The feasibility of a direct-injection engine fuelled by liquefied butane has been explored for a single-cylinder four-cycle test engine having a high-swirled deep-bowl combustion chamber. A pressurized fuel has been injected from a multihole nozzle using a conventional diesel injection system. A ceramic glow plug has been installed at the combustion chamber to assist ignition of one of the sprays. Tests showing a smooth smoke-free running have evidenced the feasibility of this type engine. The reason for this smooth running has been clarified and is explained as follows: While the ignition-assisted spray ignites with a short delay, the remaining sprays have a long ignition delay owing to poor autoignitability. Thus a two-staged combustion takes place showing a lower rate of heat release in the earlier burning stage and a higher rate in the later stages. In addition, the effects of engine parameters on thermal efficiency, exhaust smoke, nitric oxides, and hydorocarbons have been studied in detail.