Cylinder deactivation

Automotive Industries, Jan, 2005 by John Peter

The idea of deactivating cylinders to reduce fuel consumption is nothing new. The technology, experimented with during WWII, made its North American debut in 1981 as a standard feature on all Cadillac models except Seville. Eaton Corp. developed the innovative V-8-6-4 system which used the industry's first ECU to switch the engine from 8-to-6 to-4 cylinder operation depending on the amount of power needed. Sadly, GM's V-8-6-4 was way ahead of its time and a rash of unpredictable failures relegated it to the scrap heap.

Today, thanks to advancements in electronic technology, cylinder deactivation is making a comeback. Mercedes developed a system that was made optional on European-spec V-8s in 1998, debuting on the 1999 S-Class. GM, along with Eaton and Delphi, have developed Displacement on Demand (DoD) for the Vortec 5300 V-8 that is an option on the 2005 Chevrolet TrailBlazer EXT, GMC Envoy XL and Envoy XUV. DoD switches from 8-cylinder to 4-cylinder mode enabling fuel economy gains of about 6 to 8 percent.

A new Vortec 3900 3.9L V-6, that will be optional on the new Pontiac G6 will also use a version of GM DoD.

Chrysler designed the new 5.7L Hemi with a similar Multiple Displacement System. The engine, an option on the Chrysler 300C, Dodge Magnum and Jeep Grand Cherokee, promises up to a 10 percent increase in fuel economy.

Honda's Variable Cylinder Management (VCM) system, introduced in 2003 on the J30A 3.0L V-6 in the Japanese Inspire made its North American debut on the 2005 Honda Odyssey minivan and Accord hybrid in the fall of 2004.