Niagara Gazette — Two designs available
The technology is available for 4, 6, 8 or 12 cylinder engines. Systems can deactivate up to ½ of engines’ cylinders.
1. Pushrod engines: in pushrod engines cylinder deactivation is achieved by bleeding off oil pressure to the lifters of the valves in the cylinder/s to be cancelled. This stops mechanical manipulation of the valves, leaving them closed.
2. Overhead cam engines: on engines where the valves are opened and closed by overhead camshafts, engine designers use a split rocker arm for each valve. One rocker arm rides on cam lobes and mechanically manipulates nothing, while the other rocker opens & closes the valve. When the cylinder is to be cancelled, oil control to a pin locking the two rockers together releases the pin causing the valve-actuating rocker to sit without being moved, thus closing the valves. The other rocker simply rides on the cam lobe manipulating nothing.
Benefits of cylinder deactivation
Engines using the technology offer greater fuel efficiency. Carmakers claim an average of up to 20% fuel economy. The EPA did a study on this and came up with 7.5% savings overall.
Cadillac’s attempt at cylinder deactivation in 1981
When OPEC flexed their collective muscle on North America on the late 70s thru early 80s limiting oil production, GM, in an effort to lead the field in fuel economy decided to introduce a new engine management system called the “Cadillac 8-6-4. This system was touted by Cadillac to deliver 20% or more fuel savings.
The problem with Cadillac’s 8-6-4 cylinder deactivation system
When Cadillac tried cylinder deactivation in 1981, the concept was very unreliable because computer systems were primitive and unable to manage engine controls necessary to attain seamless operation. Today’s sophisticated computer systems powerfully and seamlessly control all elements of cylinder deactivation.
Cylinder deactivation systems available today
What companies offer the technology? What are their unique “brand names” for it? See below: