What is An Air Cooled Engine? | How does Air-Cooled Engine work?

The engine cooling system is one of the necessary thing that is present in the IC engine to reduce the temperature of the components inside the engine. It also helps to reduce the wear out of the component and provide smooth functioning and long life of the components. According to the cooling process: the engine is divided into the air-cooled engine and water-cooled engine categories. This article mainly explains the different aspects of an air-cooled engine.

What is Air Cooled Engine?

An air-cooled engine is a type of IC engine in which the air is passed over the engine to cool it. Air-cooled engines rely on the circulation of air directly over heat dissipation fins or hot areas of the engine to cool them in order to keep the engine within operating temperatures.

Air-Cooled Engine, air cooling system

In all combustion engines, a great percentage of the heat generated (around 44%) escapes through the exhaust, not through the metal fins of an air-cooling engine (12%). About 8% of the heat energy is transferred to the oil, which, although primarily meant for lubrication, also plays a role in heat dissipation via a cooler. 

Most modern cars use water-cooled engines with radiators, water pumps, and hoses that circulate a water and coolant mixture throughout the engine. The heat from the engine is transferred to the coolant, and then the coolant is cooled in the radiator and sent back around again.

Air-cooled engines want none of this. They rely on good old-fashioned air to cool them down. All engines are technically air-cooled because even water-cooled engines use air to cool the fluid in the radiator. But let’s not split hairs.

Air-cooled engines are generally used in applications that would not suit liquid cooling; as such modern air-cooled engines are used in motorcycles, general aviation aircraft, lawn mowers, generators, outboard motors, pump sets, saw benches, and auxiliary power units.

Working of Air-Cooled Engine

The air-cooled engine uses the air cooling system. The basic principle of the air-cooled engine is to allow air flow through the parts from which heat is to be dissipated, which depends upon the surface area of metal in contact rate of flow of air, a temperature difference between hot surface and air.

An air-cooling engine uses cooling fins cast into its cylinder head to dissipate heat instead of using a liquid-filled radiator. By eliminating the radiator, an air-cooled engine is able to be used in applications in which space restraints prohibit installing a radiator.

As the engine builds heat, the cooling fins allow the wind and air to move the heat away from the engine, much like a person blowing on a piece of food that is too hot to eat.

Construction of Air-Cooled Engine

Air-cooled engines have fins extending out from the engine to pull heat away. Cool air is then forced over the fins — typically by a car fan. For aircraft and motorcycles, the vehicle’s speed alone moves enough cool air over the fins to keep the engine cool.

air cooled engine construction

Some air-cooled engines may also have ducts around the engine to keep air flowing to the hottest areas. Some aircraft engines may even have baffling systems that channel high-pressure air into the cooling fins.

Another design feature that keeps an air-cooled engine’s temperature low is horizontally opposed cylinders — they face away from each other and are spread farther apart than a typical water-cooled engine. This allows air to flow freely over the fins. Some air-cooled engines also make use of oil coolers to keep the oil temperature low.

Air-cooled engines that operate at high engine speeds are 2-stroke engines. This type of engine uses a gas and oil mixture in the fuel tank, and the oil helps to cool the engine.

This type of configuration also eliminates a great amount of oil in the engine’s crankcase. The oil retains engine heat and adds to the cooling difficulties in a 4-stroke engine. This is why many 4-stroke engines require an external engine oil cooler to aid in maintaining proper temperatures.

Advantages of Air-cooled Engine

  1. Air-cooled engines don’t have coolant leakage problems.
  2. They warm up a lot faster than liquid-cooled engines.
  3. These types of engines don’t have any risk of coolant freezing.
  4. They’re lighter than liquid-cooled engines.
  5. They have a simple design.
  6. They don’t require
  7. This engine requires less installation space.

Disadvantages of Air-cooled Engine

  • Air-cooled engines are more likely to overheat.
  • The large fans used to cool the engine can take away a lot of power
  • They are more expensive to build.
  • This engine generates more noise than the oil-cooled engine.
  • The heat transfer coefficient of air is less, hence less efficient in working.
  • They require high maintenance.

Applications of Air-cooled Engine

  • An air-cooling system is generally used in small engines, say up to 15-20 kW, and in airplane engines.
  • The air-cooled engine is used in scooters.
  • They use in aircraft and motorcycles.
  • They use in recreational vehicles, cars, and tractors. 

Oil Cooled Engine Vs Air Cooled Engine

The main difference between the air-cooled engine and the oil-cooled engine is given below:

Oil Cooled EngineAir Cooled Engine
The oil-cooled engine uses oil as a cooling agent.The air-cooled engine uses air as a cooling agent.
These are most efficient engines than simple air-cooled engines.These are less efficient.
It has a low cost.It has more cost than oil-cooled engines.
It has a simple design than the air-cooling engine.It has a complex design.
These have easy maintenance.These have complex maintenance.
It has a radiator.It doesn’t use a radiator.

FAQ Section

Why do air-cooled engines have fins?

The air-cooled engines contain fins that extend out from the engine. The main function of these fins is to discharge the hot air of the engine into the environment. Then a fan blows fresh cooled air through the fins into the engine. In this way, the fins play a big role in maintaining the engine temperature.

Are air-cooled engines reliable?

Air-cooled engines work efficiently in RVs, motorcycles, and some airplanes. But when you use it for a car, generally it generates many problems, and it does more harm than good.

What are the advantages of Air-Cooled Engines?

The air-cooling engine doesn’t need antifreeze. It has a simple design and requires a low installation area. These types of engines are best for motorcycles, scooters, and some airplanes. They have low weight than liquid-cooled engines.

What are the examples of Air-Cooled Engine?

The air-cooling system is used on the engine, such as combat tanks, aeroplanes, motorcycles, and scooters.

Read More
  1. Different types of Engines
  2. Types of Reciprocting Engines
  3. Types of IC Engines
  4. Working of Oil Cooled Engine
  5. Types of EC Engines
  6. Working of Wankel Engine
  7. 2-stroke Engine Vs 4-stroke Engine

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