50 years of the Jaguar V12 engine

Terrific 12

The engine we all know as the Jaguar V12 was officially called the XJ6, which is slightly confusing because it was never fitted to a car of that name.

It was only Jaguar’s second engine designed for road use, following the six-cylinder XK of 1948 and preceding the AJ6 of 1983.

Although Jaguar had experimented with a V12 design during the early ’50s, it was not until 1971 that the engine became a production reality. And after all that work, it remained in production, with modifications, for over a quarter of a century until 1997. Here is its story.

Jaguar XJ13

Jaguar started thinking about creating a V12 in the 1950s, but did not get round to putting one in a car until 1966.

The car in question was the XJ13, a mid-engined sports racer of surpassing beauty which was unfortunately abandoned before taking part in any competition.

The 5.0-litre engine, with four camshafts mounted in two cylinder heads, was not closely related to the later production V12.

However, as the first Jaguar ever fitted with an engine of this configuration, the XJ13 undoubtedly deserves a place in this gallery.

Jaguar E-type

The production V12 was simpler than the one in the XJ13, with just two camshafts, but slightly larger at 5.3 litres.

Reportedly, its debut in the 1971 E-type was due to management caution. The XJ was another option, but fitting Jaguar’s first new engine in 23 years to a relatively high-volume saloon car was considered too risky.

The new model was quick, though not as quick as Jaguar said it was; claims of a 150mph top speed could not be independently verified.

Furthermore, contemporary reviewers complained that the steering was inferior to that of six-cylinder E-types.

Jaguar XJ12

The V12 made its next appearance in a car Jaguar had been selling since 1968.

This was the very popular XJ6 saloon. As mentioned previously, the engine was also known internally as XJ6, but when the two came together the car was named XJ12.

The combination seemed very effective for about a year. Then came the global oil crisis of 1973, which made the XJ12’s heavy fuel consumption more of a problem than it had been previously.

Panther J72

The first car produced by British manufacturer Panther was the J72. Its styling was based on that of the pre-war SS100, which appeared in the days when what we now know as Jaguar was still called SS Cars.

The connection was strengthened by the fact that the J72 was only ever supplied with Jaguar engines.

These included two versions of the six-cylinder XK in 3.8- and 4.2-litre forms, but the 5.3-litre V12 was available to wealthier customers.

Daimler Double Six

The Daimler Sovereign was the companion vehicle to the Jaguar XJ6, launched a year later in 1969.

Converting the car to take the V12 engine was exactly the same process as doing the same thing to the XJ6.

As with the Jaguar, it also led to a name change. For the 12-cylinder Sovereign, Daimler brought back the Double Six name it had first used in the mid 1920s.
 

Panther De Ville

The De Ville was an altogether more extravagant machine than Panther’s earlier J72.

The inspiration this time was the awe-inspiring Bugatti Royale. Understandably, Panther was unable to come even halfway towards providing an engine to match the Royale’s monumental 12.7-litre straight-eight.

Instead, the company once more offered Jaguar engines, namely the 4.2-litre XK and the 5.3-litre V12.

Jaguar XJ-S

Although its styling was considered controversial in the early days, the XJ-S (initially with a hyphen in its name) remained in production for more than two decades, from 1975 to 1996.

It was the first Jaguar designed from scratch to be fitted with the V12 engine. A six-cylinder model, powered by the new AJ6 unit, would not appear until 1983.

Jaguar XJ12 HE

In 1981, Jaguar adopted a new cylinder head design for the V12. Invented by Swiss engineer and former racing driver Michael May, it was known as Fireball.

Despite this dramatic name, the head’s combustion chamber in fact allowed similar power to be achieved using less fuel – hence the letters HE, which stood for High Efficiency.

This was an important development for the notoriously thirsty XJ12 (and its companion model, the Daimler Double Six), which became slightly cheaper to run as a result.

Jaguar XJ-S HE

The HE version of the V12 also made a difference to the XJ-S, helping it to become more popular than it had been in its first six years.

Petrol still gushed into the engine at a tremendous rate, but achieving 20mpg on a journey was now a realistic ambition.

Lister Le Mans

The Le Mans was the first model produced by the new Lister company in 1986.

Every one of the approximately 90 examples started out as a Jaguar XJ-S, but there were many modifications.

These included raising the capacity of the V12 engine to 6.0 litres. Along with changes to the cylinder heads, fuel injection and management system, among other things, this raised the power output to a quoted 482bhp.

Jaguar XJR-S

The XJR-S was a derivative of the XJ-S developed by JaguarSport, a joint venture created by Jaguar itself and Tom Walkinshaw Racing.

It made its debut in 1988, fitted with uprated suspension but retaining the 5.3-litre V12 HE engine.

For the 1991 version, the engine was modified in several ways, including an enlargement to 6.0 litres. Its power output accordingly rose to 333bhp.
 

Jaguar XJR-15

The very limited-production XJR-15 was based on the XJR-9 sports racer.

It was powered by a 6.0-litre version of the V12 engine producing 450bhp.

Although it was developed by JaguarSport as a road car (startlingly priced at £500,000), the XJR-15 is best known for being the car used in the one-make 1991 Jaguar Intercontinental Challenge race series, which took place over three rounds at Monaco, Silverstone and Spa-Francorchamps.

Jaguar XJS 6.0 HE

6.0 litres became the standard capacity of the V12 in the early 1990s.

In the case of Jaguar’s sports coupé and convertible, the switch occurred at about the same time as a facelift and a slight name change to now the unhyphenated XJS.

Jaguar had also been taken over by Ford, and was now part of the larger company’s Premier Automotive Group.
 

Jaguar XJ12 6.0 HE

The 1986-1994 XJ, codenamed XJ40, was offered only with a six-cylinder engine for much of its production life.

The 6.0 V12 HE XJ40 was not introduced until 1993, but it was carried over to the next-generation XJ12 and Daimler Double Six.

Jaguar’s last-ever production V12 was an XJ built on 17 April 1997. The engine was replaced by the eight-cylinder AJ-V8, which was available in many capacities, and with or without supercharging.

Lister Storm

The V12 could be taken out to 7.0 litres, but it never appeared in that size in any production Jaguar.

This was, however, the capacity chosen for the Lister Storm. This 546bhp monster is best known as a racing car, but there was also a roadgoing version.

Due to its very high price, Lister built only four examples before concentrating its efforts on the racers.

Jaguar XJ220 concept

Like the XJ13 built more than 20 years earlier, the XJ220 concept of 1988 had a mid-mounted V12 engine.

In the later car, it measured 6.2 litres and drove all four wheels.

By the time the XJ220 went on sale in 1991, nearly all of the above had changed. The engine was still located behind the passengers, but it was a turbocharged V6 (related to the unit used in the Metro 6R4 rally car) driving only the rear wheels.

Racing E-types

Most of the best-known E-type racers were powered by the six-cylinder engine.

However, towards the end of production, the Group 44 and Huffaker teams raced V12 E-types in SCCA (Sports Car Club of America) events with great success.

The discontinuation of the model in 1975 brought these projects to an end, but they had done a fine job of promoting Jaguar in the US.

Broadspeed XJ12C

British company Broadspeed prepared the two-door XJ12C for racing in the European Touring Car Championship in the mid 1970s.

Although it looked and sounded fabulous, the car was not as competitive as had been expected.

With more development time, it could have been a contender, but the project was abandoned after two seasons.

Group 44 XJ-S

Group 44 followed its E-type campaign by converting the XJ-S V12 for Trans Am racing.

Team boss Bob Tullius won Category 1 of the series in both 1977 and 1978. Jaguar was champion manufacturer in the latter year.

TWR XJ-S

Tom Walkinshaw Racing’s XJ-S was more standard-looking than the Group 44 version, but it was still a very highly developed racer.

Walkinshaw himself won the European Touring Car Championship with the V12 Jaguar in 1984.

One year later, TWR achieved Jaguar’s first – and so far only – victory in one of Australia’s most famous motorsport events, the Bathurst 1000 touring car race.

Jaguar XJR-12

Both Group 44 and TWR created purpose-built, but Jaguar V12-powered, cars for international sports car racing.

The XJR series began with Group 44’s 1983 XJR-5. Seven years later, TWR won the Le Mans 24 Hour race with the XJR-12.

This was not the final XJR, but it was the last to be powered by the V12, now measuring 7.0 litres. Its successor, the XJR-14, used a 3.5-litre Cosworth HB V8 engine.