How a rotary Wankel engine works

Working of Rotary Wankel engine

Here is the complete guide about Rotary Wankel engine. Here you can get rotary Wankel engine working, main Parts, Advantages and Disadvantages ect.

The first Wankel engine was developed by German engineer – Felix Wankel. Wankel received his first patent for the engine in 1929.
However, the Wankel engine design used today  is designed by Hanns Dieter Paschke – which he adopted forming the modern engine.

rotary engine is an indoor combustion engine, just like the engine in your car, but it works during a completely different way than the traditional piston engine. In a piston engine, the same volume of space (the cylinder) alternately does four different jobs — intake, compression, combustion and exhaust. A rotary engine does these sam­e four jobs, but all happens in its own part of the housing. It’s quite like having a dedicated cylinder for every of the four jobs, with the piston moving continually from one to the next. The rotary engine (originally conceived and developed by Dr. Felix Wankel) is sometimes called a wankel engine, or Wankel rotary engine.

Wankel engine

Wankel engine is an internal combustion engine unlike the piston cylinder arrangement. This engine uses the eccentric rotor design which directly converts the pressure energy of gases into rotatory motion. While within the piston-cylinder arrangement, the linear motion of the piston is used to convert into rotatory motion of crankshaft.

Basically, in a simple way, the rotor revolve in housings shaped during a fat figure-of-eight.

Working of Rotary Wankel engine

Intake :-
When a tip of the rotor passes the intake port, fresh mixture starts entering into the first chamber. The chamber draws fresh air until the second apex reaches the intake port & closes it. At the moment, fresh air-fuel mixture is sealed into first chamber & is being taken away for combustion.

Compression :-
The chamber one(between corner 1 to corner 2) containing the fresh charge gets compressed due to shape of the engine by the time it reaches to sparking plug .
While this happens, a new mixture starts getting into the second chamber(between corner 2 to corner 3).

When the spark plug ignites, the highly compressed mixture expands explosively. The pressure of expansion pushes the rotor in forward direction. This happens until the primary corner passes through the exhaust port.

Exhaust :-
As the peak OR corner 1 passes exhaust port, the recent high combustion gases are liberal to effuse of the port.
As the rotor continues to maneuver , the quantity of chamber goes on decreasing forcing the remaining gases out of port. By the time the corner 2 closes the exhaust port, corner 1 passes by the intake port repeating the cycle.

Parts of a Wankel engine


The rotor has three convex faces which acts like a piston. the three corners of rotor forms a seal to the outside of the combustion chamber. It also has internal gear teeth within the centre on one side. this enables the rotor to revolve around a fix shaft.


The housing is epitrochoidal in shape(roughly oval). The housing is cleverly designed because the 3 tips or corners of the rotor always stay in touch with the housing. The intake and exhaust ports are located within the housing.

Inlet & exhaust ports

The intake port lets fresh mixture enter into combustion chamber & the exhaust gases expel out through outlet/exhaust port.

Spark plug

A spark plug delivers electric current to the combustion chamber which ignites the air-fuel mixture resulting in abrupt expansion of gas.

Output shaft

The output shaft has eccentric lobes mounted thereon, which means they’re offset from
centreline of the shaft. The rotor isn’t in pure rotation, but we’d like these eccentric lobes for pure rotation of the shaft.


  • wankel engine has a very few moving parts; far less than 4 stroke piston engine. This makes the design of the engine simpler & the engine reliable.
  • it’s approximately 1/3rd of the size of the piston engines delivering same power output.
  • ready to reach higher revolutions per minute than a piston engine.
  • wankel engine weighs almost 1/3rd of the load of the piston engines delivering same power output. This results in a better power to weight ratio.


  • As each section has temperature differences, the material expansion of housing is different at different region. Therefore, the rotor is unable to completely seal the chamber in high temperature region sometimes.
  • The combustion is slow because the combustion chamber is long, thin, and moving. Hence, there could be a possibility that the fresh charge discharges out without even burning.
  • As unburnt fuel is within the exhaust stream, emissions requirements are difficult to meet.

Rotary Engine FAQ

How does a rotary engine work?

A rotary engine is an indoor combustion engine that separates an engine’s four jobs — intake, compression, combustion, and exhaust — into four individual parts within the overall engine housing. The rotor moves from chamber to chamber, expanding and contracting gas.

Why are rotary engines bad?

There are a couple of disadvantages of rotary engines. It’s harder to make a rotary engine meet U.S. emissions regulations, and the manufacturing costs are often higher. Rotary engines also tend to consume more fuel than piston engines.

Is a rotary engine better?

Rotary engines do have some advantages over other engine types. they will be more reliable because their parts and pieces move at a slower speed. they will also operate more smoothly, eliminating the violent direction changes in piston engines. And rotary engines tend to have fewer moving parts overall.


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