Hcci, General Motors Clean and Efficient Engine in One

By: Evander Klum

A dark blue Saturn Aura is turning around the ovals of General Motors. It may look like any fresh model set for drive testing, but under the hood of this vehicle is an experimental engine that General Motors believe is the next milestone for fuel economy and emission control. Together with this Aura, GM is introducing the world the homogeneous-charge compression ignition engine (HCCI). Aside from other electrical connectors, this engine sets the Saturn Aura from other engineering prototypes.

According to GM's researchers, the HCCI engine runs on a combustion process that holds the potential for advancements in fuel efficiency. Although several auto companies are developing the same system, GM is one of the pioneers.

The HCCI engine has the finest engine qualities, diesel engines that offer low fuel consumption and technology controlled low emissions.

As of now, further refinements will be needed for the engine. When it will be ready for the road, is the question that GM cannot answer at the moment. GM's engineers and computers will maintain the engine on its operating range. According to experts, the works will be worth the investment.

In a New York Times interview with Chris Gerdes, associate professor of mechanical engineering at Stanford University, he was quoted saying "I believe H.C.C.I. represents the next great advance of the internal combustion engine," The renowned
University is part of the HCCI research with GM.

"With minimal changes to the engine hardware, H.C.C.I. gasoline engines should be able to produce diesel-like efficiencies while simultaneously lowering emissions," he further stated on the same interview.

The engine has the potential to raise fuel efficiency by 15 percent to 20 percent and at the same time, it will cause oxides of nitrogen reductions said Dennis Assanis, director of the Walter E. Lay Automotive Laboratory at the University of Michigan.

The 2.2 liter engine used in the Aura test was basically based from the GM Ecotec 2.4 liter four cylinder engine available in the Aura next year. A power of 180 horsepower and 170 pound-feet of torque is expected to be generated from the HCCI engine. On the other hand, the engine of the 2008 Aura will be generating a lesser power of 164 horsepower and 159 pound-feet.

The HCCI engine works by igniting an equal distribution mixture of fuel, air and exhaust gas. Like how diesel engine works, combustion is spontaneous from the heat in the cylinder.

"H.C.C.I. relies on a very delicate balance of chemistry happening thousands of times per minute in the cylinder," said Paul Najt, a manager in G.M.'s powertrain research laboratory in his interview with the NYT.

"Controlling the chemistry is the difficult part to implement," he said. "If the temperature and gas composition aren't precisely correct, either nothing happens or something very bad happens." He added. Mr. Najt had been working on the HCCI project for more than 30 years.

Aside from GM (factory manufacturer of ), other international auto companies are on their works for engine development. Volkswagen is developing their Combined Combustion System; Mercedes-Benz will be publicizing the details of their Controlled Auto Ignition Sytem and Honda with their own HCCI which was originally for racing motorcycles and is now tested in a four-cylinder car engine.

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