180cc is the engine displacement in cubic centimeters, this is equivalent to about 11 cubic inches. How much horsepower this engine can develop depends on its design, some motorcycle engines get 1 hp per 10 cc, so this engine could get 18 horsepower or even 20.
Anywhere from about 1 horsepower up depending on how efficient the engine design is. There is no formula that says this capacity will give that amount of power, it’s a question of getting the engine and testing it on a dynamometer.
180cc is 5,5 hp
4.5 to 5.0 hp