Gasoline engines engine efficiency

A higher compression ratio has made the modern gasoline engine more efficient than earlier ones, but has at the same time created a new problem. Under certain conditions the smooth explosion of the fuel-air mixture in the cylinder is replaced by knocking, which greatly reduces the power of the engine. 

Superior fuel economy (more thermally efficient) particularly at low speeds due to lack of restriction of the air flow air flow restriction occurs in a gasoline engine through the throttling action of the gas pedal. 

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-... 

At present the NSR concept is only applicable in markets where low-sulfur fuels (30 ppm S or less) are available, such as in Japan and Sweden. The first NSR catalyst was applied by Toyota in 1994 and currently (end of 2000) about 300.000 cars in Japan have been equipped with it. As the sulfur specifications of fuels is to be tightened, NSR technology will find wider application, as it allows gasoline-fueled engines to operate under conditions of increased fuel efficiency, implying that CO2 emissions will be lower. 

Within two decades of the introduction of tetraethyl lead, engine efficiency doubled, power per cylinder tripled, and the octane of regular gasoline rose from 55 to 75. Midgley s gasoline additive symbolized the technological wonders of industrial research and corporate America. Cheap... 

Fuel cells typically have higher efficiencies at lower power, so a hybrid fuel cell vehicle with battery will not improve its efficiency as it does for a gasoline engine. 

Natural gas (NG) consists of 85-95% methane (CH ), which is the simplest hydrocarbon. NG is the cleanest burning alternative fuel. Exhaust emissions from NG vehicles are much lower than those from gasoline-powered vehicles. Combustion of NG reduces carbon dioxide content compared with diesel, but the lost efficiency when the Otto process is used means that carbon dioxide emissions increase. All in all combustion of NG in a gasoline engine gives rise to about as much carbon dioxide as the combustion of diesel in a diesel engine, measured in units of energy. 

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