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FIAT A.74

The Fiat A.74 was a two-row, fourteen-cylinder, air-cooled radial engine produced in Italy in the 1930s. The A.74 was important in that it marked a transition for Fiat from liquid-cooled inline engines, to large air-cooled radial engines. Fiat had made a number of smaller radial air engines over the years but the A.74 marked a major increase in power and size. The A.74 family was widely produced and spawned a number of related engines such as the A.76, A.80, and A.82. Each successive generation being larger and more powerful than the previous. The entire series grew from 14 cylinders to 18 cylinders with a power output of 870 hp to 1,400 hp.

Manufacturer: Alfa Romeo
Developed: 1930s
Type: 14-cylinder air-cooled radial
Bore: 140 mm (5.512 in)
Stroke: 145 mm (5.709 in)
Displacement: 31.25 L (1,906.9 cu in)
Length: 1,044mm (41.13 in)
Width: 653mm (25.71 in)
Height: 1,195 mm (47.05 in)
Dry weight: 565 kg (1,246 lb)
Components:
– Valvetrain: One intake and one sodium-cooled exhaust valve per cylinder
– Fuel system: 1 Stromberg carburettor
– Fuel type: 87 octane
– Cooling system: air-cooled

Performance:
– Take-off power: 858 hp at 2,520 rpm at sea level
– Emergency Power: 947 hp at 2520 rpm at 3,000 m
– Compression ratio: 6.7:1
– Power-to-weight ratio: 0.67 hp/lb

Variants:
The Italian engine designation system includes a suffix indicating major components or attributes. The most common were R for Riduttore - reduction gear and C for Compressore - compressor/supercharger, followed by a number indicating the rated altitude in hundreds of metres, two speed superchargers were indicated by a double figure such as 10/34.

A.74 R.C.38
With reduction gear and supercharger, rated altitude 3,800 m (12,500 ft).

A.74 R.I.C.38
With reduction gear, fuel injection and supercharger, rated altitude 3,800 m (12,500 ft).

A.74 R.C.42
With reduction gear and supercharger, rated altitude 4,200 m (13,800 ft).

Applications:
– CANSA FC.20
– Fiat CR.42
– Fiat G.50
– Fiat RS.14
– Macchi C.200
Sources:
Bridgman, Leonard (ed.) (1938). Jane's All The World's Aircraft 1938. London: Sampson Low and Marston Co. Ltd.
Gunston, Bill (1986). World Encyclopedia of Aero Engines. Wellingborough: Patrick Stephens.
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