V12 engine

A V12 engine is a twelve-cylinder piston engine where two banks of six cylinders are arranged in a V configuration around a common crankshaft.

Many, but not all, V12 engines use a V-angle of 60 degrees between the two banks of cylinders. Because of the balanced nature of the engine, and the smooth delivery of power, these engines were popular in early luxury automobiles, boats, and aircraft. The powerful V12 engines used in aircraft of the Second World War were later displaced by jet turbine engines. The V12 configuration fits well in longer vehicles such as locomotives or heavy trucks. Compared to internal combustion engines with fewer cylinders and similar power ratings, a V12 will have more moving parts, a more complex exhaust system, and will be more expensive to manufacture. V12 engines are rarely found in modern luxury automobiles or highway trucks, but are still used in stationary engines, ships, locomotives, and military vehicles.

Design

Balance and smoothness 
Each bank of a V12 engine essentially functions as a straight-six engine, which by itself has perfect primary and secondary engine balance. By using the correct V-angle, a V12 engine can therefore have perfect balance. The even firing order for a four-stroke V12 engine has an interval of 60 degrees, therefore a V12 engine can be perfectly balanced if a V-angle of 60 degrees, 120 degrees or 180 degrees is used. V12 engines with other V-angles have been produced, sometimes using split crankpins to reduce the unbalanced vibrations. The drawback of a V12 engine is the extra cost, complexity and friction losses compared with engines containing fewer cylinders.

At any given time, three of the cylinders in a V12 engine are in their power stroke, which increases the smoothness of the power delivery by eliminating gaps between power pulses.

A V12 engine with a 180 degree V-angle is often called a flat-twelve engine (or a 'boxer twelve'), however this terminology is incorrect for the majority of 180-degree V12 engines, since they use shared crankpins and are therefore not configured as flat engines.

Theoretically, the rotating parts of a V12 racing engine could be lighter than a crossplane V8 engine of similar displacement, due to the V12 engine not requiring counterweights on the crankshaft or as much inertial mass for the flywheel. In addition, the exhaust system of a V12 engine is much simpler than would be required for a crossplane V8 engine to achieve pulsed exhaust gas tuning. However, use of V12 engines in motor racing is uncommon in the 21st century.

Size and displacement 
A 60-degree V12 engine is typically narrower than a 90-degree V6 or V8 engine of similar displacement. However, the V12 engine is usually longer than V6 and V8 engines. The added length often makes it difficult to fit a V12 engine into a passenger car, however the length is not typically a problem for trucks engines and stationary engines. Due to its narrower width, the V12 is common in locomotive, armoured tank and marine engines. In these applications, the width of the engine is constrained by tight railway clearances or street widths, while the length of the vehicle is more flexible.

In twin-propeller boats, two V12 engines can be narrow enough to sit side-by-side, while three V12 engines are sometimes used in high-speed three-propeller configurations. Large, fast cruise ships can have six or more V12 engines. In historic piston-engine fighter and bomber aircraft, the long, narrow V12 configuration used in high-performance aircraft made them more streamlined than other engines, particularly the short, wide radial engine.

Usage in marine vessels 

The first V-engine (a V-twin design) was built by Daimler in 1889, then the first V8 engine was built by Antoinette in 1903. These were followed by the first V12 engine in 1904, which was built by Putney Motor Works in London for use in racing boats. Known as the "Craig-Dörwald" engine after Putney's founding partners, the V12 engine was based on Putney's existing two-cylinder engine with a flathead design, a V-angle of 90 degrees and an aluminium crankcase. As in many marine engines, the camshaft could be slid longitudinally to engage a second set of cams, giving valve timing that reversed the engine's rotation to achieve astern propulsion. The engine had a displacement of  a weight of  and developed . The engine was intended for use in 40-foot hull racing boats, however little is known of its racing achievements.

Two more V12s appeared in the 1909-1910 motor boat racing season. The Lamb Boat & Engine Company in the United States built a  engine for the company's 32-foot 'Lamb IV' boat. The Orleans Motor Company built a massive  flathead V12 engine with a power output quoted as "nearly ".
In 1914, Panhard built two  V12 engines with four valves per cylinder, which were designed for use in racing boats.

Usage in airplanes

1900s to 1930s 

Five years after the first V12 engine was introduced, Renault introduced the first V12 engine for aircraft in 1909. This engine had a V-angle of 60 degrees, air cooling and an intake over exhaust (F-head) valve arrangement. It had a displacement of , a weight of  and produced  at 1,800 rpm. The propeller was driven from the front end of the camshaft, thus spinning the propellor speed at half the speed of a typical crankshaft driven propellor, in order to improve the propellor efficiency. The Renault engine was closely mimicked by the RAF 4 and its derivatives, which was used by various British military aircraft during World War I. The RAF 4 engine had a displacement of , weighed  and produced produced  at 1,800 rpm.

In March 1914, a prototype version of the Sunbeam Mohawk V12 engine was unveiled in the United Kingdom, based on the 'Toodles V' motor racing engine. The production version was rated at  at 2,000 rpm, making it the most powerful airplane engine in Great Britain at the outbreak of World War I. During and after World War I, various companies in the United States produced the Liberty L-12 engine. In Austria, the Austro Daimler V12 engines were used by the large flying boats of the Naval Air Force and produced up to . By the end of World War I, V12s were well established in aviation, powering some of the newest and largest fighter and bomber airplanes.

After World War I, many Zeppelins used V12 engines built by Maybach and Daimler. V12 engines powered the first transatlantic crossings by the Curtiss NC flying boats (using four Liberty L-12 engines), the first non-stop transatlantic crossing in a Vickers Vimy (using two Rolls-Royce Eagle engines) and the first transatlantic crossing by an airship in the R-34 class airship (using five Sunbeam Maori engines).

1940s to present 

V12 engines reached their apogee during World War II with engines such as the British Rolls-Royce Merlin and Rolls-Royce Griffon, the Soviet Klimov VK-107 and Mikulin AM-38, the American Allison V-1710, and the German Daimler-Benz DB 600 and Junkers Jumo. These engines generated about  at the beginning of the war and over  at their ultimate evolution stage. This rapid increase in power outputs was due to technology such as multi-speed superchargers and high octane fuels, and the V12 layout was commonly adopted due to its low vibrations so that the powerful engines did not tear apart the light airframes of fighters.  

The Allied forces used V12 engines with an "upright" design, however many German engines (aside from the BMW VI, which was designed prior to World War II) used an inverted engine design, which had a lower centre of gravity and improved pilot visibility for single-engined designs. The only American-design inverted V12 engine of any type to see even limited service in World War II was the air-cooled Ranger V-770, which was used in aircraft that were only used for training purposes within the United States, such as the Fairchild AT-21 Gunner.

The Rolls-Royce Merlin V12 engine was used in several British aircraft including the Hawker Hurricane and Supermarine Spitfire fighters, and the Avro Lancaster and de Havilland Mosquito bombers. The Hurricane and Spitfire playing a vital role in the Battle of Britain. The long, narrow configuration of the V12 contributed to good aerodynamics, while its smoothness allowed its use with relatively light and fragile airframes. The Merlin was also used in the .

In the United States, the Rolls-Royce Merlin engine was produced under licence as the Packard V-1650, which was used in the P-51 Mustang fighter. This engine was also incorporated into some models of the Curtiss P-40, specifically the P-40F and P-40L. Packard Merlins powered Canadian-built Hurricane, Lancaster, and Mosquito aircraft, as well as the UK-built Spitfire Mark XVI, which was otherwise the same as the Mark IX with its British-built Merlin. The Allison V-1710 was the liquid-cooled V12 engine designed in the United States that was used on active service during World War II. It was initially used in the P-38 Lightning, however the turbosupercharger system required bulky ductwork and had poor high-altitude performance. In 1943, a version using a more conventional mechanical supercharger began production.

After World War II, V12 engines became generally obsolete in aircraft due to the introduction of turbojet and turboprop engines that had more power for their weight, and fewer complications.

Usage in automobiles 
In automobiles, V12 engines are less common than engines with fewer cylinders, due to their size, complexity and cost. They have been mostly used in expensive sports and luxury cars thanks to their power, smooth operation and distinctive sound.

1910s 

One of the earliest recorded uses of V12 engines in automobiles was in October 1913, when a custom-built racing car competed at the Brooklands circuit in the United Kingdom. The car was entered by Louis Coatalen, who was chief engineer of the Sunbeam Motor Car Company. It was named 'Toodles V' (after Coatalen's pet name for his wife) and achieved several speed records in 1913 and 1914. The V12 engine had a displacement of , an aluminum crankcase, iron cylinders with L-shaped combustion chambers, a cam-in-block valvetrain and a V-angle of 60 degrees. Each bank of the engine consisted of two cylinder blocks with three cylinders each. Valve clearance was set by grinding the relevant parts, the engine lacking any easy means of adjustment. This reflected the intention for the engine to be later used in aircraft, since any adjustment method that could go wrong in flight was to be avoided. As initially built, the V12 was rated at  at 2,400 rpm and weighed approximately .

Amongst the first production cars to use a V12 engine were the 1915 Packard Twin Six, the 1915  National V12 engine and the 1917 Weidely Pathfinder; all of which were built in the United States.

1920s to 1930s 

Usage of V12 engines in luxury cars increased from the 1920s, including cars such as the 1921 Fiat 520 'Superfiat', the 1926 Daimler Double-Six 50, the 1931 Hispano-Suiza J12, the 1931 Cadillac 370A V-12, the 1932 Auburn V-12 Speedster, the 1931 Lincoln K series, the 1932 Franklin V-12, the 1936 Rolls-Royce Phantom III and the 1936 Pierce-Arrow Twelve. A key benefit of V12 engines during this period was their smoothness, since vibration isolating engine mounts were rarely used prior to the 1930s.

In the United States, V12 engines began to decline in popularity from the 1930s as improvements in combustion chamber design and piston form enabled lighter V8 engines to become more powerful than the V12 engines. The last American V12 engine of the era, the H-Series Lincoln V12 engine, was replaced by a V8 engine in 1949.

1945 to 1960s 

In Europe, V12 engines were seen as excessive in the aftermath of World War II, therefore production of cars with V12 engines was very limited until the 1960s.

The 1948 Ferrari 166 Inter sports car (Ferrari's first road car) was powered by a  SOHC V12 engine. Lamborghini's first car, the 1964 Lamborghini 350 GT was powered by a  DOHC engine. These engines began long histories of V12 engines for the two Italian companies, which continue to the present day.

1970s to present 

In Europe, several manufacturers added V12 engines to their line-up, as listed below:
 Jaguar: The Jaguar V12 engine was an all-aluminium SOHC design with displacements of  that was produced from 1971 to 1997. The first application for the engine was a 5.3 litre version used in the Jaguar E-Type sports car. 
 BMW: Production of V12 engines began with the BMW M70 SOHC engine introduced in the 1987 BMW 750iL luxury sedan. The engine was upgraded to a DOHC V12 engine in 2003, then to a turbocharged DOHC V12 engine which has been in production from 2008 to the present. BMW V12 engines have also been used in several Rolls-Royce models, beginning in 1998 with the Rolls-Royce Silver Seraph.
 Mercedes-Benz: The company's first V12 engine was the Mercedes-Benz M120 engine, a  DOHC engine introduced in the 1991 Mercedes-Benz 600 SE luxury sedan. This engine was replaced by an SOHC V12 engine in 1998, then a turbocharged SOHC V12 engine which has been in production for 2003 to the present. Mercedes-Benz V12 engines have also been used in several Maybach models, beginning with the Maybach 57 and 62 in 2002.
 Aston Martin: The 1999 Aston Martin DB7 V12 Vantage used the company's first V12 engine, a  DOHC design. This engine was replaced by a turbocharged DOHC V12 engine, which was introduced in the Aston Martin DB11 and has been produced from 2016 to the present.
 Audi: The 2008-2012 Audi Q7 SUV was powered by the Audi 6.0 V12 48v TDI engine, which was the first V12 diesel engine used in a production car.

In the United States, no mass-produced V12 engines have been built since the 1940s, with U.S. manufacturers preferring to use large displacement V8 engines instead.

Japanese manufacturers rarely produce engines with large displacements, therefore V12 engines are very rare. The sole Japanese V12 engine is the 1997-2016 Toyota GZ engine, a  SOHC design which was used in the Toyota Century limousine.

In China, the 2009 Hongqi HQE limousine, powered by a  DOHC V12 engine, is the sole Chinese car to be produced with a V12 engine.

Postwar V12 production cars 

This is a list of V12-engined production road cars produced since 1945, sorted alphabetically by make (and sub-sorted by year of introduction):

 Aston Martin DB7 Vantage
 Aston Martin Vanquish
 Aston Martin DB AR1
 Aston Martin DB9
 Aston Martin DBS (2008–12)
 Aston Martin V12 Vantage / V12 Vantage S
 Aston Martin One-77
 Aston Martin Rapide
 Aston Martin Virage (2011–12)
 Aston Martin V12 Zagato
 Aston Martin DB11
 Aston Martin Valkyrie
 Audi Q7 V12 TDI
 B Engineering Edonis
 BMW 750i / 750iL (E32 & E38) / 760i / 760Li (E65 & F01)
 BMW 850i / Ci / CSi
 Bugatti EB110
 Bugatti EB112
 Daimler Double Six
 Ferrari 166
 Ferrari 195
 Ferrari 212
 Ferrari 340 / 342 / 375 America
 Ferrari 250
 Ferrari 250 GT Lusso
 Ferrari 410 / 400 Superamerica
 Ferrari 275
 Ferrari 330
 Ferrari 500 Superfast
 Ferrari 365 California
 Ferrari 365 GT 2+2
 Ferrari 365 GTC & GTS
 Ferrari 365 GTB/4 & 365 GTS/4 "Daytona"
 Ferrari 365 GTC/4
 Ferrari 365 GT4 2+2
 Ferrari 400 / 400i / 412
 Ferrari 456 / 456M
 Ferrari 512BB
 Ferrari F50
 Ferrari 550 Maranello / Barchetta Pininfarina
 Ferrari 575M Maranello / Superamerica
 Enzo Ferrari
 Ferrari 612 Scaglietti
 Ferrari 599 GTB Fiorano / 599 GTO
 Ferrari FF
 Ferrari F12berlinetta / F12tdf
 LaFerrari
 Ferrari GTC4Lusso
 Ferrari 812 Superfast
 Hongqi HQE / L7 / L9
 Hongqi L5
 Jaguar E-Type V12
 Jaguar XJ-S
 Jaguar XJ12 & XJ12C
 Jaguar XJR15
 Lagonda Taraf
 Lamborghini 350 GT
 Lamborghini 400 GT
 Lamborghini Islero
 Lamborghini Miura
 Lamborghini Espada
 Lamborghini Jarama
 Lamborghini Countach
 Lamborghini LM002
 Lamborghini Diablo
 Lamborghini Murciélago
 Lamborghini Reventón
 Lamborghini Aventador
 Lamborghini Veneno
 Lamborghini Centenario
 Lamborghini Sián FKP 37
 Lincoln Continental
 Lincoln H-Series
 Lister Storm
 Lotec Sirius
 Maserati MC12
 Maybach 57 and 62
 McLaren F1
 Mercedes-Benz CL600 / CL65 AMG
 Mercedes-Benz S600 / S65 AMG
 Mercedes-Benz SL600 / SL65 AMG / SL70 AMG / SL73 AMG
 Mercedes-Benz CLK GTR AMG
 Mercedes-Benz G65 AMG / Mercedes-AMG G65 / Mercedes-Maybach G650 Landaulet
 Pagani Zonda
 Pagani Huayra
 Panther De Ville
 Panther J72
 Rolls-Royce Silver Seraph / Silver Seraph Park Ward
 Rolls-Royce Phantom VII / VIII
 Rolls-Royce Phantom Drophead Coupé (2007–17)
 Rolls-Royce Phantom Coupé (2008–17)
 Rolls-Royce Cullinan
 Rolls-Royce Ghost
 Rolls-Royce Wraith (2013–)
 Rolls-Royce Dawn
 Toyota Century (G50)
 Tramontana R
 Vector M12

Some tuner companies, such as Brabus, also sell V12 versions of the Mercedes-Benz E-Class and CLS, which were the fastest street-legal sedans upon their respective introductions.

Prototypes/custom made with V12 engines 

 Apollo Intensa Emozione
 Aston Martin Vulcan (not road-legal)
 Audi R8 Le Mans Concept
 BAIC C90L
 BMW Nazca M12 (a concept by Italdesign)
 BMW CS Concept
 BMW M8 Prototype
 Bertone Genesis
 Cadillac Cien
 Chrysler ME Four-Twelve
 Ferrari 365 P Berlinetta Speciale
 Ferrari F12 TRS
 Ferrari FXX (not road-legal)
 Ferrari FXX-K (not road-legal)
 Ferrari P540 Superfast Aperta
 Ford GT90
 Ford Indigo
 Isdera Commendatore 112i
 Jaguar XJ13
 Jaguar XJ220 Concept
 Lamborghini Flying Star II
 Lamborghini LM004
 Laraki Fulgura
 Lincoln Continental (2002 concept)
 Maybach Exelero
 Méga Monte Carlo
 Peugeot 907 (Peugeot's first V12, 2004)
 Rolls-Royce Sweptail
 Toyota Century Royal
 TVR Cerbera Speed Twelve (never entered production)
 Volga V12 Coupe (a one-off custom rebody)
 Yamaha OX99-11
 Zagato Raptor

Motor racing 

V12 engines have often been used if Formula One, particularly during from the 1966 season to the 1969 season. The first V12 engine used in Formula One was in the 1964 Honda RA271 racing car, and continued through to the 1968 Honda RA301 racing car. The 1966 season saw V12 engines become popular, with new V12 engines from Ferrari, Maserati and Weslake. Ferrari's engine debuted in the Ferrari 312 racing car and was used up to the 1975 Ferrari 312B, after which Ferrari switched to a flat-twelve engine. Maserati's engine was introduced in the Cooper T81 and was used until the 1969 Cooper T86. The Weslake V12 engine was used from 1966-1968 and was introduced in the Eagle Mk1 racing car. BRM produced V12 engines from the 1968 BRM P133 racing car until the 1977 BRM P207. The Matra Sports V12 engine was introduced in the 1968 Matra MS11 racing car and used until the 1978 Ligier JS9. Few V12 engines were used in the following decade, with the exception of the Alfa Romeo V12 which was first used by the 1979 Brabham BT48 and used by Alfa Romeo until the 1982 Alfa Romeo 182.

A resurgance of V12 engines in Formula One began in 1989, with the introduction of the Ferrari 640 racing car. Ferrari continued to use V12 engines until the 1995 Ferrari 412 T2 became the last Formula One car to use a V12 engine. The Lamborghini LE3512 engine was used by various teams between 1989 and 1993. The Honda RA122-E engine was first used in the 1991 McLaren MP4/6 and was raced until the 1992 McLaren MP4/7A. The Yamaha OX99 engine was used in the 1990 Brabham BT59 through to the 1992 Brabham BT60.

In prototype sports car racing, the highly successful 2006-2008 Audi R10 TDI used a diesel twin-turbo V12 engine. The Peugeot 908 HDi FAP, introduced in 2007, also used a diesel twin-turbo V12 engine.

Heavy trucks 

Tatra used a  air-cooled naturally aspirated V12 diesel engine in many of their trucks; for instance, the Tatra T813 and uses 19 L air-cooled naturally aspirated or turbo V12 diesel engine in Tatra T815. Some large trucks have been fitted with twin V12s that drive a common shaft, although this is often advertised as a V24.

GMC produced a large gasoline-burning V12 from 1960 to 1965 for trucks, the "Twin-Six"; it was basically GMC's large-capacity truck 351 V6, doubled, with four rocker covers and four exhaust manifolds. Fifty-six major parts are interchangeable between the Twin-Six and all other GMC V6 engines to provide greater parts availability and standardization. Its engine displacement was , and while power was not too impressive at , torque was . For firetrucks the rev limiter was increased to produce  at 3000 rpm and torque was increased to  at 1600–1900 rpm. It was possibly the last gasoline engine used in heavy trucks in the US.

Fire apparatus manufacturer Seagrave used two versions of the Pierce Arrow V-12 motor starting in 1935. After Pierce-Arrow ended production in 1938, Seagrave bought the machine tools and continued to build and offer these engines until 1970. American La France, beginning in 1931, also offered apparatus with a series of V-12 motors built by ALF but developed from the Lycoming BB motor. Both manufacturers stopped offering a V-12 option when fire departments began specifying diesel engines in their orders.

Detroit Diesel produced their Series 53, 71, 92, and 149 engines as V-12s, among other configurations.

Large diesel engines 

V12 is a common configuration for large diesel engines; most are available with differing numbers of cylinders in V configuration to offer a range of power ratings. Many diesel locomotives have V12 engines. Examples include the  12-710 from Electro-Motive Diesel and the  GEVO-12 from GE Transportation.

Large V12 engines are also common in ships. For example, Wärtsilä offers V12 engines with various cylinder bore diameters between  with power output ranging from . These engines are commonly used especially in cruise ships, which may have up to six such main engines. The largest medium-speed diesel engine, Wärtsilä 64, was also offered in V configuration, and a single 12V64 prototype with an output of  was produced for an experimental power plant in the late 1990s.

Railway V12 diesel engines specs 
Railway Diesel engines with 12 cylinder developing  and more:

Tanks and other AFVs 

The V12 is a common configuration for tank and other armoured fighting vehicles (AFVs). Some examples are:
 German Maybach HL120TRM gasoline engine, used on World War II Pz Kpfw III and Pz Kpfw IV tanks.
 British Rolls-Royce Meteor gasoline engine, derived from the Merlin aero-engine, used on World War II Cromwell and Comet tanks and the post-World War II Centurion and Conqueror tanks.
 Russian V-2 (В-2) V-12 diesel engine, used on World War II T-34, KV-1, KV-2 and IS-2 tanks. Most modern Russian diesel engines for MBTs goes back to V-2 base design.
 American Continental AV1790 engine, produced in gasoline and diesel variants, used on all versions of the Patton tank and on the M103 heavy tank. One of these engines was used to power a hot rod style car called the Blastolene Special.
 The 26.6 litre Perkins diesel engine in the Challenger 2 main battle tank and its variants.

See also 

 Flat-twelve engine
 Straight-12 engine
 W12 engine

References 

Category:Piston engine configurations