V12 engine development
Then, as now, Jaguar's biggest export market was the USA. By 1971 pressure was mounting for manufacturers to reduce the emissions from their engines. Although the necessary reductions could have been achieved on the long serving XK six-cylinder engine that had been fitted to the E-Type since its introduction, this would have greatly reduced its performance.
So a new engine was needed that would meet the new American regulations but still deliver the 'punch in the back' that E-Type owners expected. The question was, what type of engine should it be? Over the years Jaguar had built a reputation for engineering innovation and this was to be a significant factor in designing the new engine. When the XK engine had been introduced in 1948, it was one of the few double overhead camshaft straight six engines available to the public.
The image of technical superiority was important to Jaguar. A V8 configuration was considered but discarded as being too common, especially in the USA where Jaguar had a big market for the E-Type. For the E-Type to retain its unique appeal, something out of the ordinary had to be developed.
The prestigious Ferrari and Lamborghini cars had created something of a mystique about V12's in both Europe and the USA, so the logical step was to consider a V12 configuration. There were several advantages to this type of power unit including the fact that a V12 is significantly smoother than a V8. So the V12 became the preferred engine design for the revised E-Type. In fact, Jaguar had been working on a V12 (quad overhead cam) for some years. It had been intended for the company's return to racing when fitted to the experimental XJ13 racing car, although factory sponsored Jaguars were not to be seen on the racing track till many years later.
Unfortunately, the engine that had been designed for racing proved to be too complex and expensive for a production engine, added to which the dual overhead cams per bank made it too big for the E-Type. Nevertheless, it was this unit that was to provide the basis of the 5.3 litre V12 unit (single overhead cam per bank) that was eventually fitted to the new E-Type.
Renowned engine designers (including racing engines) Walter Hassan and Harry Mundy applied their magic and developed the production V12 with a lightweight alloy block and heads. The narrow 60 degree V design enabled the twelve cylinder marvel to fit inside the narrow subframes of the E-Type. A number of small single cylinder test engines were built to test cylinder head and combustion chamber designs. Remember that this was before the introduction of sophisticated computers and CAD drawing programs that are now used for such design exercises.
The tests resulted in the surfaces of the V12 aluminium heads being machined flat and the combustion chambers placed inside the piston crowns. This design provided more efficient combustion, improved mid range power, helped to satisfy the anti-pollution requirements and also made for easier (and cheaper) manufacture.
Industry leading electronic ignition, four Zenith Stromberg carburettors and a free flowing exhaust system completed the revolutionary new engine package from Jaguar. This basic engine design was used to power Jaguars for another twenty five years until it was finally retired in 1995 with a six litre capacity.