Jaguar XK Engine

With a brief from Sir William Lyons to produce an engine that would stay ahead of the opposition and also had to “look good”, William Heynes (Chief Engineer), Claude Bailey, Walter Hassan and Harry Weslake began work in 1944 on development engines that would, by September 1947, become a 3.2-litre six-cylinder engine in the format of the XK engine we now know. A last-minute change to a longer stroke, to increase torque, gave 3,442 cc and saw the XK’s introduction at the 1948 London Motor Show in the XK120 sports car.

Throughout its production life the engine had various displacements for road-going versions: starting with a 2.4-litre (used in the “bank manager’s special” MK2 and in the 240), a 2.8-litre (an option for XJs from 1968 to 1974), a 3.4-litre, a 3.8-litre and a 4.2-litre. A special 3-litre version was also developed, used exclusively in motorsport.

During this period the engine was used in just about every road car produced by Jaguar, and also found its way into Scorpion tanks, Scimitar armoured reconnaissance vehicles, and a Dennis fire engine.

During the remarkable production run of 44 years, changes were made throughout the engine’s life. Six different cylinder heads were developed and used — with changes to porting, valve angles and valve sizes — block castings changed, and various carburettors and fuel injection systems were employed across the range.

The ultimate Jaguar XK engine was the race-derived 3.8-litre unit: aluminium block, wide-angle cylinder head, dry-sump lubrication and fuel injection, as fitted to only a handful of Jaguar Lightweight E-Types.