- - Thursday, June 9, 2011

Anyone who has ever played the game “telephone” knows that the more times a message gets passed along, the less accurate it will be when it gets to its destination. The same thing applies to feeding fuel to an engine.

Across-the-board use of direct injection in the Buick lineup is helping to take translation layers out of the delivery process to reduce both fuel consumption and emissions. Buick is the only domestic brand powered exclusively by direct injected engines. Direct injection has enabled fuel economy improvements of up to 3 percent on the Buick Enclave, LaCrosse, Regal and the upcoming Verano - without sacrificing performance and still meeting the world’s most-stringent emissions requirements.

Over the past three decades, fuel delivery systems have evolved from the relatively primitive carburetor that relied on the Bernoulli effect to draw fuel through a tiny jet as air accelerated by, to the more-precise throttle body injection that gave way to port and finally direct injection. Today’s high-pressure direct injectors deliver fuel to the point of combustion in the cylinder so fuel doesn’t get left behind on manifold walls or evaporate up out of a carburetor. The demise of the carburetor ended problems like flooding and vapor lock and direct injection brings several benefits over the more recent sequential port fuel injection systems.

“The 2,200 pounds per square inch of pressure that feeds the injectors provides a more atomized and precisely metered fuel spray to each cylinder before every combustion event,” said Ecotec chief engineer Mike Anderson. When used on boosted engines like the 2.0-liter Ecotec Turbo in the Regal and the upcoming Regal GS, direct injection also provides a charge cooling effect. “Spraying fuel directly into the combustion chamber reduces the temperature of the compressed mixture as the fuel evaporates, which enables a higher-compression ratio, allows for more spark advance, and reduces fuel consumption” said Anderson. “The beefier low-end torque and improved drivability of the direct-injected 2.0L turbo makes it a no compromise high-efficiency substitute for a bigger and heavier V6.” Engines with direct injection also warm up faster thanks to the ability to add a second injection pulse right before the spark plug ignites the fuel following a cold start.

This faster warm up can cut emissions of unburned hydrocarbons by up to 25 percent. With direct injection, the 220 horsepower Regal Turbo beat the Acura TSX by 19 hp and 88 pound-feet of torque from just 2,000 rpm while still achieving up to 32 mpg on the highway, an advantage of 4 mpg. The Enclave is the most fuel efficient eight-passenger crossover on the market with an EPA estimated 17 mpg city and 24 mpg highway.



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