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This paper presents a study of antiknock performance under various octane numbers and compression ratios in a direct injection spark ignition (DISI) gasoline engine. The relationship between the octane number and engine performance in the DISI engine-the engine torque and the break specific fuel consumption (BSFC)-was investigated in comparison with a multipoint injection (MPI) engine. Due to the improvement in the charging efficiency and the advance of the ignition timing by cooled aspiration, the engine torque of the DISI engine was improved over that of the MPI engine. It was also found that the octane number requirement (ONR) was reduced. In addition, the possibility of engine performance enhancement at high compression ratios was studied. At high compression ratios, the engine torque is reduced due to the heavy knocking when low octane gasoline is used. However, an improvement in the engine torque has been observed with high octane gasoline.

Fuel cell vehicles (FCVs) are an emerging transportation technology, with a potential to provide very low vehicle emissions and significant improvements in fuel efficiency. The choice of a fuel for FCVs must consider several critical issues, including the availability of a distribution and storage infrastructure, manufacturing cost and capital requirements,energy efficiency, and performance. Gasoline, one of the candidate fuels, is noteworthy not only for its existing infrastructure, but because it has the possibility of usage for both FCVs and conventional internal combustion engines. Gasoline consists of different types of hydrocarbons, including paraffins, naphthens, olefins and aromatics - - with carbon numbers distributed over a wide range. Gasoline also contains a variety of sulfur compounds and selected additives in small amounts., In some cases gasoline also contains oxygenates such as MTBE and ethanol.