Napier Sabre

Napier Sabre cutaway at the London Science Museum.

The Napier Sabre was a British 24-cylinder, liquid cooled, sleeve valve, piston aero engine, designed by Major Frank Halford and built by Napier & Son during WWII. The engine evolved to become one of the most powerful inline piston aircraft engines in the world developing from 2,200 horsepower (1,640 kW) in its earlier versions to 5,500 hp (4,100 kW) in late-model prototypes.

The first operational aircraft to be powered by the Sabre were the Hawker Typhoon and Hawker Tempest; however, the first aircraft powered by the Sabre was the Napier-Heston Racer, which was designed to capture the world speed record[nb 1]. Other aircraft using the Sabre were the Martin-Baker MB 3 and some versions of the Blackburn Firebrand and Hawker Fury. The rapid conversion to jet engines after the war led to the quick demise of the Sabre, as Napier also turned to jets.

Source: Wikipedia