Wright R-3350 Duplex-Cyclone
The Wright R-3350 Duplex-Cyclone is an American twin-row, supercharged, air-cooled, radial aircraft engine with 18 cylinders displacing nearly 3,350 cubic inches (54.9 L). Power ranged from 2,200 to 3,700 hp (1,640 to 2,760 kW), depending on model.
Source: Wikipedia — Wright R-3350 Duplex-Cyclone (CC BY-SA 4.0)