Jaguar V12 engine
Encyclopedia
Jaguar V12 piston engine was one of the premier powerplants of the 1970s and 1980s. It was first seen in the Series 3 Jaguar E-type of 1971 and was based loosely on an earlier design intended for a Le Mans
car, the ill-fated Jaguar XJ13
. The V12 was only Jaguar's second engine design to go into production in the history of the company. The all-alloy block was fitted with removable wet liners and had a SOHC 2-valve alloy head with flat combustion chambers.
. After its racing aspirations were put on hold in 1967, Jaguar considered the use of this quad-cam configuration for road use but it was judged to be too complex, large and heavy, as well as unacceptably noisy for a luxury car. The engine was extensively redesigned by Walter Hassan
and Claude Baily and the cylinder heads were replaced with more conventional 2-valve SOHC designs, reducing complexity, weight and noise. The revised head design had restrictive inlet ports which sacrificed top-end power but which, along with an increase in displacement to 5.3 litres, greatly improved performance at low-mid engine speeds, which was desirable in what was planned to be a heavy luxury car. The SOHC heads and the soft valve springs fitted to reduce valvetrain noise resulted in the redline being lowered to 6500 rpm from the 8000 of the original quad-cam design. When the limousine project was cancelled the engine was again left for a number of years before finally seeing production in the series III E-type in 1971.
OPUS electronic ignition. This system was used until 1982 when the Lucas CEI system was introduced. Initially the OPUS ignition amplifier unit was secured directly to the engine between the cylinder heads and had problems due to overheating. Later cars had the ignition amplifier moved away from the engine where it could get air flow for cooling. Originally the V12 was supposed to get an advanced Fuel Injection
system under development by AE Brico but this plan was cancelled at a late stage, possibly due to concerns that the design was too similar to Bosch products. The V12 as used in the Series 3 E-Types, Series 1 XJ12 and early Series 2 XJ12s (1973-April 1975) had four Zenith-Stromberg
side draft carburettors. After April 1975, the V12 engine used in the S2 XJ12 and the new XJ-S had a Lucas fuel injection system which was based around the Bosch D-Jetronic system.
This version was used in the following cars:
" cylinder heads, and had an unusually high compression ratio (10.5:1 – 12.5:1, depending on market and year). In any given market, power levels remained similar to the previous model, but fuel economy was improved by nearly 50%. The HE V12 engines had a fuel injection system from Lucas (dubbed Lucas Digital P) which was based on the Bosch D-Jetronic system.
The Lucas CEI ignition system continued until mid-1989, when it was superseded on the XJ-S by a system from Magneti Marelli. Series 3 XJ12 and Daimler Double Six cars used the Lucas CEI system until the end of production in 1992. The Marelli ignition system was used until the end of XJ-S production and on the 6.0 L V12 used in the XJ81 four-door saloons made in 1993–1994.
This engine cannot be tuned to the extent that previous versions were due to poorer gas flow. Another problem with the use of the May head design is that the chamber design creates a number of 'hot spots' under certain operating conditions that can cause runaway detonation and consequent engine failure. This was more of a problem with the 5.3 L version than the later 6.0 L derivative and affected a small number of vehicles in markets where sustained high-speed driving (well over 120 mph) was followed by a period of closed-throttle running. This failure mode was generally only seen in Germany where such conditions could be created on the Autobahn. This was actually due to the May design being significantly more efficient then the original flat-head design. That higher efficiency caused the .030-inch clearance between the piston and bore that was normally filled by the expansion of the hotter running piston to fill with carbon. The carbon would then come loose on heavy load/high rpm use (Autobahn) and cause "deposit induced detonation" or "wild ping", which would overheat the piston crown and cause the skirt to fail. All cars were fixed under warranty and no longer exists as a problem.
The 5.3 HE was used in these cars:
The 6.0 HE was used in the following cars:
became Jaguar's official team in World Endurance Championship, taking over the project from American team Group 44. Their first car, XJR6, used the 6.0 L engine, but in the following year the engine was upgraded to 6.9 L and in 1988 the XJR9 used the engine's most famous displacement of 7.0 L. By 1991, the V12 was good for 7.4 L inside the XJR12, developing an impressive 750 bhp
TWR also upgraded production Jaguar cars (usually XJ-Ss), with a variety of styling, handling and performance modifications. Most of the cars thus modified were straight from the Jaguar factory and sold through Jaguar dealerships.
By 1989, TWR were selling moderate numbers of XJ-Ss fitted with a 6.0 litre version of the V12, which pre-dated the Jaguar production version by some 3 years.
Lister Cars, a well-known Jaguar tuner with a long history of technical collaboration with the British automaker. The First Jaguar Lister XJS's were built by the company BLE Automotive in Erdington, Birmingham in the early 1980s until the Lister brand was passed on to WP Automotive of Leatherhead . In 1991, they fitted the 7.0 L (6996 cc/427 in³) version of the engine, with a 94 mm (3.7 in) bore and 84 mm (3.3 in) stroke, into a modified Jaguar XJS, which was rebadged Lister Le Mans. This engine officially produced 407.2 kW (546 hp) and 786.37 N·m (580 ft·lbf). From 1993, Lister Cars owner Laurence Pearce produced the company's first in house design the Lister Storm, which, naturally, continued using the V12 engine, both on the road and on the track, the car becoming a mainstay of the FIA GT Championship
and several national championships for the following decade.
24 Hours of Le Mans
The 24 Hours of Le Mans is the world's oldest sports car race in endurance racing, held annually since near the town of Le Mans, France. Commonly known as the Grand Prix of Endurance and Efficiency, race teams have to balance speed against the cars' ability to run for 24 hours without sustaining...
car, the ill-fated Jaguar XJ13
Jaguar XJ13
The Jaguar XJ13 was a prototype racing car developed by Jaguar to challenge at Le Mans in the mid-1960s.It never raced, and only one was ever produced...
. The V12 was only Jaguar's second engine design to go into production in the history of the company. The all-alloy block was fitted with removable wet liners and had a SOHC 2-valve alloy head with flat combustion chambers.
Development
Initial designs for the V12 were produced as early as 1954, with a view to using it in a Le Mans car. The engine was to be a 5.0 litre, quad-cam engine with a high redline. After Jaguar withdrew from racing, the V12 designs lay forgotten until the early 1960s when they were re-examined as a possible powerplant for a return to Le Mans with the Jaguar XJ13Jaguar XJ13
The Jaguar XJ13 was a prototype racing car developed by Jaguar to challenge at Le Mans in the mid-1960s.It never raced, and only one was ever produced...
. After its racing aspirations were put on hold in 1967, Jaguar considered the use of this quad-cam configuration for road use but it was judged to be too complex, large and heavy, as well as unacceptably noisy for a luxury car. The engine was extensively redesigned by Walter Hassan
Walter Hassan
Walter Hassan OBE, C.Eng., M.I. Mech.E. was a distinguished UK automotive engineer who took part in the design and development of three very successful engines: Jaguar XK, Coventry Climax and Jaguar V12 as well as the ERA racing car....
and Claude Baily and the cylinder heads were replaced with more conventional 2-valve SOHC designs, reducing complexity, weight and noise. The revised head design had restrictive inlet ports which sacrificed top-end power but which, along with an increase in displacement to 5.3 litres, greatly improved performance at low-mid engine speeds, which was desirable in what was planned to be a heavy luxury car. The SOHC heads and the soft valve springs fitted to reduce valvetrain noise resulted in the redline being lowered to 6500 rpm from the 8000 of the original quad-cam design. When the limousine project was cancelled the engine was again left for a number of years before finally seeing production in the series III E-type in 1971.
5.3 Litre
The 5.3 L (5343 cc) version had an oversquare 90 mm (3.5 in) bore and 70 mm (2.8 in) stroke. It produced 210 kW, (242 hp to 295 hp depending on emission controls and compression ratio) and 400 Nm (295 ft·lbf) in fuel-injected form. Right from the start of production in 1971 for the Series 3 E-Type, the V12 engine had LucasLucas Industries plc
Lucas Industries plc was a famous British manufacturer of components for the motor industry and aerospace industry. It was based in Birmingham. It was listed on the London Stock Exchange and was once a constituent of the FTSE 100 Index...
OPUS electronic ignition. This system was used until 1982 when the Lucas CEI system was introduced. Initially the OPUS ignition amplifier unit was secured directly to the engine between the cylinder heads and had problems due to overheating. Later cars had the ignition amplifier moved away from the engine where it could get air flow for cooling. Originally the V12 was supposed to get an advanced Fuel Injection
Fuel injection
Fuel injection is a system for admitting fuel into an internal combustion engine. It has become the primary fuel delivery system used in automotive petrol engines, having almost completely replaced carburetors in the late 1980s....
system under development by AE Brico but this plan was cancelled at a late stage, possibly due to concerns that the design was too similar to Bosch products. The V12 as used in the Series 3 E-Types, Series 1 XJ12 and early Series 2 XJ12s (1973-April 1975) had four Zenith-Stromberg
Zenith Carburetters
Zenith Carburetters was a British company making carburettors. In 1955 they joined with their major pre-war rival Solex Carburettors and over time the Zenith brand name fell into disuse...
side draft carburettors. After April 1975, the V12 engine used in the S2 XJ12 and the new XJ-S had a Lucas fuel injection system which was based around the Bosch D-Jetronic system.
This version was used in the following cars:
- Jaguar E-TypeJaguar E-typeThe Jaguar E-Type or XK-E is a British automobile, manufactured by Jaguar between 1961 and 1975. Its combination of good looks, high performance, and competitive pricing established the marque as an icon of 1960s motoring...
- 1975-1981 Jaguar XJSJaguar XJSThe Jaguar XJ-S is a luxury grand tourer produced by the British manufacturer Jaguar from 1975 to 1996. The XJ-S replaced the E-Type in September 1975, and was based on the XJ saloon. It had been developed as the XK-F, though it was very different in character from its predecessor...
- 1972-1981 Jaguar XJ12Jaguar XJJaguar XJ is the designation that has been used for a series of luxury saloon cars sold under the British Jaguar marque. The first XJ was launched in 1968 and the designation has been used for successive Jaguar flagship models since then. The original model was the last Jaguar saloon to have had...
(Series 1 and 2) - 1973-1981 Daimler Double-Six (Series 1 and 2)
- Panther J.72Panther J72The J.72 was the first product of the Panther Westwinds company, sold from 1972 through 1981. It was an ultra-exclusive luxury roadster, intended to compete with the best of the 1970s motor industry. It used mechanicals from the XJ12, including the 5.3 L Jaguar V12 engine, and was styled like...
- Panther De VillePanther De VilleThe Panther De Ville was a neo-classic luxury model from Panther Westwinds, the British specialty maker. Offered from 1974 to 1985, the De Ville was conceived by Robert Jankel to appeal to the taste of nouveau riche customers, including singer Elton John and actor Oliver Reed...
5.3-litre HE
A high-efficiency 5.3 HE version debuted in 1981. This used the special high-swirl design "MayMichael May (racing driver)
Michael May is a former racing driver from Switzerland. He participated in three Formula One World Championship Grands Prix, debuting on 14 May 1961...
" cylinder heads, and had an unusually high compression ratio (10.5:1 – 12.5:1, depending on market and year). In any given market, power levels remained similar to the previous model, but fuel economy was improved by nearly 50%. The HE V12 engines had a fuel injection system from Lucas (dubbed Lucas Digital P) which was based on the Bosch D-Jetronic system.
The Lucas CEI ignition system continued until mid-1989, when it was superseded on the XJ-S by a system from Magneti Marelli. Series 3 XJ12 and Daimler Double Six cars used the Lucas CEI system until the end of production in 1992. The Marelli ignition system was used until the end of XJ-S production and on the 6.0 L V12 used in the XJ81 four-door saloons made in 1993–1994.
This engine cannot be tuned to the extent that previous versions were due to poorer gas flow. Another problem with the use of the May head design is that the chamber design creates a number of 'hot spots' under certain operating conditions that can cause runaway detonation and consequent engine failure. This was more of a problem with the 5.3 L version than the later 6.0 L derivative and affected a small number of vehicles in markets where sustained high-speed driving (well over 120 mph) was followed by a period of closed-throttle running. This failure mode was generally only seen in Germany where such conditions could be created on the Autobahn. This was actually due to the May design being significantly more efficient then the original flat-head design. That higher efficiency caused the .030-inch clearance between the piston and bore that was normally filled by the expansion of the hotter running piston to fill with carbon. The carbon would then come loose on heavy load/high rpm use (Autobahn) and cause "deposit induced detonation" or "wild ping", which would overheat the piston crown and cause the skirt to fail. All cars were fixed under warranty and no longer exists as a problem.
The 5.3 HE was used in these cars:
- 1981-1992 Jaguar XJ12 (Series 3)
- 1981-1992 Jaguar XJS
- 1981-1992 Daimler Double-Six (Series 3)
6.0 Litre HE
The engine was stroked to 78.5 mm (3.1 in) in 1992 for a displacement of 6.0 L (5994 cc) to make this one of the most powerful Jaguar production engine to date at 318 hp. The 6.0 litre engine on X305 used a new Nippondenso distributorless crank-fired ignition system with coil packs very similar to Ford EDIS-6 units. The last Jaguar V12 engine was produced on April 17, 1997.The 6.0 HE was used in the following cars:
- 1992-1995 Jaguar XJS
- 1993-1995 Jaguar XJ12 (XJ81 and X305)
- 1993-1997 Daimler Double-Six (XJ81 and X305)
TWR/Lister
In 1985, Tom Walkinshaw RacingTom Walkinshaw Racing
Tom Walkinshaw Racing , was an auto racing team and engineering firm founded in 1976 by touring car racer Tom Walkinshaw.-History:TWR started by modifying BMW 3.0 CSLs, but soon was contracted to head Mazda's works program in the British Touring Car Championship. The TWR developed RX-7, with Win...
became Jaguar's official team in World Endurance Championship, taking over the project from American team Group 44. Their first car, XJR6, used the 6.0 L engine, but in the following year the engine was upgraded to 6.9 L and in 1988 the XJR9 used the engine's most famous displacement of 7.0 L. By 1991, the V12 was good for 7.4 L inside the XJR12, developing an impressive 750 bhp
TWR also upgraded production Jaguar cars (usually XJ-Ss), with a variety of styling, handling and performance modifications. Most of the cars thus modified were straight from the Jaguar factory and sold through Jaguar dealerships.
By 1989, TWR were selling moderate numbers of XJ-Ss fitted with a 6.0 litre version of the V12, which pre-dated the Jaguar production version by some 3 years.
Lister Cars, a well-known Jaguar tuner with a long history of technical collaboration with the British automaker. The First Jaguar Lister XJS's were built by the company BLE Automotive in Erdington, Birmingham in the early 1980s until the Lister brand was passed on to WP Automotive of Leatherhead . In 1991, they fitted the 7.0 L (6996 cc/427 in³) version of the engine, with a 94 mm (3.7 in) bore and 84 mm (3.3 in) stroke, into a modified Jaguar XJS, which was rebadged Lister Le Mans. This engine officially produced 407.2 kW (546 hp) and 786.37 N·m (580 ft·lbf). From 1993, Lister Cars owner Laurence Pearce produced the company's first in house design the Lister Storm, which, naturally, continued using the V12 engine, both on the road and on the track, the car becoming a mainstay of the FIA GT Championship
FIA GT Championship
The FIA GT Championship was a sports car racing series organized by the Stéphane Ratel Organisation at the behest of the Fédération Internationale de l'Automobile . The championship was mostly concentrated in Europe, but throughout the years has visited other continents including Asia and South...
and several national championships for the following decade.