Cylinder Deactivation: A Good Thing?

Cruising down the highway your car is traveling at a set speed not needing the full use of all of its engine power, but eating up precious fuel nevertheless. That V6 or V8 under the hood could be much more efficient if it employed one important piece of modern day technology: cylinder deactivation. Does your vehicle have this feature? If so, exactly what does it do and is it a good thing? Read on to learn what some automakers are doing to conserve fuel without making significant changes to your vehicle.

Elevated fuel prices have consumers scrambling for answers. Some are switching to hybrids, others to diesel, while still others are choosing smaller and lighter vehicles all in a bid to save on fuel. While no one quite knows what the long term fuel prices will be, automotive manufacturers are able to squeeze out better fuel mileage through a rather simple technological change: cylinder deactivation. Cylinder deactivation works this way: let’s say you are cruising down the interstate at a set speed of about 65 miles per hour. The road surface is flat therefore there isn’t a whole lot of demand on your engine. Instead of running all six or eight cylinders, why not run your engine on three or four?

Back during the early 1980s, GM unsuccessfully tried this with Cadillac by offering what they called 8-6-4 displacement. Unfortunately, the technology wasn’t as refined as it is today and the experiment failed miserably. Today, however, thanks to central processing unit chips, displacement on demand is a viable alternative. When driving at cruise, sensors tell the engine to shut down half of its cylinders thereby reducing gas consumption. Although typical gains range in the neighborhood of just 5-7%, an across the board introduction of this technology could reduce our dependency on foreign oil and lift corporate fuel economy across the board.

For three years now GM has offered active fuel management [or AFM] with several V8 engines and the technology will soon find its way on V6 engines for the Chevy Uplander and Impala. Honda has its own variable cylinder management [or VCM] for select V6 powered Odysseys, Accords, and Pilots. Other automakers are studying the cylinder deactivation with more manufacturers expected to jump in.

Unlike previous attempts at engine deactivation, the latest attempt at shutting down unneeded cylinders appears to be a success. Thanks to refinement of the hydraulic valve lifters and improvements in engine and exhaust tuning, engines featuring cylinder deactivation technology are able to transition quickly and quietly from a fuel efficient mode to one requiring full power. Thus, consumers get the best of both worlds: power and maximum fuel efficiency.

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