What's the deal with pulleys??

[ShagginJet]

Alright, so i seem to be lost. I was under the impression that a larger, light weight pulley would give the car a ittle more HP. Talked to a friend, and now I'm not sure.

Someone enlgithen me!!

Friend: The stock crank pulley is 5.2 inches in diameter, so for every rotation, it moves 16.3 inches of belt. (Get it? 16.3 inches is the circumference of the pulley, and since the belt wraps around the outside of the pulley, that's how much the belt gets moved.) The Unorthodox Racing pulley we installed is only 4.15 inches, so for the same revolution, only 13 inches of belt get yanked through. With the belt moving more slowly, all the accessories move more slowly, and less power is lost to the accessories.

Dan: that doesn't make sense

Friend: It explains how the smaller pulley moves the belt slower.