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. V12 engines are more common than V10 engines, however they are less common than V8 engines.
The first V12 engine was built in 1904 for use in racing boats. Due to the balanced nature of the engine and the smooth delivery of power, V12 engines were popular in early luxury automobiles, boats, aircraft and tanks. V12 engines reached their apogee during World War II, following which they were mostly replaced by jet engines. In Formula One racing, V12 engines were popular during the late 1960s and early 1990s.
The most common use of V12 engines in the 21st century has been marine engines, large stationary engines and European sports/luxury cars.
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. Many V12 engines use a V-angle of 60 degrees between the two banks of cylinders. 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.
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.
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 18.4 L (1,120 cu in) a weight of 430 kg (950 lb) and developed 110 kW (150 bhp). 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 25.5 L (1,559 cu in) engine for the company's 32-foot 'Lamb IV' boat. The Orleans Motor Company built a massive 56.8 L (3,464 cu in) flathead V12 engine with a power output quoted as "nearly 400 bhp (298 kW)". In 1914, Panhard built two 38.6 L (2,356 cu in) V12 engines with four valves per cylinder, which were designed for use in racing boats.
Large V12 diesel engines are common modern cruise ships, which may have up to six such engines. An example of a currently produced V12 marine engine is the Wärtsilä 46F engine, where the V12 version has a displacement of 1,157 L (70,604 cu in) and a power output of 14,400 kW (19,300 hp).
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 12.2 L (740 cu in), a weight of 350 kg (772 lb) and produced 103 kW (138 hp) 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 13.2 L (806 cu in), weighed 289 kg (637 lb) and produced 104 kW (140 hp) 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 168 kW (225 hp) 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 257 kW (345 hp). 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).
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 750 kW (1,000 hp) at the beginning of the war and over 1,100 kW (1,500 hp) 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.
In the United States, the Rolls-Royce Merlin engine was produced under license by Packard Motor Car Company, 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.
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.
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 9.0 L (549 cu in), 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 150 kW (200 bhp) at 2,400 rpm and weighed approximately 340 kg (750 lb).
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.
Usage of V12 engines in luxury cars increased from the 1920s,[page needed] including cars such as the 1921 Fiat 520 'Superfiat', the 1926 Daimler Double-Six 50,[page needed] 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.
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 2.0 L (122 cu in) SOHC V12 engine. Lamborghini's first car, the 1964 Lamborghini 350 GT was powered by a 3.5 L (211 cu in) DOHC engine. These engines began long histories of V12 engines for the two Italian companies, which continue to the present day.
In Europe, several manufacturers added V12 engines to their line-up, as listed below:
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 5.0 L (305 cu in) SOHC design which was used in the Toyota Century limousine.
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 resurgence 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.
Several truck manufacturers have produced V12 diesel engines at various times. For example, the 1967-1982 Tatra T813, built in Czechoslovakia, used a 17.6 L (1,074 cu in) naturally aspirated V12 diesel engine, and the 1983-present Tatra T815 is available with a 19.0 L (1,159 cu in) V12 diesel engine in both naturally aspirated and turbocharged forms. In the United States, V12 versions of the 1938-1995 Detroit Diesel Series 71, the 1967-1999 Detroit Diesel Series 149 and the 1974-1995 Detroit Diesel Series 92 were produced.
Trucks using V12 gasoline (petrol) engines are rare, however several were produced in the United States from the 1930s until the 1970s. In 1931, American La France began producing firetrucks with V12 gasoline engines based on the Lycoming BB motor. In 1935, the V12 engine used by the Pierce Arrow luxury car was fitted to firetrucks built by Seagrave (with production continuing until 1970, since Seagrave purchased the equipment to manufacture the Pierce Arrow engines themselves). The 1960-1965 GMC Twin Six 11.5 L (702 cu in) gasoline V12 engine was basically the GMC 351 V6 engine, doubled, with four rocker covers and four exhaust manifolds. Peak power was only 250 hp (186 kW), however peak torque was 793 N?m (585 lb?ft).
|MTU||R43||170 mm (6.7 in)||195 mm (7.7 in)||53,113 cc (53.113 L)||1800||2400||6000|
|MTU||2000||130 mm (5.1 in)||150 mm (5.9 in)||23,892 cc (23.892 L)||1800||600||3000|
|EMD||710||190 mm (7.5 in)||210 mm (8.3 in)||71,449 cc (71.449 L)||950||2500|
|GE||7FDL||220 mm (8.7 in)||230 mm (9.1 in)||104,917 cc (104.917 L)||1050||2400|
|Cummins||Qs||170 mm (6.7 in)||190 mm (7.5 in)||51,751 cc (51.751 L)||1800||2200|
|MAN||2842||128 mm (5.0 in)||145 mm (5.7 in)||22,390 cc (22.39 L)||2800||580|
|CAT||3512||150 mm (5.9 in)||170 mm (6.7 in)||36,050 cc (36.05 L)||1800||1500|
The V12 is a common engine configuration for tanks and other armoured fighting vehicles. Some examples are: