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V12 engine

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A V12 engine is a V engine with 12 cylinders. Like a straight-6, this configuration has perfect primary and secondary balance no matter which V angle is used and therefore needs no balance shafts. A V12, with two banks of six cylinders angled at 60° or 180° from each other, has even firing with power pulses delivered twice as often per revolution as, and is smoother than a straight-6 because there is always positive net torque output, as with an engine with 7 or more cylinders. This allows for great refinement in a luxury car; in a racing car, the rotating parts can be made much lighter and thus more responsive, since there is no need to use counterweights on the crankshaft as is needed in a 90° V8 and less need for the inertial mass in a flywheel to smooth out the power delivery. In a large, heavy-duty engine, a V12 can run slower than smaller engines, prolonging engine life.

Aviation

V12 engines were first seen in aircraft. By the end of World War I, the V12 configuration was a fairly popular one in the newest and largest fighters and bombers; V12 engines were produced by companies such as Renault and Sunbeam. Many Zeppelins had V12 engines, from German manufacturers Maybach and Daimler. Various US companies produced the Liberty L-12; the Curtiss NC Flying boats, such as the first aircraft to make a transatlantic flight, the NC-4, had a set of four V12 engines.

A number of World War II fighters and bombers used V12 engines such as the Rolls-Royce Merlin, the Klimov VK-107 or the Allison V-1710 on the Allied side, or the Daimler-Benz DB 600 on the German side, these engines were generating about 1,000 horsepower (0.75 MW) at the beginning of the War and about 1,500 horsepower (1.12 MW) at their ultimate evolution stage. The German DB 605D engine even reached 2000 hp (1.50 MW) with methanol-water injection. Their use disappeared quickly after the advent of the jet engine.

V12 road cars

In automobiles, V12 engines have never been common due to their complexity and cost. They are used almost exclusively in expensive sports cars and luxury cars and are sought after for their power and relatively vibration-free operation.

Prior to World War II, twelve-cylinder engines were found in many luxury models, including cars from Cadillac, Packard, Lincoln, Franklin, Rolls-Royce, and Hispano-Suiza. Packard's 1912 "Double Six" is widely regarded as the first production V12 engine.

Postwar, the type lost favor in the United States, where the V8 engine became ubiquitous. Italian sports cars from such makers as Ferrari and Lamborghini used the V12 almost exclusively on their highest-performance vehicles, while Jaguar developed a V12 that was put into production in 1971 and lasted until 1997, the first modern marque to use the engine in a four-door sedan/saloon. Ferrari's newest V12 (used in the 599) is based on the Enzo Ferrari's engine. From 1973-1996, Ferrari also offered a flat 12 engine that was essentially a 180° V12.

German manufacturers Mercedes-Benz and BMW both introduced V12 designs in model year 1992 and 1988, respectively. The BMW-designed V12 also appears in Rolls-Royce cars, while the Mercedes engine is also seen in Maybach cars. Aston Martin introduced a (Cosworth) V12 model in 2000, while Cadillac has contemplated re-introducing the V12 after 60 years with a version of their Cadillac Northstar Engine.

In 1997, Toyota equipped their Century Limousine with a 5.0 L DOHC V-12 (model # 1GZ-FE), making it the first and only Japanese front-engine, rear-wheel drive production car equipped with a V12.

TVR made and tested a 7.7 L V12 called the Speed Twelve, reportedly making 800+ BHP naturally aspirated, but the project was scrapped after the car it was designed for was deemed too powerful for practical use.

A List of Postwar V12 Production Road Cars (Alphabetical by make, sub-sorted by year of introduction):

Sport-utilities:

Concept cars:

Heavy trucks

Tatra uses a 17.6 L air-cooled turbo diesel V12 engine in many of their trucks, for instance the Tatra T813 and Tatra T815. Some trucks have been fitted with twin V12s.

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. 56 major parts are interchangeable between the Twin-Six and all other GMC V-6 engines to provide greater parts availability and standardization Its engine displacement was 702 in³ (11.5 L), and while power was not too impressive at 250 SAE net horsepower (190 kW), torque was 585 lbf·ft (793 N·m). It was possibly the last gasoline engine used in heavy trucks in the United States.

Auto racing

V12 engines used to be common in Formula One and endurance racing. Between 1965 and 1980, Ferrari, Weslake, Honda, BRM, Maserati, Matra, Alfa-Romeo, Lamborghini and Tecno used 12-cylinder engines in Formula One, either V12 or Flat-12, but the Ford (Cosworth) V8 had a slightly better power-to-weight ratio and less fuel consumption, thus it was more successful despite being less powerful than the best V12s. During the same era, V12 engines were superior to V8s in endurance racing, reduced vibrations giving better reliability. In the 1990s, Renault V10 engines proved their superiority against the Ferrari and Honda V12s and the Ford V8. The last V12 engine in Formula One, was the Ferrari 044, in the Ferrari cars driven by Jean Alesi and Gerhard Berger in 1995.

At the Paris motor show 2006 Peugeot presented a new racing car, as well as a luxury saloon concept car, both called 908 and fitted with a V12 Diesel engine producing around or even surpassing 700 DIN HP. This car will take part in the 24 Hours of Le Mans 2007 race.

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.

Mercedes (MTU) manufacture a line of V12 diesel engines for marine use. These engines commonly power craft up to about 100 tonnes in pairwise configurations and range in power from about 1 to 4 MW.

See Also

Piston engine configurations
v • d • e
Type Bourke • Controlled combustion • Deltic •Orbital • Piston • Pistonless (Wankel) • Radial • Rotary • Single • Split cycle • Stelzer • Tschudi
Inline types H · U · Square four · VR · Opposed · X
Stroke cycles Two-stroke cycle • Four-stroke cycle • Six-stroke cycle
Straight Single · 2 · 3 · 4 · 5 · 6 · 8 · 10 · 12 · 14
Flat 2 · 4 · 6 · 8 · 10 · 12 · 16
V 4 · 5 · 6 · 8 · 10 · 12 · 16 · 20 · 24
W 8 · 12 · 16 · 18
Valves Cylinder head porting • Corliss • Slide • Manifold • Multi • Piston • Poppet • Sleeve • Rotary valve • Variable valve timing • Camless
Mechanisms Cam • Connecting rod • Crank • Crank substitute • Crankshaft • Scotch Yoke • Swashplate • Rhombic drive
Linkages Evans • Peaucellier–Lipkin • Sector straight-line • Watt's (parallel)
Other Hemi • Recuperator • Turbo-compounding


External links

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