A
V12 is an
internal combustion engine with 12
cylinders in
V configuration. 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° from each other, has even firing with power pulses delivered twice as often per revolution as, and is much smoother than, a
straight-6. 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 V12 liberty engine; the
Curtiss NC Flying boats, such as the first aircraft to make a
transatlantic flight, the
NC-4, had a set of 4 V12 engines.
A number of
World War II fighters and
bombers used V12 engines such as the
Rolls-Royce Merlin engine 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
Colombo Type 125 "Testa Rossa" engine in a 1961
Ferrari 250TR Spyder]]
In automobiles, V12 engines have never been common, because of their complexity and thus cost. Their use has been thus confined to costly luxury and sports cars, in which they give superlative performance and smoothness characteristics.
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.
Postwar, the type lost favor in the United States, where the
V8 became ubiquitous. Italian sports cars from such makers as
Lamborghini and
Ferrari 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. Ferrari's newest V12 (used in the
456) is an odd 65° unit based on the Ferrari Dino
V6, while the company's flat 12 engine is really a 180° V12.
In the early
1990s, the German manufacturers
Mercedes-Benz and
BMW both introduced V12 designs. The BMW-designed V12 also appears in
Rolls-Royce cars, while the Mercedes engine is also seen in
Maybach cars.
Aston Martin introduced a V12 model in 2001, while Cadillac are re-introducing the V12 after 60 years with a V12 version of their Cadillac Northstar engine range. This engine is to be available initially only in the
Cadillac Escalade luxury SUV.
Toyota equipped their Century Limousine with their own 5.0
litre DOHC V12 engine, designated the 1GZ-FE.
TVR made and used a V12 called Speed Twelve in several of their cars incuding the TVR Speed 12 and TVR Cerbera Speed 12.
A List of Postwar V-12 Production Road Cars (Alphabetical by make, sub-sorted by year of introduction):
Heavy trucks
Tatra uses a 17.6 litre 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 in the 1960s for trucks, the "Twin-Six"; it was basically GMC's large-capacity truck V6, doubled, with four cam covers and four exhaust manifolds. Its
engine displacement was 702 cubic inches (11.5 litre), 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 have used 12 cylinders in Formula One, either V12 or
Flat-12, but the Ford Cosworth
V8 had 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 V8 in Endurance racing, reduced vibrations giving better reliability. In the 1990s the Renault
V10 engines proved their superiority against the
Ferrari and
Honda V12 and the
Ford V8. Now all Formula One cars use
V10 engines.
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.
External links
Category:Piston engine configurations