This is quite a difficult question to answer, as there are lots of factors involved, but as a general rule of the thumb, you would multiply the horsepower by between 10 to 15 to get the number of CCs. The reason why this is a difficult question to answer is because of two main reasons. The first is, that CCs and horsepower are two separate things. CC refers to the volume of the engine, whilst horsepower refers to the power output of the engine. Trying to convert volume into power, without knowing any other details, is nearly impossible. It would be like, trying to work out someone's weight by knowing what their hair colour is. Secondly, even though, there is a very rough formula for working out horsepower from CCs, there are far too many factors involved to provide an accurate general formula. The power output of an engine, is determined, not only by the volume size of the engine, but also the efficiency of the engine, the cleanliness, the quality of the components, the age, if the engine has a booster or some other performance enhancing mechanism, as well as many other minute and large factors. Basically, there are too many variables. The best way to find out what BHP (brake horsepower) output your vehicle has, you should contact the manufacturer of your vehicle, as they will have a record of how many BHP are there in your vehicle. However, factors such as age, wear and tear, dirt etc. Affect the power output of an engine, so a power test on a running road would be required to get a totally accurate read-out of BHP that your vehicle produces. In a modern car, one cubic inch of engine volume can equate to 1 brake horsepower, but this again, is an estimate.
