Diesels

Diesels - Diesel Futures Forget the black soot and smoke....

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Diesel Futures Forget the black soot and smoke. Modern diesel-powered cars are quiet, clean and fast. BY PAUL WEISSLER Photo by Thorsten Weigl You would expect the 6-cylinder engine in the Mercedes E-Class and the V8 in the BMW 7 Series to be so smooth and quiet from the driver's seat that you'd have to look at their tachometers to be sure that they were running. You would not expect that of a diesel, however. Yet these are diesel engines. The world has been looking to gas/electric hybrids and fuel cells for future fuel efficiency. However, studies show that the diesel can equal or beat what the fuel cell might possibly deliver, and be within a gnat's whisker of a gasoline hybrid like the Prius. The studies of total energy consumption--so-called well-to-wheel studies--were conducted by General Motors, the Massachusetts Institute of Technology (MIT) and the University of Alberta in Canada. The MIT researchers, looking ahead to 2020, found the diesel well ahead of most hydrogen fuel cell possibilities and even ahead of the gas/electric hybrid. To demonstrate the diesel's acceptability, the Chrysler Group and Mercedes-Benz plan to join the only current diesel passenger-car importer, Volkswagen, with new models of their own. As of now, only the VW Jetta/Golf/Beetle 1.9-liter 4-cylinder turbocharged direct injection (TDI) is sold in the States. VW also will bring a more advanced 2.0-liter for the Passat, and probably a 5.0 V10 that develops 308 hp and 550 ft.-lb. of torque for its new Touareg SUV. These new diesels will be sold next year in test quantities. That means just a few thousand each of the Jeep Liberty 2.8 Four and the Mercedes E-Class with a 3.2-liter inline Six. As we go to press, there has been no decision by Ford about its diesel Focus. BMW's 4.0-liter V8 is not coming here soon. A Primer A diesel has no spark plugs. It has a very high compression ratio--about twice that of a gasoline engine. So the compression stroke builds up tremendous heat and pressure. A readily combustible fuel is injected and the heat of compression instantly ignites it. Unlike a gasoline engine with a throttle plate to regulate airflow, the diesel is unthrottled. It draws in all the air it can, all the time, without wasting energy pulling air past a partly closed throttle. Performance is determined (within combustion limits) by the
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This note was uploaded on 07/22/2008 for the course AME 436 taught by Professor Ronney during the Spring '08 term at USC.

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Diesels - Diesel Futures Forget the black soot and smoke....

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