Thursday, August 2, 2012

VW Idiosyncrasies: How an Air-cooled Engine Works in General.

Before we go on further with our Volkswagen adventure, it would be best also to touch first on the idiosyncrasies of this iconic vehicle. Of course we all know that the Volkswagen Beetle is one of the world’s most recognizable automobiles because of its signature body shape, unusual rear engine placement and of having an air cooled engine. I guess all VW enthusiasts know what an air cooled engine is. This is just a general, simple and short article for the uninitiated. 

These engine fins are not for decorations but serve a purpose in  cooling down the air cooled engine

Air-cooled Engine Experience.

Nowadays you usually get to experience riding an air-cooled engine through your beloved VW vehicle, on a motorcycle (some motorcycles are water-cooled), on all-terrain vehicles, or even a common riding mower. What remained air-cooled from the beginning up to the present though are aircrafts like many helicopters and small planes.
Though some carmakers used air-cooled engines to power their vehicles in the 1960s and 1970s, air-cooled engines won’t go back to their glory days in the assembly line these days. Everyone knows that it was used in the original Beetle but how does an air-cooled engine actually work compared to water cooled engines we now commonly use?

How it Works.

Simply put, a water-cooled engine uses water (with or without coolant mixture) to cool the engine. Modern cars use water-cooled engines with radiators, water pumps and hoses that circulate water throughout the engine. The heat from the engine is transferred to the water, cooled in the radiator and circulates again.
An air-cooled engine is simpler: It allows air flow over the engine to keep it cool. They have fins extending out from the engine to pull heat away then cool air is forced over the fins through a fan in cars. With aircraft and motorcycles, the vehicle's speed alone moves enough cool air over the fins to keep the engine cool.

In general, these engines may have other design features to help keep the engine cooler like ducts to direct air flow to hotter areas, baffling systems (in airplanes) to channel high-pressure air into the cooling fins, horizontally opposed cylinders (faced away from each other) and spread farther apart than a typical water-cooled engine allowing air to flow over the fins, oil coolers to keep the oil temperature low, etc

Continental R-975 air-cooled, nine cylinder radial engine from the HUP-2 helicopter (image courtesy of Marcel Crettet).
Advantages and Disadvantages of Air-cooled Engines
1. Doesn’t have water leakage problems. 
2. Won’t require replacement of parts like the water pump or radiator.
3. They’re lighter than liquid-cooled engines, too, because they have fewer parts.
4. Warm up a lot faster than liquid-cooled engines
5. Don’t have any risk of the coolant freezing, beneficial  in extremely cold temperatures.
1. Air-cooled engines are more likely to overheat. 
2. The large fans used to cool the engine can take away a lot of power.

On cars, the common consensus is that the disadvantages outweigh the advantages. They work extremely well  though for motorcycles, recreational vehicles and certain aircrafts.  

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