Research by Mazda engineers on combustion in spark-ignition and HCCI petrol engines has been awarded the Outstanding Technical Paper award by the Society of Automotive Engineers of Japan (JSAE).

Homogeneous Charge Compression Ignition (HCCI) is a form of internal combustion in which fuel and air are well mixed and then compressed to the point of auto-ignition. Normally this would create uncontrolled combustion or knocking, but in HCCI the temperature and pressure conditions inside the cylinder are carefully managed so that the timing of ignition can controlled.

The paper analyses the effects of different fuel components on ignition performance in a high-compression gasoline engine which uses HCCI - homogeneous charge compression ignition.

The four researchers - from Mazda, Cosmo Oil and Waseda University - developed a theoretical model that can predict auto-ignition timing for the various grades of gasoline used in different markets. The paper also showed that, when the engine was operated with spark ignition, the extra heat generated as the piston approached top-dead-center did not increase the likelihood of knocking, enabling increased power output. The results of this analysis were used in development of Mazda's Skyactiv-G engine (above) which has a compression ratio of 14.0:1.