Early/late Exhaust Valve Closing
Early and late exhaust valve closing can also reduce emissions. Traditionally, the exhaust valve opens, and exhaust gas is pushed out of the cylinder and into the exhaust manifold by the piston as it travels upward. By manipulating the timing of the exhaust valve, engineers can control how much exhaust gas is left in the cylinder. By holding the exhaust valve open slightly longer, the cylinder is more emptied and ready to be filled with a bigger air/fuel charge on the intake stroke. By closing the valve slightly early, more exhaust gas remains in the cylinder which increases fuel efficiency. This allows for more efficient operation under all conditions.
Read more about this topic: Continuous Variable Valve Timing
Famous quotes containing the words early, late, exhaust and/or closing:
“Perhaps the most valuable result of all education is the ability to make yourself do the thing you have to do, when it ought to be done, whether you like it or not; it is the first lesson that ought to be learned; and however early a man’s training begins, its probably the last lesson that he learns thoroughly.”
—Thomas Henry Huxley (1825–95)
“Lancaster bore him such a little town,
Such a great man. It doesn’t see him often
Of late years, though he keeps the old homestead
And sends the children down there with their mother
To run wild in the summer a little wild.”
—Robert Frost (1874–1963)
“Language is like soil. However rich, it is subject to erosion, and its fertility is constantly threatened by uses that exhaust its vitality. It needs constant re-invigoration if it is not to become arid and sterile.”
—Elizabeth Drew (1887–1965)
“And if the stage-dark head rehearse
The fifth act of the closing night,
Why, cut it off, piece after piece,
And throw the tough cortex away....”
—Allen Tate (1899–1979)