The Hispano-Suiza 18R was an eighteen-cylinder high performance water-cooled piston engine, in an 80° W or broad arrow layout, for use in racing aircraft, built in France during the latter half of the 1920s.

Each cylinder aspirated through two valves operated by single overhead camshafts with ignition from two spark plugs set on opposite sides of the combustion chamber supplied by magnetos at the rear of the engine.

Despite the effort put into its development the 18R proved to be unreliable and unable to achieve the expected power output.

Reducing the compression ratio to 6.2:1 at a maximum rpm of 2,000 and replacing the Elektron with aluminium alloy, the 18S was available with or without the Farman reduction gear, but was not a success, only powering the Ford 14A in the pylon mounted central nacelle.

[1] The 18R and 18S did not have successful careers, only powering four aircraft types in very small production numbers, proving to be totally outclassed by contemporary racing engines, such as the Rolls-Royce R which powered the Supermarine S.6 family of floatplane racers.