The Engine Capacity is the combined capacity for all cylinders of the engine added together while it completes its one complete cycle. For example, if a four cylinder engine has capacity of 1000cc or 1.0L; that means all the four cylinders can together accommodate a maximum of 1000 cubic centimeters or 1.0L of volume of air in them. If the engine has only one cylinder, then that lone cylinder will accommodate all of the 1000cc or 1.0L of air inside it.
The ‘Engine Capacity’ is the volume, in other words; the space available inside the cylinder to accommodate air-fuel mixture for burning. As the volume of the air grows, the corresponding quantity of fuel supplied to the engine is also proportionately increased. As the amount of the fuel for burning increases, it results in higher poweroutput. Hence, in simple words, the power output of an engine is directly proportional to the engine capacity in a conventional engine design.