The Most Interesting Engine In The World 😍 Citroen 2CV / How does it work in 3D?

In today's video we will analyze the immortal  engine of the Citroën 2 CV. We will see why this engine should be studied in any engineering  university, and the keys that made it brilliant. We will compare it with its German  rival and see which is the best.

alloy-based engine and finned cylinders, cooling  was by an axial fan connected to the crankshaft. The compression ratio was interesting.  From 6 to 1 and with its squared bore and stroke ratio it could exceed  3500 RPM delivering 9 horsepower.

Torque was only 15 lb-ft, but  enough to move the 1000 lbs car. The 1950 Beetle, which it was competing  against at the time, had 4 cylinders, with 1131cm3 and a compression ratio of  5. 6 to 1.

Delivering 25 HP @ 3300 RPM. The ratio of power per cubic centimeter  falls in favor of the Citroën by very little. The Beetle uses the classic and simple gear oil  pump, while the 2CV goes to a modern Gerotor pump.

The central part of 4 teeth rotates  directly connected to the camshaft. with the 5 teeth of the external rotor,  positive displacement is generated Compared to a gear pump,  the gerotor pump is quieter, has fewer vibrations and is more efficient. However, the gear pump is not far behind,  being simpler to design and cheaper.

Both pumps are very easy to repair as  they only consist of 2 moving parts. The oil is absorbed by an oil  pick up tube in the crankcase, goes up through a conduit to the pump, and then  is forced under pressure inside the camshaft, and also through the veins  of the crankshaft. Not all, but one version even brought channels on  the connecting rods to lubricate the pin.

The copper pipes carry oil to the rocker  arms of the valves in the cylinder head. The aluminum oil cooler is located just behind the  fan and doesn't clog other cylinders like it does on the Beetle, which has cylinder number 3 with  the spark gap slightly delayed to compensate extra heat and the possibility of knocking. In addition, the Beetle has a centrifugal fan  attached to the large duct that directs air into the cylinders.

This causes the  air to change direction, increasing resistance and decreasing efficiency. The axial fan pushes straight. There is no chain or belt.

The  gears keep the engine in sync. The camshaft drives the valves  by rods and rocker arms. Through this nut the valve clearance is adjusted The angled valves significantly improve the flow of gases since it does not collide with the  cylinder walls, and the hemispherical combustion chamber improves efficiency.

The exhaust valve  is intentionally in the front. This is so that the air from the fan concentrates all its power on  the hottest part, and then, in addition, the warm air goes towards the rear, heating the intake and  having an even temperature throughout the engine. The hot intake ports prevent fuel drops from  sticking to the walls, evaporating it and reaching the cylinder in gaseous form, mixing better  with air and obtaining superior combustion.

In addition, the exhaust pipes also pass  through the carburetor to heat it up. Although today intake air is preferred as cold  as possible to increase its density and improve power, at that time, where electronic injection  did not exist, the best thing was to heat the air. The hemispherical combustion chamber is  complemented by a very interesting piston.

It has a cut for maximum valve opening  and lateral shoulders to avoid losing compression caused by the well in the center. On the Beetle, the cylinder head has straight valves which make it cheaper and easier to  build, although it does slightly reduce air flow. The combustion chamber is of the  inverted bath tub type.

It reduces knocking and is cheaper to build than the 2CV. In both cases, the cylinders are removable, and when they wear out, it was enough to take  them to the shop and exchange them for already repaired parts with new pistons, speeding  up the process with no dead waiting times. The connecting rods are of a single piece,  without caps or bolts.

How were they placed? Well, One of the most interesting things is the crankshaft of the 2CV. It is made up of assembling parts to fit the connecting rods.

This makes machining the  crankpins really easy as they fit into a little bench lathe. It is not necessary to  have a large one like the current crankshafts where the complete piece rotates, although  to be honest, since it is a disassembled crankshaft, its resistance decreases. However, the small 375 cm3 engine only produced about 9 horsepower and its speed was  limited to 70 kilometers per hour or 45 mph There is no conventional distributor.

The Spark  Jump is commanded by a rotor with centrifugal advance on the camshaft at the front. This  means that every time the piston reaches TDC, the coil fires a spark in both cylinders,  regardless of whether it is the right time. In other words, the spark plug has twice the wear  and therefore lasts half as long.

This was done to save cost and not to place the distributor. Its name is Wasted spark system. The generator was 6 volts, and later it  was changed to a 12 volts alternator.

The flywheel is large and heavy  to keep the engine rotating. Being only 2 cylinders, there is only one  combustion per turn of the crankshaft. During the compression and exhaust stroke of each  cylinder respectively, there is no one to drive the engine.

Only inertia kept it rotating. This makes the engine lose agility when one seeks to accelerate quickly. The Beetle is a 4 cylinder and there is always a combustion stroke driving the engine.

By using a crank, the same one used to change wheels, the engine can be  started if there is no battery. Finally, in the upper part of the engine we  find the carburetor and also the oil fill port, which at the same time has a venting filter or  crankcase breather. Let's remember that when the pistons come together in the crankcase, its volume  decreases and that pressure must be released somewhere, otherwise, the seals and gaskets of  the engine will explode, spitting oil everywhere.

Later, the engine received modifications and  grew to 425cm3, reaching 18 horsepower, Then, to 602cm3 with 28 horses. Enough  to exceed 110 km/h or 70 mph . The 2cv had been designed for driving in rural  France where there were virtually no roads.

Its mechanical suspension using  friction dampers made it very simple. You basically couldn't lose hydraulic fluid. The wiper blades are powered by the speedometer  wire.

The faster you go, the more it cleans. Basically an automatic wiper. The bad thing is  that if you stop completely, it stops working.

The headlights are adjustable  from the inside by a rod. The Beetle, although it also had  good off-road capability, was more intended for the German highways. Just as the Thing also existed, Citroën had the Mehari version.

Of  which many units were manufactured. The 2CV van was also very popular for delivery. Nor can we ignore the Sahara version, which had 4 wheel drive thanks to the  placement of a second engine in the rear.

It had 2 fuel tanks. One under each  seat for each engine, and also, all the commands were duplicated, and by moving  the gear stick or pressing the accelerator, one was actually driving 2 engines. This version is easily distinguished by the fan that breathes through the trunk  door and the spare wheel on the hood.

Only in Argentina, in 1967, the 2CV was renamed  3CV by idea of the marketing department. It was done to highlight the evolution of  the model and that it had been improved compared to previous years. In the rest of  the world, it continued to be called 2CV.

The manufacture of this vehicle  started in 1949 and ended in 1991. It remained for more than 40 years  and approximately 5 million units were sold among its variants.  Well below the Beetle or the Ford T But enough to stay among the  most important vehicles in history.

Have you ever traveled in a Citroën 2CV? You can always support me by leaving a super thank of the value you want or if not, by  pressing the like button. Comment your experience with these air-cooled engines and don't forget to  follow me on my other networks.

See you next time.