Es simplemente una inferencia que saqué de la definición de REV:
http://www.answers.com/topic/rev
To increase the speed of (a motor, for example): revved the engine.
To accelerate or increase: orders to rev up factory output.
To make livelier or more productive: revving ourselves up for the game; efforts to rev the economy.
v.intr.
To operate at an increased speed: heard the motors revving.
To accelerate in quantity or activity.