Since there are 15 to 17cc to every 1 horsepower, a 49cc engine typically has about 3 horsepower. However, this conversion may be offset by certain features, like supercharging and exhaust turbo boosting.
Though each unit refers to engine output, horsepower and cc are two fundamentally different measurements. "Horsepower" refers to the approximate number of horses a healthy engine can do the work of. "CC" refers to the internal combustion space of the engine cylinders in cubic centimeters. Therefore, a 49cc engine clears out 49 cubic centimeters per sweep, resulting in a performance equivalent to the power of three horses.