil because of the low density; however, the maximum penetration distance of sunflower oil was shout 1.6 times as large as No. 2 diesel oil because of the larger particle size.