It depends on how much snow you are going to blow. The more money you spend the more power you will get. I just purchased this and only used it a few times. It is going back to Lowe's and I am purchasing a Honda single stage instead. This Troy Bilt is rated to handle about 6 inches of snow and that is not an understatement. The Honda which costs considerably more, will handle 12 inches of snow and are known for their quality. I own a Honda Civic and a Honda self propelled smart start mower-both excellent. While many have said they have had no issues starting this machine, it took me a dozen or more pulls to get it started. With my Honda mower, it always starts on the first pull. Would rather pay the extra and get quality.
Snowthower 123cc is 3.5 hp.
It depends on the engine. Horsepower is a measurement of the engines effect. CC the size... It is possible for engines with the same size to have different effects.
You cannot define horseower just by engine displacement. It needs much more information. - For instance , some of the 1970 and 80's F1 engines were developing over 1,000 HP -and they were only 3 litre engines - yet your average car with a 3 litre production engine is about 180 HP.