General Motors, Eaton Make Full-Size SUVs More Fuel Efficient with Cylinder Deactivation

SOUTHFIELD, Mich.--Oct. 6, 2005--General Motors recently unveiled its new line of 2007 model year full-size sport utility vehicles equipped with Displacement on Demand, an innovative valve train technology developed by GM and Eaton Corporation to improve the fuel economy of the V8-powered vehicles.

Displacement on demand is a fuel-saving technology that enables the engine to seamlessly operate on only half of the engine's cylinders when full power is not needed, improving efficiency by as much as 12 percent in some vehicles. GM reports that with Displacement on Demand the full-size 2WD 2007 Chevrolet Tahoe gets 20.5 mpg (EPA unadjusted combined mpg.)

"We have been able to leverage our expertise in valve train technology and hydraulic solenoid technology to create an unique system for customers that actually changes the engine's displacement based on the performance required," said Jeffrey Romig, vice president and general manager, Eaton Valve Actuation. "The system can switch to a four-cylinder operation without any discernible change in performance and without the driver even noticing. This can result in significant fuel savings."

The system functions through the interaction of two key elements: An "intelligent" valve lifter, and an industry first from Eaton, the lifter oil manifold assembly (LOMA). Based on driving conditions such as vehicle load and speed, the vehicle's engine controller determines if conditions are appropriate to switch from eight cylinders to four cylinders. If a vehicle has a light load, for instance, or is cruising at highway speeds, the system shuts down the cylinders until more power is needed.

When the driver accelerates or needs more towing capacity the system seamlessly re-engages all the cylinders. "The process happens instantaneously and is undetectable by the driver. The system can shift on and off as often as necessary, often several times a minute," Romig said.

The "intelligent" valve lifter is the technology that uncouples the unneeded intake and exhaust valves, while the lifter oil manifold assembly - neatly tucked in an open space in the engine cavity - is responsible for directing engine oil pressure to and from the lifter during cylinder deactivation and reactivation.

GM introduced Displacement on Demand in the 2005 Chevy TrailBlazer EXT and GMC Envoy XL mid-size SUVs. For the 2006 model year, GM offers the fuel-saving technology on nine different models, including the new Chevrolet Impala SS and Monte Carlo SS.

Eaton Corporation is a diversified industrial manufacturer with 2004 sales of $9.8 billion. Eaton is a global leader in electrical systems and components for power quality, distribution and control; fluid power systems and services for industrial, mobile and aircraft equipment; intelligent truck drivetrain systems for safety and fuel economy; and automotive engine air management systems, powertrain solutions and specialty controls for performance, fuel economy and safety. Eaton has 57,000 employees and sells products to customers in more than 125 countries. For more information, visit www.eaton.com