The XK engine powered the golden age of Jaguar sports cars

During the wartime years, Jaguar founder William Lyons began planning his next challenge: a new 100mph (160kph) saloon for the next post-war era.

The result was the XK engine. Launched at Earls Court in 1948 and arguably the most significant event in Jaguar’s history. Over the next 38 years, the XK engine would power five Le Mans winners, big prestige saloons, compact saloons, later XKs, the XK-E, executive saloons of the 70s and 80s, military vehicles, fire engines and record-breaking power boats.

The XK engine was first used to power the XK120 sports car. Inspired by the BMW 328 sports car, the car’s success took Jaguar by surprise, particularly in America. Three XK120s were entered into the 1950 Le Mans 24-hour race. Two of them finished 12th and 15th, and although the third dropped out, it had been in 3rd place, convincing Lyons that “in a car more suitable for the race, the XK engine could win this event”.

The XK120 was produced as a road-going car until 1954 when it was replaced by the XK140, although the XK140 sold less well.

The ‘more suitable’ race car needed to be faster, lighter, more powerful than the XK120 with a new, aerodynamically improved body. The result – the C-type, designed by William Heynes and Malcolm Sayer. Heynes modified the chassis and rear structure, and introduced rack and pinion steering gear. The XK120 engine was also modified. Sayer’s brief was to design an aerodynamically more efficient body while still being identifiably related to the XK120. In the 1953 Le Mans race, the C-types came in 1st, 2nd and 4th.

Attempting to reduce weight further, Heynes developed a new model using a new monocoque construction technique, whereby the chassis is integral with the body. The resulting new model was impressive, but the team were convinced that if Jaguar was to maintain its success at Le Mans, a completely new car, with further reduced weight, greater engine power and improved aerodynamics, would be needed.

The D-type was engineered with a completely new framework, small modifications were made to the C-type engine and its bodywork was redesigned, this time influenced by the 1952 Alfa Romeo Touring-bodied Disco Volante, and using Sayer’s unique mathematical methodology. In the 1954 Le Mans, two D-types dropped out, and the third came in 2nd, 2 minutes behind Ferrari.

The D-type performed well between 1955 and 1960 at Le Mans. Since 1951, a Jaguar had won Le Mans on five occasions: a British record only rivalled by Bentley in the 1920s. It made Jaguar a famous name, particularly in America. Despite this success, the Production D-types did not sell well.

In 1955 Jaguar introduced a new medium-sized car, powered by a 2.4-litre XK engine, the first Jaguar to be produced in quantity. In 1960, an improved Mark II form was produced, selling until 1968.

For 1956, Jaguar finished racing. Work started on a replacement for the XK150. It finally made its appearance in March 1961 – the XK-E.

The XK-E’s length was longer than the D-type. Although its structure was based on the D-type, and it had a 2.4-litre XK engine. It is believed that the XK-E was originally intended for both ‘production car’ and ‘racing’.

Reports from the time confirm that “whilst the basic shape was undoubtedly Sayer’s, never the less, the master stylist, Lyons, had a hand in finalizing important details”.

In 1958, editor of Motor Weekly had the opportunity to test drive the early XK-E (known as E1A) who concluded “…the new Jaguar is a potential world beater…”.

1960 – A pure competition version of the XK-E was produced: a Sports racer which would have succeeded the D-type, known as E2A . Bigger than its predecessor with a new independent rear-suspension system. Also fitted with a special 3-litre XK engine, E2A entered into the 1960 Le Mans by Briggs Cunningham.

By late 1960, XK150 sales continued to fall and a new model became increasingly urgent.

By the early 1960s, the urban population had become younger and more affluent. Music, fashion and design flourished. Men and women flocked to Carnaby Street and the King’s Rd in London where Mary Quant’s mini-skirts were flying off the rails. The time was ripe for an equally sensational new sports car and in 1961 the XK-E made its debut at the Geneva Motor Show: a race-bred, visually sensational sports car selling for half the price of its competition models.

The show car was unveiled in a restaurant – the Parc des Eaux-Vives – to a gasp by the world press…