An air-cooled engine is one with many precision parts moving in high-speed synchronization, akin to an Audemars Piguet running on high octane fuel. Air-cooling offers advantages in simplicity, lightweight, and low cost. Truth be told, automotive air-cooled engines are basically cooled by both air and oil.
The fins on the cylinders and cylinder heads expose as much surface area as possible to the cooling air forced across them by an engine-driven fan, on the other hand, the heat exchanger which is situated in the airstream controls the temperature of the engine oil. An oil pressure valve controls the flow of oil through the cooler only when the viscosity drops below a pre-determined threshold, indicating that the oil has reached operating temperature.
A major setback for this engine was the introduction of supplementary external oil cooling in the form of remote heat exchangers for engine output around 100 kW (135 DIN hp).this development diminishes the cost and weight-saving advantages of the original air-cooled engines.
The Porsche 356 is a clear example as its 4-cam Fuhrmann engine used two such remote oil coolers mounted in front behind the horn grilles. The 911 incorporated a much larger integral cooler mounted on the crankcase; nonetheless, even in original 2.0-liter form, Porsche recommended fitting an additional cooler when using the car for “Sports Purposes.” As the power output of the 911 steadily increased, a front-mounted cooler eventually became standard fitment.
The decade of the sixties represented the peak of development of air-cooled engine designs, with significant advancements over those created earlier. Most of these engines reflected the latest design currents of the time with overhead camshafts, hemispherical combustion chambers, and the ability to rev to 7,000 rpm or higher. Let take a look at some of the brands with air-cooled engine formations as well as their performance.
NSU 1000 (1963-1973)
See also, Auto Insurance Who Does Auto Insurance Coverage Protect
NSU Prinz 1000 launched in 1963 was the world’s first inline four-cylinder to incorporate air-cooling since the ill-fated 1923 Chevrolet, and the first mass-produced air-cooled automotive engine with an overhead camshaft.
The engine was constructed of an aluminum block with two sets of iron cylinders cast in pairs, and a pair of twin-cylinder heads. The cooling fan was built into the flywheel and a single overhead camshaft was driven by a chain from the nose of the crankshaft. 1.0, 1.1, and 1.2-liter versions were built. The engines were mounted transversely behind the rear axle.
Its strong and rigid crankshaft was supported by five main bearings. Soon after introduction, the sporting TT variant was launched with twin carburetors and later the fabled TTS. Both TT and TTS versions would spin up to 7000 rpm in stock form as this made them the favorite by sedan racers of the period, facing off against Mini-Coopers and Fiat-Abarths. The NSU’s won many European Touring Car Challenge Division One award including 1st at Spa in 1967 and 1971 and 2nd at Zandvoort in 1968 and 1970. They also achieved class victories in the 1968 Marathon de la Route and the 1974 German Hillclimb Championship.
1936 Tatra T97
Air-cooling technology was quite rare before World War II as only the Czechoslovakian Tatra flat-four and V8 and the VW flat-four were being produced in 1940. Following the war, both Tatra and VW restarted manufacturing of their air-cooled engines. The original Tatra V8 stayed in production through 1975 and the prewar VW flat-four powered the Beetle until the autumn of 1960, at which time it was replaced with an updated air-cooled engine design.
After the war, Citroën and Panhard joined the air-cooled club with the 2CV and Dyna X and the Porsche 356 débuted with a redesigned version of the VW engine. A number of Japanese and Eastern Block manufacturers introduced air-cooled models and numerous small cars were powered by modified one and two-cylinder air-cooled motorcycle engines. Nuova 500 was introduced by Fiat produced under license in Austria by Steyr-Puch who developed their own engine for the car. Horizontally opposed air-cooled twin with hemispherical combustion chambers came on board. The Group 2 European Rally Championship in 1966 was won by Styer-Puch 650TR.
Chevrolet was not left out in the business as it introduced the Corvair with a horizontally opposed air-cooled six-cylinder engine in 1959. DAF released their 600 featuring an air-cooled flat-twin.
Porsche 911 (1964-1998)
Read also, Things you should Know About Porsche’s New 911 GTS Model Range
With Paul Hensler and Hans Mezger at the herm of Porsche 911 design, the Porsche 911 of 1964 became the most iconic air-cooled engine among enthusiasts. The duo had to topple both the standard 356 engine and the 4-cam Furhmann engine, the horizontally opposed six-cylinder was originally produced as a 2.0 liter with an aluminum crankcase and aluminum cylinder barrels with cast-iron liners. Each cylinder was topped with its own aluminum cylinder head with a fully machined hemispherical combustion chamber. The single overhead camshafts were chain-driven. Cooling was provided by a belt-driven cast magnesium fan surrounding the alternator. The air ducting was molded from fiberglass-reinforced resin.
The crankcase had a dry sump, with a single dual-chamber pump handling both pressure and scavenging functions. An eight-liter oil reservoir and full-flow filter were located behind the right-rear wheel. In 1970, oil spray jets were added to cool the underside of the pistons, a feature that became commonplace on turbocharged engines in the years following.
The E and S versions that came with fuel injector and electronic ignition were upgraded from the original 2.0 liters to 3.6 liters and were developed in both normally aspirated and turbocharged form. with this development, they took the world by storm winning every major race in the world in which it entered including the Monte-Carlo Rallye in 1968, 1969, 1970, and 1978, the Tour de France in 1970, the Targa Florio in 1966, and 1973, and Le Mans in 1979.
Read more on belmadeng.com