Cylinder deactivation
Automakers get about an 8% gain in fuel economy by shutting down half of the engine's cylinders. Here's how.
- The cylinders are turned off by keeping valves closed, keeping out air and fuel.
- In push rod engines, oil to the valve lifters is cut off on half the cylinders once the engine reaches cruising speed.
- On overhead-cam engines, valves are closed by locking and unlocking lobes on the camshaft.
Imagine being General Motors engineer Chris Meagher.