Four cylinders are four, six cylinders are six.
The manual of a gasoline car will indicate how many cylinders the car has. Generally, there are as many spark plugs as there are cylinders in the car.
The spark plug gasoline engine ignition system introduces high voltage current into the cylinder to generate electric sparks to ignite the combustible mixed gas components. It is mainly composed of wiring nut, insulator, wiring screw, center electrode, side electrode and shell, and the side electrode is welded to the shell.