The company's origins lie in a 1903 joint venture called Lee Stroyer, founded by Jens Stroyer and Horace Pelham Lee, a former Daimler employee. In 1905, following Stroyer's departure, the business relocated to Paynes Lane, Coventry, and was renamed Coventry Simplex. Its engines powered early GWK cars and, just before the First World War, were used by Lionel Martin to power the first Aston Martin car. Ernest Shackleton also selected Coventry-Simplex engines for the tractors intended for his 1914 Imperial Trans-Antarctic Expedition.
In 1919, Pelham Lee acquired another business and established Coventry Climax Engines Ltd at East Street, Coventry. Throughout the 1920s and 1930s the company supplied engines to a broad range of light-car manufacturers including Morgan, Triumph, Standard, and Clyno. It also developed commercial vehicle engines and, crucially, diversified into mobile fire pump units — a direction that would unexpectedly open the door to motor racing.
In 1950, Harry Mundy joined the company and, working with chief engineer Walter Hassan, developed a new lightweight all-aluminium overhead-camshaft engine in response to a government requisition for a portable fire pump capable of pumping double the required water volume at half the previous weight. Designated the FW (Featherweight), the engine weighed just 180 pounds in its base form.
When the FW was displayed at the London Motor Show, it attracted immediate attention from the racing community. Cyril Kieft and the young Colin Chapman both approached Coventry Climax, arguing that racing success would bring the company commercial publicity. The management agreed, and the FWA — Featherweight for Automobiles — variant was developed from the 1,020cc pump engine as a 1,098cc racing unit producing 71 bhp at 6,000 rpm. It made its competition debut at the 1954 24 Hours of Le Mans in a Kieft sports car.
The FWA was followed by the larger FWB of 1,460cc, which suited the 1.5-litre Formula Two regulations of the early 1950s and quickly became the preferred choice for F2 competitors. By 1957, Climax engines had migrated to Formula One, initially in Cooper chassis.
The double-overhead-cam FPF four-cylinder was the engine that elevated Coventry Climax to the pinnacle of Grand Prix racing. Designed as a pure racing unit from the outset, it first appeared in 1.475-litre Formula Two form in 1956 before being progressively enlarged for 2.5-litre Formula One use. Stirling Moss scored the company's first Formula One victory in Argentina in 1958 using a 1,964cc version in a Cooper. As the engine reached 2,497cc by 1960, Jack Brabham won back-to-back World Championships of Drivers in 1959 and 1960 in Cooper-Climax machinery.
A 2,751cc variant of the FPF was also built for the Indianapolis 500 and contested in the Intercontinental Formula, while smaller versions were adapted for the 1.5-litre Formula One regulations introduced in 1961, winning three championship races that year.
The FWE, a 1,216cc variant of the FW series designed specifically for the Lotus Elite under a 1,000-unit purchase agreement with Colin Chapman, also proved exceptionally successful in sports car racing: FWE-powered Lotus Elites won their class six times at the 24 Hours of Le Mans and also took the Index of Thermal Efficiency.
For the new 1.5-litre Formula One of 1961, Coventry Climax developed the FWMV — a 1,496cc V8 derived from the smaller FWMC four-cylinder. Designed by Hassan and Mundy (with Peter Windsor Smith taking an increasing role from 1960), the FWMV debuted at the 1961 German Grand Prix. After early overheating problems were traced to differential thermal expansion between steel cylinder liners and aluminium components and subsequently cured, the engine became extremely competitive.
In its Mk.III form for 1963, fitted with Lucas fuel injection and switching to a flat-plane crankshaft, the FWMV produced 195 bhp at 9,500 rpm. Jim Clark used this engine in the Lotus 25 to win seven championship races, seven pole positions, and the 1963 World Championship. The Mk.4 version produced 200 bhp at 9,750 rpm for 1964, with Clark winning three more races that season; the further developed Mk.6 with four-valve cylinder heads produced 212 bhp at 10,300 rpm. Clark won a second World Championship in 1965 with FWMV power. In total, FWMV-powered cars from Cooper, Lotus, and Brabham won 22 World Championship Grands Prix.
The FWMV also proved significant in engine design history: the Mk.III demonstrated that a flat-plane crankshaft was more advantageous for a racing V8 than the conventional crossplane arrangement, contradicting the prevailing engineering consensus. Flat-plane V8 crankshafts became standard in racing engine design from the 1970s onward.
Coventry Climax attempted to develop a 1.5-litre flat-16 engine, the FWMW, to succeed the V8, but the project was beset by destructive torsional vibration in the crankshaft and was ultimately abandoned. When the Formula One regulations changed to three litres for 1966, the company announced it could not build a competitive new engine and withdrew from Grand Prix racing.
The company was purchased by Jaguar Cars in 1963, and the engineering team — Hassan, Mundy, and others — subsequently designed the Jaguar V12 engine that entered production in 1971 and remained in service until 1997. Jaguar itself merged with the British Motor Corporation in 1966 to form British Motor Holdings, which in turn merged with Leyland Motor Corporation in 1968. Coventry Climax became part of British Leyland and, following further corporate restructuring, the forklift truck business was sold back into private ownership in 1982. The company went into receivership in 1986.
In May 1964, the Royal Automobile Club awarded Coventry Climax the Dewar Trophy — the most prestigious award in British automotive engineering — for the design, development, and production of engines that had brought British cars to the forefront of Grand Prix racing. The citation specifically recognized the achievement of supplying engines that carried British constructors to the World Championship.
The last victory for a Climax-powered car in an international event was Mike Spence's win in the non-championship 1966 South African Grand Prix, driving a Lotus 33. Climax-powered cars made their final World Championship Grand Prix entries at the 1969 Canadian Grand Prix, a full three years after the company's official withdrawal from Formula One.