Rotary Engine

What’s A Rotary Engine or Wankel Engine & How It Works?

 | 4 minutes read

Rotary Engine or Wankel Engine:

A rotary engine or Wankel engine is a type of internal combustion engine. In this design, it is the crankshaft that remains stationary while the triangular rotor rotates. Unlike conventional engines, rotary engines have the arrangement of the cylinder moving around a fixed crankshaft.

Rotary Engine
Rotary Engine

The rotary engine uses the combustion of the fuel to spin a triangular rotor around the central driveshaft. This engine successfully does away from the piston type and provides the crankshaft. These engines are perfectly balanced and very refined. Felix Wankel invented one of the most popular types of rotary engines. It has been employed in the powerful and famous Mazda sports cars. It is the most talentedly designed internal combustion engine of modern times.

The rotary engine is not as efficient as the piston engines. It has undergone research and for the development throughout the century all over the world. The main factors that make the rotary engines successful are smooth running, fewer parts and low weight. The rotary engine delivers a very smooth power because of less reciprocating parts while it delivers large rotating motion.

It has a low weight advantage as well. It is a very conventional engine that has the heavy flywheel which stores the energy in pulses and also reduces the vibrations. The rotary engines gain substantial power-to-weight ratio for not needing to add the flywheel. This engine rotates the cylinder block and creates its own speedy moving cooling airflow while running.

Wankel Engine:

Dr. Felix Wankel invented the rotary engine. So, it is popularly known as the Wankel engine. This design has an eccentric curved housing. However, it has a triangular-shaped rotor moving inside it.

Furthermore, the Wankel engine is an internal combustion engine that uses an eccentric rotary design. It converts the pressure into a rotating motion. Among all the engine design and classifications, the Wankel engine has maximum advantages. It offers benefits such as compactness, smoothness, and simplicity. This type of engine offers more revolutions per minute or high speed, which gives more performance. Wankel engine also has a high power-to-weight ratio.

Furthermore, all the Wankel engine components rotate in a single direction. The main advantage of this engine is that it has a compact design. These engines have multiple applications. A variety of vehicles and machines use the rotary engine. These include racing cars, automobiles, aircraft, motorcycles, go-karts, snowmobiles, jet skis, and auxiliary power units.

 Rotary Engine operation
Rotary Engine operation

Moreover, it can also be used in personal watercraft for aircraft. It does not suffer from scaling effects, which other engines do due to limiting their size. The Wankel engine is capable of using fuels with a wider octane rating. It is more efficient than a piston engine as it reaches more revolutions (speed) per minute. The engine contains fewer parts. It does not have any reciprocating part in it which reduces the cost of mass-production.

Rotary Engine Advantages:

  1. Smaller in size, lighter in weight and more compact compared to reciprocating engines.
  2. Cheaper and simple in construction for mass-production
  3. Absence of many parts such as connecting rods, camshaft, and valve mechanism, etc.
  4. Easier to the balance due to less number of parts
  5. High volumetric efficiency (usually more than 100%)
  6. High power-to-weight ratio
  7. Low running cost
  8. Does not require the overdrive as the speed of the engine itself is very high


  1. High fuel consumption at low speeds
  2. Lower torque values
  3. Higher engine oil consumption
  4. The braking effect of the engine is very less
  5. Speed reduction in the gearbox is necessary due to high engine speed
  6. Spark-plugs need frequent replacement in older/ordinary ignition systems
  7. Poor sealing issues in the older designs

Mazda employed the rotary engine in its Mazda RX series cars.

Watch Rotary engine / Wankel engine in action here:

[Youtube vid=6BCgl2uumlI]

Read more: > (opens in a new tab)">What is a 'V' engine & how it works?>>

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