Compression Temperatures in a Cold Cranking Engine

The UPS292sc, a late injection DISC (direct-injection stratified-charge) engine, has demonstrated extraordinary multifuel and cold starting capabilities. In this paper in-cylinder measurements of gas temperatures and pressures during & cold start are reported. Analysis of the results clearly indicates that the traditional description of the ignition process does not adequately explain cold starting in a late injection DISC engine. Alcohol droplets directed onto an operating spark plug at -20 °C were observed to ignite. It is believed that ignition proceeds via energy transmission from the alternating current spark, independent of the compressive heating. Ignition is therefore virtually independent of ambient temperature or fuel volatility.