What is 4 hp in cc?

The two are not related. CC(cubic centimeters) is a measure of piston displacement as is CI or (cubic inches). It is possible for various size motor diplacements to have the same horsepower. IE a 50cc motor as well as a 90cc motor theoreticall could have the same horsepower. (whatever that may be). Although, typically, the large the displacement, the more horsepower depandant on tuning.