What is an air-cooled engine, and how does it work?

What is an air-cooled engine, and how does it work?

How do air cooled engines work; Porsche 911 993 and woman in suit.

If you say ‘air-cooled engine’ to a specific type of person, you might need to prepare yourself for a bit of a reaction.

Come across any Porsche aficionado – or even a Volkswagen fanatic – and they could possibly talk for hours about why the cars were better before a certain time – and why?

Because they had air-cooled engines…

While many might have heard about this power unit type before, some may wonder what all the fuss is about.

What is an air-cooled engine?

To be honest, this is a situation where it kind of does what it says on the tin.

An air-cooled engine relies on the natural flow of air to dissipate heat and cool its components during the combustion process.

In today’s vehicles, you’re likely to find them in motorcycles, small aircraft, while certain types of industrial equipment make use of an air-cooled engine.

However, most enthusiasts will look to the past when it comes to air-cooled engines – most notably in such lineages as the Porsche 911 line.

The late 1990s saw the discontinuation of the air-cooled Porsche 911, as the 993 generation gave way for the water-cooled 996.

Many saw the 993 line as the 911’s sweetspot, and so the transition from air- to water-cooled engines is seen as a bit of a sore point in the iconic sports car’s history.

Another German marque known for air-cooled engine implementation is Volkswagen.

VW’s air-cooled engines made their into the likes of the infamous Beetle (Type 1), as well as its original Transporter (Type 2) – you’ll also find air-cooled VW examples in a variety of light aircraft.

How do air-cooled engines work?

The general functionality of the air-cooled engine is fairly straightforward, which led to many of its benefits – here’s how one works on a basic level:

  1. Cooling fins – An air-cooled engine is equipped with cooling fins on its exterior surfaces, most prominently on its cylinder heads and cylinders themselves. These are in place to increase the surface area which is exposed to air.
  2. Natural Convection – As with all engines, heat is generated when in operation, and the cooling fins work to facilitate the transfer of heat from the engine’s components to the surrounding air.
  3. Airflow – Naturally, the air that is utilised for cooling is found whilst the vehicle is in motion. So, at speed, the engine is being cooled to a tolerable level – however, some air-cooled engines make use of fans or blowers to increase airflow at slow speeds or when the car is stationary.

Pros of an air-cooled engine

  • Simplicity: Fewer components lead to the air-cooled engine being quite a simple power unit option. This also brings the benefits of easier maintenance and lower repair costs.
  • Weight: The lightness of the air-cooled engine comes again from its fewer components, but also due to it not requiring a liquid cooling system like that of its water-cooled counterpart – this means no radiator, water pump or coolant.
  • Cold Weather Performance – You notice an air-cooled engine gets on better in cold weather compared to a water-cooled alternative, thanks in large to its ability to warm up quickly.

Cons of an air-cooled engine

  • Limited Cooling Capacity: There’s a reason the air-cooled engine isn’t half as prevalent as it used to be – this is largely down to a potential struggle to efficiently dissipate heat, especially so when the engine is being pushed. Overheating, as a result, can be a real issue.
  • Temperature Control: Or lack thereof – air-cooled engines don’t offer accurate temperature controls, and might affect its ability to perform optimally at times.
  • Noise/Vibration: An air-cooled engine’s lack of water avenues throughout the block and head usually lead to increased noise thanks to a lack of sound insulation.
  • Environmental Concerns: With the way an air-cooled engine operates, it could be that it creates a higher level of emissions and so have a greater impact on the environment.