The Franklin O-540 (company designation 8AC) was an American air-cooled aircraft engine that first ran in the early-1940s. The engine was of eight-cylinder, horizontally-opposed layout and displaced 540 cu in (9 L). The power output was nominally 300 hp (224 kW).

Variants

8ACG-538 (XO-540-1)

Geared propeller drive at 0.632:1, 300 hp (224 kW) at 3,200 rpm

8ACSA-538 (XO-540-7)

Supercharged, 300 hp (224 kW)

8ACGSA-538 (XO-540-3/O-540-5)

Supercharged and geared,330 hp (246 kW) at 3,200 rpm

Applications

• Northrop N-9M

Specifications (8ACG-538/XO-540-1)

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General characteristics

• Type: 8-cylinder air-cooled horizontally opposed aircraft piston engine
• Bore: 4.625 in (117.5 mm)
• Stroke: 4.0 in (101.6 mm)
• Displacement: 537.6 in³ (8.8 L)
• Dry weight: 438 lb (199 kg)

Components

• Cooling system: Air-cooled

Performance

• Power output: 300 hp (224 kW) at 3,200 rpm