You may be looking at units which differ in the configuration.....some may be two-cylinder TWO STAGE and some may be two-cylinder ONE stage. Also, I've never seen a Campbell Hausfield in a machine shop, a truck shop, or a body shop slugging away hour after hour, whereas I've seen a lot of Quincys and IRs. That might be a clue. I was looking at some units recently and I found that it was difficult to compare HP ratings without using the running amps of the motors since the motor nameplates are phonied up to deliberately confuse the buyers. Compare amps motor to motor and you'll get a better idea. [img]/forums/images/icons/tongue.gif[/img]