Gasoline engines compression ratio

The technology employed by the car manufacturers in these countries to meet such stringent controls is based upon the use of oxidation or 3-way noble metal catalysts. Associated with this is the requirement to use unleaded gasoline that has in turn necessitated reversion to engine compression ratios of pre 1970 values with their associated increased fuel usage. 

Eor a considerable period, >90% of the new cars in Brazil operated on E96 fuel, or a mixture of 96% ethanol and 4% water (82). The engines have high compression ratios (ca 12 1) to utilize the high knock resistance of ethanol and deUver optimum fuel economy. In 1989 more than one-third of Brazil s 10 million automobiles operated on 96% ethanol/4% water fuel. The remainder ran on gasoline blends containing up to 20% ethanol (5). 

The diesel engine operates with a much higher compression ratio (CR) than does a gasoline engine, and therefore is manufactured with structurally... 

The best efficiency attainable from a gasoline engine of specified power rating depends heavily on four parameters compression ratio, air/fuel ratio, spark timing, and the fraction of the mechanical energy developed in the cylinder or cylinders devot-... 

The thermodynamic cycle for hydrogen is much closer to the ideal Otto cycle than for either a gasoline or a diesel engine. In addition, the compression ratio can be higher. 

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