General Motors and Delphi Make Vehicles More Fuel Efficient with Displacement on Demand

TROY, Mich., April 4 -- As part of a powertrain technology strategy to develop solutions to conserve gasoline and improve fuel economy, General Motors launched the Vortec 5300 V-8-powered 2005 Chevy TrailBlazer EXT and GMC Envoy XL with new Delphi-produced valve train technology. Developed by Delphi Corp. , in conjunction with General Motors, Displacement on Demand cylinder deactivation technology improves the fuel economy of these SUVs by up to 8 percent based on the federal testing procedure.

As the subject of fuel economy heats up this summer, technologies to help extend the distance a vehicle will travel on a tank of gas should become top- of-mind for automakers and consumers. GM has already indicated that it expects to equip as many as two million vehicles with Displacement on Demand by 2008.

"Displacement on Demand provides an immediate cost-effective solution to the growing concern of fuel consumption worldwide," said Jean Botti, business line executive for Delphi's powertrain systems. "Today, Delphi develops valve train systems and components by focusing on optimizing the overall efficiency of the engine. By leveraging our comprehensive understanding of the engine management system, we can work with the customer to define exact needs from an engine output perspective."

Displacement on Demand is an advanced valve train technology that seamlessly "turns off" half of the engine's cylinders under certain driving conditions. For example, with an eight-cylinder gasoline engine, four of the cylinders cease to operate when there is a light load on the engine. The engine continues to be even firing on the remaining cylinders. The system precisely closes the intake and exhaust valves on targeted cylinders using electronically-controlled hydraulic actuation while disabling fuel and spark to those cylinders. Fuel economy is improved because the firing cylinders operate at higher load, reducing the pumping losses of the overall engine.

Additional Benefits

In addition to fuel savings, the customer-specific design of Displacement on Demand provides optimized functionality and calibration flexibility. The system provides reliable, seamless switching between modes within one engine cycle that is undetectable by the driver. Low reciprocating mass in deactivated mode minimizes lost motion spring load and associated friction. The "drop-in" design of the deactivation lifter for most pushrod applications allows for ease of assembly, reducing time and cost for the vehicle manufacturer.

A combination of Displacement on Demand with other fuel saving technologies such as Electric Power Steering or cam phasing would provide additional benefits to vehicle manufactures and consumers alike.

"Displacement on Demand is being added to high-volume vehicles with notable opportunities for improved fuel economy," said Guy Hachey, vice president Delphi Corp. and president of Delphi Energy & Chassis. "The amount of fuel saved in the next few years likely will be significant. While higher- cost hybrids and fuel cells may provide long term solutions, Displacement on Demand is ready today."

Delphi's cylinder deactivation technology is manufactured in Grand Rapids, Michigan.