Air-cooled vs water cooled engine


Most likely your modern car has a water-cooled engine. When an internal combustion engine operates, it creates high amount of heat. Unless there is a mechanism to dissipate the heat, it will damage the engine components. In modern automobile engines, a coolant system is used to keep the engine cool. Usually a chemical coolant is used (although named water cooled, water is not used anymore now as coolant) within a sealed system (you rarely need to top up). The cooling system creates a jacket outside the engine. It also keep the engine in constant temperature. The proof is your car’s temperature gauge which usually stays halfway to H and C mark.

In air-cooled engine, air is used to cool the engine down. Thus, it does not require radiator and cooling system – which makes the whole engine a lot simpler. It uses radiator fins (easy to see in motorcycles) which are used to cool the engine. But there are drawbacks too. Unless there is steady flow of air, the engine may get overheat quickly. They are also very noisy as the radiators fins vibrate when engine is in operation.

Air-cooled engines are used mainly in motorcycles, some 3-wheels (like India’s Bajaj autorickshaws), some cars (classic VW Beetle, old Porsches etc.) and some propeller aircrafts.

For aircrafts, they are not a big problem. Unlike a car, an aircraft does not get stuck in traffic jams. Aircraft engines operate within their 80-100% RPM range most of the time and due to high speed cruising plenty of air pass over the radiator fins to keep them cool. This also explains why old propeller aircrafts with such engine sound so loud.

But problem might happen in air-cooled car engines! If the car is stuck in traffic or moving slowly over extended period of time, the engine may overheat (which may lead to seizure of engine).  On the other hand, they are quite good at cold weather condition as chance of overheating is lower.

 

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One Response to “Air-cooled vs water cooled engine”

  1. Eric Shupps Says:

    Excellent post. Very helpful. Thanks for the info.

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