The Pumping Loss
A so-called "pumping loss" is also cited as causing extra work for the engine to do under partial load conditions because the pistons have to work harder to suck in the fuel-air mixture when the throttle position results in low intake-manifold pressure. Under this scenario, deactivating some of the cylinders allows the remaining active ones to have less manifold vacuum to overcome during the intake stroke.
Read more about this topic: Active Fuel Management
Famous quotes containing the words pumping and/or loss:
“It is by teaching that we teach ourselves, by relating that we observe, by affirming that we examine, by showing that we look, by writing that we think, by pumping that we draw water into the well.”
—Henri-Frédéric Amiel (1821–1881)
“Claudio. The old ornament of his cheek hath already stuffed tennis-balls.
Leonato. Indeed, he looks younger than he did, by the loss of a beard.”
—William Shakespeare (1564–1616)