The phrase "extra cylinder" refers to an additional unit or component, usually in the context of an engine. It means adding another cylinder to the engine, which allows it to generate more power or perform better. Full definition
Even still, it is comedy gold that a stretched Beetle with a couple of extra cylinders still goes into battle against V10 and V12 monsters, and often victorious! (autocar.co.uk)
Hard to say, but this thing desperately needs a turbocharger or a couple extra cylinders. (autoweek.com)