Boost With Brains

Automotive Industries, Sept, 2001 by John Peter

Garrett aims its new electrically-assisted "smart" turbocharger at light-vehicle diesels.

Dr. S. M. Shahed has a story to tell. And the Vice President of Advanced Technology for Garrett Boosting Systems is telling "The Diesel Story" to all who will listen.

Europe has embraced the direct-injection turbodiesel in an economy where fuel prices are high and the need for engines that produce less [CO.sub.2] is great (see related story, pg. 26). One in every three new cars sold in Europe is diesel powered, and 70 percent of premium and luxury cars feature clean diesel technology. This contrasts greatly with North America where only about 0.26 percent of all new cars sold are diesel powered, and the numbers are only slightly higher for light trucks.

As the leading supplier of passenger vehicle turbochargers (65 percent of the 11 million turbo units produced yearly go into cars and light trucks), Garrett believes that boosting the new clean diesels is the answer to both fuel consumption and environmental concerns.

"The modern diesel engine requires 20,000 gallons of air for every gallon of fuel used," says Shahed. "What we are working on is a smart way of supplying air, because a smart way of supplying the one gallon of fuel already exists."

Shahed says that "smart boosting" systems are the answer, offering a new frontier for performance, emissions and fuel economy. To this end, Garrett is currently developing an electrically assisted turbocharger (EAT). The Dynacharger is a fully integrated system utilizing a bi-directional power inverter and controller that is tied into the engine's ECU. Thus, boost is independent of the engine speed and can be controlled electronically. An electric motor spins the turbo until the engine pressure builds, eliminating any turbo lag. An added asset is that the turbo can also double as a generator.

"We can supply two to three kilowatts of power to speed the turbo up," says Shahed. "Under high speed conditions, the turbo can actually generate power. The ECU can slow the turbo to about 150,000 rpm because the engine doesn't need that much air, and the electric power can be used elsewhere in the car."

He adds that Garrett has tested the electric motor up to 150,000 rpm as a booster and 250,000 rpm as an electric generator.

The future, according to Garrett, is turbocharged. The company is forecasting 12 percent annual growth over the next five years worldwide, with Europe leading the boom. There, Garrett predicts half the cars will be diesel powered. There will also be a significant increase in turbocharged gasoline engines as well. BMW is working with Garrett on one. Another OEM is developing a gasoline turbo for a light truck. And Saab, a Garrett partner since 1977, recently announced it will be General Motors Corp.'s center of turbo expertise.

Of course, Garrett would love to see the turbodiesel market blossom in North America. But with sub-$2.00 per gallon gasoline prices, stringent exhaust emissions standards looming, the recent defeat of the SUV bill in the House of Representatives, and the increasing viability of hybrid and fuel cell technology, the turbodiesel still faces steep North American hurdles.

What can Garrett do to influence Americans to embrace turbocharged "clean diesel" power?

"Maybe," jokes Chen Yao, Garrett's director of marketing, "we need to lobby Congress for higher gas prices."