Napier Lion

The Napier Lion was a twelve-cylinder, petrol-fuelled aero engine laid out as a broad arrow W12, with three banks of four cylinders sharing one crankshaft. D. Napier and Son built it from 1917 into the 1930s after the firm decided in 1916 to design its own high-power, light, narrow engine. Four valves per cylinder, twin overhead camshafts on each bank and an oversquare bore made it the most powerful engine of its day, and the first Lion I delivered 450 horsepower from 24 litres. It stayed in production long after rivals were superseded and powered more than 160 aircraft types between the wars, as well as record-breaking boats and the land speed cars of Malcolm Campbell and John Cobb.