Air-cooled engine

Air-cooled designs are far simpler than their liquid-cooled counterparts, which require a separate radiator, coolant reservoir, piping and pumps.

[1] Air cooled engines usually run noisier, however it provides more simplicity which gives benefits when it comes to servicing and part replacement and is usually cheaper to be maintained.

Few current production automobiles have air-cooled engines (such as Tatra 815), but historically it was common for many high-volume vehicles.

In 1921, the US Navy, largely due to the efforts of Commander Bruce G. Leighton, decided that the simplicity of the air-cooled design would result in less maintenance workload, which was paramount given the limited working area of aircraft carriers.

Leighton's efforts led to the Navy underwriting air-cooled engine development at Pratt & Whitney and Wright Aeronautical.

[4] In the late 1920s into the 1930s, a number of European companies introduced cooling system that kept the water under pressure allowed it to reach much higher temperatures without boiling, carrying away more heat and thus reducing the volume of water required and the size of the radiator by as much as 30%, which opened the way to a new generation of high-powered, relatively low-drag liquid cooled inline engines such as the Rolls-Royce Merlin and Daimler-Benz DB601, which had an advantage over the unpressurized early versions of the Jumo 211.

At the time, Union Carbide held a monopoly on the industrial process to make glycol, so it was initially used only in the US, with Allison Engines picking it up soon after.

In these roles, the simplicity and reduction in servicing needs is far more important than drag, and from the end of the war on almost all piston aviation engines have been air-cooled, with few exceptions.

BOMAG part of the FAYAT group also utilizes an air cooled inline 6 cylinder motor, in many of their construction vehicles.

Subsequent to their initial production which was exported worldwide, other companies took up the advantages of this cooling method, especially in small portable engines.

Applications include mowers, generators, outboard motors, pump sets, saw benches and auxiliary power plants and more.