My 455 is 22HP engine rated, and handles the Deere 450 tiller at 50" wide VERY well. Power is not an issue, but holding it back in soddy earth definitely is. This tiller has a lot of push, and has dug ouy many a rock, some the size of bowling balls. The only time I've had the engine really work is if I really try to run fast on the hydro pedal or get stuck. The reality is, if I go fast enough to labor the engine, the tiller doen't go as deep anyhow so the hydro is really what works the engine.