The main fuel requirement for the cylinder is injected directly into the cylinder by a main jet (32). Additional jets (34,36,38) are fed with a secondary fuel feed. The secondary fuel feed is heated and pressurised to produce fuel vapour injected into the cylinder. The pressure and temperature are such that on meeting oxygen the fuel vapour ignites spontaneously and provides and ignites the main fuel feed. The fuel heating uses electrically heated rods in the fuel feed to heat the fuel up to 600 deg.C. The heating can be in stages, with the last stage on the cylinder side of the jets. Each fuel vapour jet produces a burn area in a preset position in area of the main fuel jet to produce an even burn.
