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"Downsize" was the favored buzzword of the powertrain community at this year's Society of Automotive Engineers World Congress in Detroit.

Engine developers, suppliers and strategists spoke so repetitively about the need to reduce engine displacements in North America that "downsize" began to sound like the Congress' official Gregorian chant.

One of the most strident orchestrators was S.M. Shahed, president of Honeywell's Garrett Engine Boosting Systems (and 2002's SAE president). Shahed is alarmed about the powertrain competitiveness of U.S. auto makers and says there's only one near-term answer: downsized engines.

These smaller-displacement engines will be enhanced by, not coincidentally, advanced new turbochargers that can make the cubic-inch-cutting transparent to the nation's power-hungry automotive customers, Shahed contends.

"It's not displacement that counts. It's air that counts," he says, asserting the route to more-powerful engines comes not from larger size but from effectively moving air through the engine. Downsizing, combined with turbocharging to make up the inevitable performance deficit, can amount to a 20% fuel economy gain, he says.

"A 2L (4-cyl.) can take on a 3L (V-6)," Shahed insists, because a downsized turbocharged engine presents higher peak torque, at lower rpm, than a larger normally aspirated engine. Higher torque at lower rpm is what satisfies U.S. drivers, he says.

Shahed says Europe's breakneck adoption of diesel engines is the perfect illustration of his point. Today's high-performance diesels deliver usable torque with markedly less displacement than a gasoline engine needs to produce similar torque.

Diesels, he says, require about 20,000 gallons (88,000L) of air for every gallon of fuel; gasoline engines suck in about 9,000 gallons (39,600L) for every gallon of gasoline burned. So the better an engine breathes, the more torque it produces.

Chris Middlemass, Garrett's director of gasoline boosting systems, says although the U.S. market has yet to mimic Europe's affinity for light-duty diesels, the downsizing/turbocharging idea is equally relevant.

# posted by Medical Information : 4:13 AM