Ricardo plc

The company was established in February 1915 by Harry Ricardo under the name Engine Patents Limited. During the First World War, the firm focused on military applications, including the development of a 600 brake horsepower piston engine for a flying boat and a device for maneuvering 25-tonne battle tanks onto railway wagons. In 1916, the company designed a 150 brake horsepower four-stroke crosshead-type engine for the Mark V tank, which was engineered to emit no visible smoke to avoid detection. By 1919, the firm established a laboratory at Shoreham-by-Sea and changed its name to Ricardo and Co.

In 1931, Harry Ricardo gave a lecture to the Royal Society of Arts in which he invited the audience to "accompany me inside the cylinder of a diesel engine," passionately describing the process of diesel combustion in great detail.

During the 1920s, the company developed the "turbulent head," a side-valve engine design that minimized clearance between the piston and cylinder head to achieve the performance of overhead-valve engines at a lower cost. This technology was patented in 1932. In the late 1920s, Ricardo designed a 130 brake horsepower six-cylinder diesel engine manufactured by AEC, which was utilized for London buses and long-distance lorries. This engine type, branded as The Comet, was subsequently adopted by European manufacturers including Citroën, Berliet, MAN, Fiat, and Breda.

In the 1930s, Ricardo expanded into high-performance and record-breaking machinery. The company converted a Kestrel V12 to diesel operation using single sleeve valve technology for Captain George Eyston. In May 1936, Eyston used this engine in the Flying Spray to set a world diesel speed record of 159 miles per hour at Bonneville. During this period, the company also developed a V-16 engine for the Alfa Romeo Tipo 162 and began work on what would become the Rolls-Royce Crecy engine following encouragement from Henry Tizard.

The firm’s involvement in jet propulsion began as early as 1940. For the Gloster E.28/39 jet aircraft, Ricardo developed the "Barostat" relief valve, which automatically reduced the pressure in the fuel lines as the aircraft gained altitude, thereby avoiding the risk of the engine overspeeding. Ricardo also assisted Frank Whittle with the design of fuel control systems and combustion chambers for his jet engine. Post-war projects included the development of an engine for the 4-8-4 Fell locomotive and a 1968 contract with the United States Navy for a "recycle diesel" unit capable of operating 600 feet underwater.

In the 1970s and 1980s, the company’s combustion-chamber technology was utilized by Opel for the 2100D engine in the Rekord Series D and by General Motors for the Chevrolet Suburban. In 1986, Ricardo redesigned the engine for the Rutan Voyager, the first aircraft to complete a non-refueled flight around the world.

In 1990, the company expanded its driveline operations, developing an automatic layshaft transmission and receiving a commission from Ferrari to create an automatic version of the 456GT. This was followed by the 1994 acquisition of FF Developments, which became the foundation for the company's UK driveline business.

In 2006, the firm’s combustion technology was used in the JCB Dieselmax, which Andy Green drove to a new diesel speed record of 350.092 miles per hour at Bonneville. In 2009, McLaren Automotive selected Ricardo to develop the 3.8-litre M838T engine for its supercar range. The company also improved the BMW K1200 series motorcycle engines, which were subsequently fitted to the K1300S, K1300GT, and K1300R models. In 2010, the company collaborated with Xtrac by assisting with some parts manufacture for the 1044 gearbox, supplied to the Lotus, Virgin, and HRT Formula One teams.

By 1990, the Shoreham-by-Sea facility housed over 90 test-beds, including anechoic chambers and rolling roads. These facilities enabled the company to develop engines of almost every type and size, from 5 hp chainsaw engines to 5,000 hp locomotive units. By 2017, the firm was engaged in the manufacture of gearboxes for Bugatti's street-legal production cars while continuing to produce engines for McLaren.

The firm diversified into environmental, rail, and defense sectors. In 2010, the Ministry of Defence selected the Ricardo-developed Foxhound vehicle to replace the Snatch Land Rover. The company acquired the consultancy firm AEA Technology in 2012, which was eventually rebranded as Ricardo Energy & Environment. In 2015, it acquired Lloyd's Register Rail to develop its rail expertise. Throughout the 2010s, the company also became active in the offshore wind turbine sector, providing engineering support for 7MW gearboxes. Following a recommendation by its board in June 2025, Ricardo was acquired by WSP Global in October 2025 for $670 million.