Home ENGINEERING Mythical Boxer Engine Of The Citroen 2CV Animation

Mythical Boxer Engine Of The Citroen 2CV Animation


In this video we analyze the mythical boxer engine of the Citroen 2CV and we discover why it is so good. Its manufacture lasted more than 40 years for the reason that we will watch today.The engine was designed by Walter Becchia and Lucien Gerard, with a nod to the classic BMW boxer motorcycle engine.

source.image: Repairman22

It was an air-cooled, flat-twin, four-stroke, 375 cc engine with pushrod operated overhead valves and a hemispherical combustion chamber. The earliest model developed 9 PS (8.9 bhp; 6.6 kW) DIN.The 2CV used the wasted spark ignition system for simplicity and reliability and had only speed-controlled ignition timing, no vacuum advance taking account of engine load.Watch the video from Repairman22:

The inlet and exhaust manifolds were welded together into a single unit, with exhaust pipe and inlet tract abutting each other directly under the carburettor at an enlarged ‘heat chamber’. Heat from the exhaust warmed both the metal and the air/fuel mixture inside the chamber, ensuring full vaporization of the fuel for greater combustion efficiency.


Unlike other air-cooled cars (such as the Volkswagen Beetle and the Fiat 500) the 2CV’s engine had no thermostat valve in its oil system. The engine needed more time for oil to reach normal operating temperature in cold weather. All the oil passed through an oil cooler behind the fan and received the full cooling effect regardless of the ambient temperature.