i know everyones heard the age old comment and everyone has there own thoughts and opinions about it. share yours, i know this topic tends to lead to a immature "e-fight" so lets not go there with this thread. last time i put though into it, this is what i came up with. my thoughts- for the most part displacement is thought of as being equal to the volume of each of the engines cylinders. but, thats not the true definition of displacement. displacement is just what it sounds like, the amount of air an engine displaces during one cycle. on a 4 stroke, thats 2 revolutions. for naturally aspirated engines every 2 revolutions the amount of air pumped through the engine is directly related to the volume of the cylinders therefor its displacement can be said to be exactly that of the volume of its cylinders. for forced induction engines the amount of air displaced every 2 revolutions is not the same as the volumetric amount of its cylinders. Because air is being forced into the engine that air must also exit the engine. since the definition for displacement is the amount of air displaced by an engine during 2 revolutions and a forced induction engine processes more air per every 2 revolutions than the volumetric amount of its cylinders the engine's displacement and cylinder volume are not directly related. with that truth said, one more truth needs to be addressed. Since the amount of air processed by an engine directly relates to the amount of fuel an engine can process, the more an engine displaces the more powerful it may be. Therefore, there is no replacement for displacement.