The Evolution of Jaguar’s XK Six-Cylinder: An Iconic Engine Produced for 43 Years – autoevolution
The origins of the British marque date back to 1922, when two motorcycle enthusiasts, William Lyons and William Walmsley founded the Swallow Sidecar Company. In the following years, they started developing bodies for passenger cars in addition to motorcycle sidecars, and by 1935, the business, renamed S.S. Cars, introduced the first in-house developed sedan. In 1936 a two-seat sports car named S.S. Jaguar 100 hit the streets, but as the Second World War started three years later, vehicle manufacturing ceased, and the S.S. moniker took on a far more sinister connotation. This lead to a rebranding of the company which became Jaguar Cars in 1945.
During the second global conflict, work at the Foleshill factory in Coventry revolved around repairs of Whitley bombers and manufacturing sidecars or trailers for the armed forces, but chairman William Lyons didn’t give up on his original business. In absolute secrecy, he tasked the engineering team led by Bill Heynes with developing a new series of engines that would help revive the company after the war concluded.
As the British Isles were being bombarded by Nazi forces, Heynes along with his fellow engineers Walter Hassan and Claude Baily were assigned fire-watching duties. It was during these long hours spent on the factory’s roof where the groundwork for the XK engines was laid out.
As soon as the war ended and the company was rebranded, the engineering team began refining two prototype units that they had covertly built during the last two years.
One was a four-cylinder intended for smaller-sized sedans, while the other was a six-cylinder that would serve as Jaguar’s flagship engine. The latter showed more promise and it benefitted from the bulk of the development work in the years that followed.
The aim was to create a powerplant that could be not only reliable, but also powerful enough for a sporty sedan that could achieve a top speed of 100 mph (161 kph). To achieve this, the engineers employed innovative design features such as hemispherical combustion chambers or dual overhead camshafts (DOHC), a layout that was rarely used on mass-produced engines at the time.
On 15th September 1947, an advanced production candidate of the novel XJ six-cylinder was fired up for the first time. Built on a cast-iron block with a lightweight aluminum head, it had a bore and stroke of 83 x 98 mm (3.26 x 3.85 in.), displaced 3.2 liters (195 ci.), and produced 142 hp at 5,000 rpm. This wasn’t a major increase over the Standard Motor Company-build inline-six used by the company in the prior decade, so the stroke was lengthened to 106 mm (4.17 in.). This increased the volume to 3.4 liters (210 ci), while the output went up to 160 hp at 5,000 rpm.
Jaguar now had the powerful, smooth-running engine that they had envisioned, but the sports sedan it was intended for was far from finished. For the 1948 London Motor Show – which started a little over a month after the final form of the engine was ready – the manufacturer surprised everyone when it …….