Jaguar V12

In its first 20 years, Jaguar only produced two engines – the Jaguar XK and the Jaguar V12. I wrote about the many variants of the XK engine in a recent article and this is about the V12.

The first thoughts about a V12 engine came in the mid 1950s. Jaguar had gained great success at Le Mans with the C and D Types using the XK engine. They needed a larger, more powerful motor and designed a quad cam V12 of about 4.5 litres. As it was designed for racing it had a high redline. Jaguar didn’t put the engine into any form of production as they withdrew from racing after winning the Le Mans 24-hour race 3 times in 1955, 56 and 57 – they had also won in 1951 and 1953. The engine design was dormant for several years before two things happened.
1. Jaguar wanted to go after Ferrari and Ford in sports car racing.
2. They also wanted to develop a luxury car to complete the range.

So they revisited the V12. For sports car racing they had developed a prototype, the Jaguar XJ13 with the V12, now a 5 litre with aluminium heads off the XK engine. It produced 430hp although the engineers managed to tune it to 500. Ultimately the XJ13 was also stillborn – only one was built (and never raced) because Ford and Lola had built the GT40 with a 7-litre motor that dominated sports car racing during the late 1960s.

The second reason for bringing the V12 out of the design bin was for a luxury saloon and for the Series 3 E Type. The Series 1 and 2 E Types had the 3.8 and 4.2 litre XK engines and the Series 3 had a road going version of the V12. It was increased to 5.3 litres and the heavy and complex quad cam setup was dropped in favour of 2 valve heads with a single overhead cam on each block. Power was down to 285 horses straight from the factory. The Series 3 E Type was in production from 1971 to 1975.

Jaguar also slotted the engine into the XJ12 Series 1 and 2 from 1972 onwards. It was also in the Daimler variant, the Double Six and the E Type’s successor, the XJS. Originally the engine used four Zenith Stromberg carbs and later versions used Lucas fuel injection. The motor was also used in the Panther J72 (a Jaguar SS100 clone) and the Panther De Ville, a “neo classic” luxury car.

In 1981 the 5.3 was uprated to the 5.3 HE for High Efficiency. Power was the same as the old engine but fuel economy was 50% better. The engines had new heads called High Swirl with higher compression and they were in production for 11 years. Like the earlier version, they had Lucas ignition systems although the XJS used a Magneti Marelli system. The final road version that was in production for four years from 1992, was a 6-litre version of the HE engine. It was increased by stroking the engine by a further 8mm.

Jaguar’s last two Le Mans wins of 1988 and 1990 with Tom Walkinshaw Racing’s XJR9 and XJR12 used a 7-litre version of the V12 producing 730hp. These cars also took the World Sportscar Championship three times.