Harry Ricardo founded the company as Engine Patents Limited in February 1915. During the First World War it helped develop an engine for a flying boat and then a four-stroke crosshead engine for the Mark V tank. By 1919 it had a laboratory at Shoreham-by-Sea, and it became Ricardo and Co. In the 1920s it developed the turbulent head side-valve engine, and in the late 1920s a six-cylinder diesel built by AEC as the Comet and taken up by makers across Europe, including Citroen.
In 1938 it developed the V-16 engine for the streamlined Alfa Romeo Tipo 162. In the Second World War it worked on the Barostat fuel valve used on Frank Whittle’s jet, and later it pioneered Stirling engines for cars on behalf of the US Department of Energy. In 1986 it redesigned the engine for the Rutan Voyager, the first aircraft to fly round the world without refuelling.
More recently Ricardo developed the McLaren M838T 3.8-litre twin-turbo V8 for McLaren supercars, and its combustion technology went into the JCB Dieselmax that set a diesel speed record of 350 mph in 2006. It is based at Shoreham-by-Sea in West Sussex, and was bought by the Canadian consultancy WSP Global in October 2025.
