GM's next V-8s will feature cylinder deactivation
DETROIT -- General Motors will use cylinder deactivation on its next generation of trucks, part of a menu of tricks to deliver competitive fuel economy without sacrificing V-8 power.
Last week, GM engineers confirmed that the company's fifth-generation small-block V-8 engine slated for service in GM's redesigned pickups and SUVs will include cylinder deactivation, which GM calls "active fuel management." GM has been using the technology on its full-sized pickups since 2007.
GM engineers say active fuel management increases fuel efficiency by up to 8 percent and is the single most potent gasoline-engine technology it can deploy to boost mpg. The re-engineering of its pickups and SUVs has allowed GM to optimize the system and potentially wring out more fuel savings.
The system shuts off the combustion in four of the eight cylinders under low-revving conditions, such as decelerating or coasting on the highway. It saves gasoline by cutting off the fuel to those cylinders while shutting off the valves to stop unnecessary pumping. It also allows the remaining four cylinders to work more efficiently, GM says.
GM's redoubled commitment to cylinder deactivation is another example of the diverging pickup strategies of GM and Ford Motor Co.
GM will use that and other technologies -- such as lighter materials and eight-speed transmissions -- to lift fuel efficiency on the next-generation Chevrolet Silverado and GMC Sierra, due by next summer. But GM is putting more emphasis on power and ruggedness while relying on redesigned mid-sized pickups -- the Chevy Colorado and GMC Canyon -- to woo more fuel-conscious buyers.
GM's full-sized pickup customers demand "performance and durability and driveability and fuel economy," says Mark Stabinksy, a lead engineer for GM's active fuel management system. "There are other options" to boost fuel efficiency, he says. But active fuel management is "the perfect choice."
Meanwhile, Ford, which does not offer cylinder deactivation, is making a more explicit fuel economy play. It wants to build on the success of its turbocharged EcoBoost V-6 engine in the F-150 pickup.
A spokesman says Ford's strategy of turbocharging while reducing engine size -- often substituting V-6s for V-8s -- "yields better results" than cylinder deactivation.
Chrysler Group, which first introduced cylinder deactivation on the 2005 Chrysler 300C, uses the technology on the Ram pickups with V-8 Hemi engines. GM's first use of active fuel management was on the 2005 Chevy TrailBlazer.
Today, GM offers the system on most of its V-8 engines, including those in all of its light-duty pickups and SUVs and some Camaro models. This year, vehicles with cylinder deactivation are expected to account for 28 percent of overall sales, GM says.
Jordan Lee, global chief engineer for small block engines, says GM will consider an array of technologies to enhance fuel efficiency on the next-generation trucks, including turbocharging, supercharging, electrification and diesel. But, he says, "We want to go after fuel economy in a way that really meets the needs of our customers."
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