What is in spark? If you consider the thing in terms of ignition, a spark from the spark plug helps in igniting the fuel. This is the statement which is emphasizing and proclaiming about the term called as spark. Here we got the next question. We got to tell about the number of cylinders in IC engine. The number of cylinders actually is going to be very based on the operation. They vary from a cylinder cylinder engine to an 18 cylinder engine that may be a Rolls Royce.