GM to Offer Cylinder Deactivation on Some 2005 SUV Models

GM has revealed that the 2005 GMC Envoy XL, Envoy XUV and Chevrolet TrailBlazer EXT SUVs will be the first vehicles to offer the company’s new “displacement on demand” technology. The statement, reported by the SEMA E-news service, states that the system will reduce fuel consumption 8 percentabout 1.5 mpg for the SUVsby shutting off half the engine’s cylinders during light power requirements.
The technology will be standard in the 2005 SUVs’ optional Vortec 5300 V8 engine. About 100,000 vehicles with the powerplant are expected to be sold in 2005. The engines will use all cylinders during startup and when a vehicle is towing. At cruising speed, the engine control module closes half the intake and exhaust valves to conserve fuel. Valves are reopened as needed for acceleration. A vehicle must be in at least third gear for the system to function. In addition to special software algorithms, engines with the system will be outfitted with a small valve spring, lifter oil manifold assembly and a telescoping mechanism to open and close the valves. GM says the cost of the components is nominal.<br>
The 8-percent gain in efficiency is based on U.S. Environmental Protection Agency tests. GM predicts some motorists may experience more than a 20-percent improvement, depending on driving cycles.<br>
Ford Motor Co. and DaimlerChrysler AG are said to be developing similar technologies. DaimlerChrysler previously indicated it would add cylinder deactivation to its new 4.7-liter Hemi V8 in coming years.<br>
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