Wednesday, 23 September 2015

Most Powerful DIESEL Engine in the World

Wärtsilä-Sulzer RTA96-C

If the Seven Wonders of the World was updated for the 21 st century, the Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine could be a contender. If you are a student of the internal combustion engine in all its wonderous configurations, then feast your eyes on this set of numbers which outline the truly astounding engineering feat. It is the most powerful and most efficient engine in the world today.

The Wärtsilä RT-flex96C is a two-stroke turbocharged low-speed diesel engine designed by the Finnish manufacturer Wärtsilä. It is designed for large container ships that run on heavy fuel oil. Its largest 14-cylinder version is 13.5 metres (44 ft) high, 26.59 m (87 ft) long, weighs over 2,300 tonnes, and produces 80,080 kilowatts (107,390 hp). The engine is the largest reciprocating engine in the world.
The 14-cylinder version was put into service in September 2006 aboard the Emma Mærsk. The design is like the older RTA96C engine, with common rail technology instead of traditional camshaft, chain gear, fuel pumps and hydraulic actuators. All this provides the maximum performance at low revolutions per minute (rpm), lower fuel consumption and lower harmful emissions.
The engine has crosshead bearings so that the always-vertical piston rod allows a tight seal under the piston. Consequently, the lubrication of the engine is split: the cylinders and the crankcase use different lubricants, each being specialised for and dedicated to its role. The cylinders are lubricated by continual, timed injection of consumable lubricant, formulated to protect the cylinders from wear and to neutralise the acids formed during combustion of the high-sulfur fuels commonly used. The crosshead design reduces sideways forces on the piston, keeping diametral cylinder liner wear in the order of only about 0.03 mm per 1000 hours.
The descending piston is used to compress incoming combustion air for the adjacent cylinders which also serves to cushion the piston as it approaches bottom dead centre (BDC) to remove some load from the bearings. The engine is uniflow-scavenged by way of exhaust valves that are operated by electronically controlled, common-rail hydraulics, thus eliminating the camshaft.
As of 2006, more than 300 RT-flex96C engines and older RTA96C engines were in service or on order.

Designed to provide the motive force for a variety of supertankers and container ships, it comes in 6 cylinder in-line through to a whopping 14 cylinder version. The cylinder bore is 38 inches and the stroke is just over 98 inches. Each cylinder displaces 111,143 cubic inches (1820 litres) and produces 7780 horsepower. Total displacement comes out to 1,556,002 cubic inches (25,480 litres) for the 14-cylinder version.
At a length of 89 feet and a height of 44 feet, the total engine weight is 2300 tons - the crankshaft alone weighs 300 tons.
The RTA96C-14 can achieve a maximum power output of 108,920 hp at 102 rpm and astonishingly, at maximum economy the engine exceeds 50% thermal efficiency. That means, more than 50% of the energy in the fuel is converted to motion. Its Brake Specific Fuel Consumption (BSFC) at maximum power is 0.278 lbs/hp/hr.
Ship owners like a single engine/single propeller design and the new generation of larger container ships needed a bigger engine to propel them.While engine cylinder configurations for large-scale container liners have been discussed in the magnitude of 14, 16 and 18 cylinders, the 14-cylinder in-line low-speed engine is the first to be offered by any engine designer.
Ship owners prefer single engine/single propeller designs and the new generation of larger container ships (or post-Panamax) called for a bigger engine to propel them.

Technical data (as of 2008)

Configuration Turbocharged two-stroke diesel straight engine, 6 to 14 cylinders
Bore 960 mm
Stroke 2,500 mm
Displacement 1,820 litres per cylinder
Engine speed 22–102 RPM
Mean effective pressure 1.96 MPa @ full load, 1.37 MPa @ maximum efficiency (85% load)
Mean piston speed 8.5 meters per second
Specific fuel consumption 171 g/(kW·h)
Power Up to 5,720 kW per cylinder, 34,320–80,080 kW (46,680–108,920 BHP) total
Torque Up to 7,603,850 newton metres (5,608,310 lbf·ft) @ 102 rpm
Power density 29.6 to 34.8 kW per tonne, 2300 tonnes for the 14 cylinder version
Mass of fuel injected per cylinder per cycle ~160 g (about 6.5 ounces) @ full load (Whole motor uses up to 250 tons of fuel per day.)
Crankshaft weight 300 tons
Piston weight 5.5 tons
Piston Height 20 feet

The RTA96C-14 turbocharged two-stroke diesel engine is produced by Swiss company Wartsila-Sulzer and is the largest and most powerful diesel engine in the world today.
The peak capabilities of the 14-cylinder RTA96C engine now exceed 80 MW, making it adequate for a single-screw Post-Panamax container liner, which is as large as container liners will get considering their greater cost-effectiveness.
Sulzer have also managed to increase cylinder output since they began first operation in 1997, due to the maintenance experience accumulated with the large number of RTA96C engines currently in service. The new kW rating of the new engine achieves a power output of 68,640 kW, a four percent increase on the initial RTA96C.
Despite the large amounts of power produced by these engines, surprisingly low wear rates have been achieved. Diametral cylinder liner wear is in the order of only about 0.03 mm/1000 hours.
This low cylinder wear is possibly attributed to a connecting rod that attaches to a "crosshead" which rides in guide channels, a fundamental difference to most automotive engines where the top of the connecting rod is attached directly to the piston. Instead, in this engine the top of the connecting rod attaches to a "crosshead" and a long piston rod then connects the crosshead to the piston. This lowers the sideways forces produced by the connecting rod and is absorbed by the crosshead and not by the piston. Sideways forces are what makes the cylinders in an auto engine become oval-shaped over time.
Fuel consumption at maximum economy is 0.260 lbs/hp/hour. Comparatively, most automotive and small aircraft engines can only achieve BSFC figures in the 0.40-0.60 lbs/hp/hr range and 25-30% thermal efficiency range.

The design and development of the RTA96C was close collaboration with the companies involved in the early stages of the first commercial project: the owner and operator P&O Nedlloyd BV, the ship designer and builder Ishikawajima Harima Heavy Industries Co Ltd (IHI), and the enginebuilder Diesel United Ltd.
The project began in March 1997 when the first engine, an 11-cylinder unit, was started on the test bed of Diesel United Ltd, Aioi.
Since then a total of 86 RT96C engines with eight, nine, ten, 11 and 12 cylinders in-line are in service or on order, 25 of these currently in service.

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W12 Engine

A W12 engine is a twelve cylinder piston internal combustion engine in a W configuration. W12 engines have been manufactured in two distinct configurations. The original W12 configuration used three banks of four cylinders coupled to a common crankshaft, with 60° angles between the banks. These were used in several aircraft engine designs from the 1920s, notably the Napier Lion and various French engines. The more recent configuration, used in the Volkswagen Group W12, uses four rows of three cylinders merged into two 'cylinder banks' (two narrow-angle VR6 engine blocks), coupled to a common crankshaft.

Aircraft engines (three-bank)

Napier Lion

The Napier Lion was a broad arrow-style W12 engine produced by Napier at Acton, West London, from 1917 to the late 1930s. This mostly alloy engine had a capacity of 24 litres (1,465 cu in) and produced from 450 to 900 horsepower (336 to 671 kW; 456 to 912 PS). It was used in many racing cars by John Cobb and Malcolm Campbell, racing aircraft such as the Supermarine S.5 Schneider Cup winner, and speed boats such as Hubert Scott-Paine's Miss Britain III.

Other Broad Arrow aircraft engines

The 500 hp (373 kW) Farman 12We was one of their best selling engines in the 1920s. They also built a W18.
Lorraine manufactured their 12E Courlis aircraft engine in the 1920s and 1930s.
Sunbeam built a prototype W12 called the "Kaffir", based on their Arab V8 engine.

Motor racing engines (three-bank)

In the late 1980s, two W12 engines were designed and built for use in Formula One.


In France, Guy Negre produced the MGN which had three banks of four cylinders offset so that each crankpin accommodated three connecting rods side-by-side. The MGN also had a novel system of cylindrical rotary valves located at the top of the combustion chambers, making the engine notably compact. The engine was tested in an AGS Formula One car, and in a Norma sports car, but never raced.

Life F35

The other W12 Formula One engine was the Life F35 built in Italy by Life Racing Engines. The chief engineer for this project was Franco Rocchi, who had already designed and built an experimental 498 cubic centimetres (30.4 cu in) W3 engine when he was at Ferrari in 1967 as an investigation into the viability of a W18 F1 engine. Rocchi's W3 engine used a central master connecting rod, with a slave rod locating onto each side of the master rod, rather than directly onto the crank pin. This meant that there was no offset between the cylinders, and the crankpin did not have to be unusually long. A similar arrangement was employed for the Life W12 engine. Life Racing Engines failed to attract the interest of an existing team, so they acquired an F1 chassis which had been built for another team and tried to enter F1 on their own account in 1990. The engine proved to be unreliable and lacking in power. The car never got out of prequalifying in 14 attempts.

Audi Avus show car (three-bank)

The Audi Avus prototype was shown at the 1991 Tokyo Motor Show. The engine was described as a traditional W12 with three banks of four cylinders each set at 60° to each other. The DOHC W12 engine was said to produce 509 hp (380 kW) at 5800 rpm.

Volkswagen Group W12

At the 2001 Tokyo Motor Show, Volkswagen Group showcased a prototype Volkswagen Nardo W12 Coupé, a mid-engined, rear-wheel drive
supercar powered by a 6.0 litre W12 engine, producing 600 horsepower (447 kW; 608 PS). A week before, the W12 Coupe broke the 24 hour world endurance record. A total distance of 7,085.7 kilometres (4,402.8 mi) was covered at an average speed of 295.24 kilometres per hour (183.45 mph), breaking the old record by 12 kilometres per hour (7.5 mph). Production of the W12 Coupé was considered, but was subsequently cancelled.
Volkswagen Group currently produces W12 engines. It is constructed by mating two narrow-angle 15° VR6 engines at an inclined angle of 72°. The narrow angle of each set of cylinders allows just two overhead camshafts to drive each pair of banks, so just four are needed in total. Note that this design differs from the W18 engine that Volkswagen Group produced for its Bugatti concept cars of 1998 and 1999. Due to this distinction, the Volkswagen Group's W12 engine is sometimes described as a "WR12".
The advantage of the W12 engine is its compact packaging, allowing Audi to build a 12-cylinder sedan with all-wheel drive, whereas a conventional V12 engine could only have a rear-wheel drive configuration as it would have no space in the engine bay for a differential and other components required to power the front wheels. The 6.0L W12 in the Audi A8L W12 (only offered in the long-wheelbase models) appears slightly smaller overall than the 4.2L V8 that powers the Audi A8 4.2 variants. However the W12 engine is not as smooth as the V12.
The 2011 Audi A8L W12 debuted a revised 6.3 litre directly-injected version of the W12 (WR12) engine with 500 PS.

The Volkswagen Group W12 engine is used in some high-end luxury models:

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Monday, 10 March 2014


A V24 engine is a V engine with 24 cylinders, suitable only for very large trucks or locomotives.
Unlike smaller V16 and V20 engines, very few V24s were originally designed with 24 cylinders. The majority of these engines are formed by coupling multiple smaller engines together. For example, a very large V24, the AS.6, engine was built by Fiat in the early 1930s as a powerplant for the competition aeroplane Macchi M.C.72. This engine was in reality formed by mounting two Fiat AS.5 V12s, one behind the other, obtaining a total displacement of over 50 litres (3,051 cu in) and a power output of about 3,100 horsepower (2,310 kW). The two units remained separated (they could be started separately) but the output shaft was shared. Between the units sat the gearbox that was used to reduce the propeller speed, and the final output shaft ran between the cylinder banks of the front engine to reach the nose of the aeroplane.
The Detroit Diesel 24V-71 is an example of a modern, two-stroke V24 Diesel engine. It is capable of producing 1,800 horsepower from a 27.9 liter displacement.

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A V18 engine is a V engine with 18 cylinders. A rare configuration not used in automobiles, large V18 diesel engines have seen limited use in mining, electricity generation, rail transport, and marine propulsion.

Examples of V18 engines

Name Displacement Power output Fuel Notes
ALCO 18-251[1] 12,024 cu in (197.04 l) 4,500 hp (3.36 MW) Diesel Originally designed and manufactured by
American Locomotive Company; now manufactured by
Fairbanks Morse Engine.[1]
Cummins QSK78[2] 4,735 cu in (77.59 l) 3,500 hp (2.61 MW) Diesel Derived from the V16 QSK60.[2]
Marketed by Komatsu as the SSDA18V170.[3]
Wärtsilä 18V50DF[4]  125,000 cu in (2,050 l) 23,530 hp (17.55 MW)   Diesel or
natural gas
Available for both marine propulsion and power generation, and used in e.g. Humbolt Bay power station.[5]

Vehicles powered by V18 engines

Name Description Engine
Belaz 75600 haul truck Cummins QSK78
Liebherr T 282B haul truck Cummins QSK78
Komatsu 960E-1 haul truck Komatsu SSDA18V170
MLW M640 diesel-electric locomotive ALCO 18-251

Wednesday, 15 January 2014


A V6 engine is a V engine with six cylinders mounted on the crankcase in two banks of three cylinders, usually set at either a right angle or an acute angle to each other, with all six pistons driving a common crankshaft. It is the second most common engine configuration in modern cars after the inline four.
The V6 is one of the most compact engine configurations, shorter than the inline-4 and in many designs narrower than the V8. Owing to its compact length, the V6 lends itself well to the widely used transverse engine front-wheel drive layout. It is becoming more common as the space allowed for engines in modern cars is reduced at the same time as power requirements increase, and has largely replaced the straight-six engine, which is too long to fit in many modern engine compartments. The V6 engine has become widely adopted for medium-sized cars, often as an optional engine where an inline-4 is standard, or as a base engine where a V8 is a higher-cost performance option.
Recent forced induction V6 engines have delivered horsepower and torque output comparable to contemporary larger displacement, naturally aspirated V8 engines, while reducing fuel consumption and emissions, such as the Volkswagen Group's 3.0 TFSI which is supercharged and directly injected, and Ford Motor Company's turbocharged and directly injected EcoBoost V6, both of which have been compared to Volkswagen's 4.2 V8 engine.
Modern V6 engines commonly range in displacement from 2.5 to 4.0 L (150 to 240 cu in), though larger and smaller examples have been produced.


Marmona First Car With V6 Engine
Some of the first V6-cars were built in 1905 by Marmon .Marmon was something of a V-Specialist which began with V2-engines, then built V4's and V6's, later V8's and in the 1930s Marmon was one of the few car-makers of the world which ever built a V16 car.
From 1908 to 1913 the Deutz Gasmotoren Fabrik produced benzene electric trainsets (Hybrid) which used a V6 as generator-engine.
Another V6-car was designed in 1918 by Leo Goosen for Buick Chief Engineer Walter L. Marr. Only one prototype Buick V6 car was built in 1918 and was long used by the Marr family.
The first series production V6 was introduced by Lancia in 1950 with the Lancia Aurelia. Other
Lancia Aurelia GT 1957 With V6 Engine
manufacturers took note and soon other V6 engines were in use. In 1959 GMC introduced a unique 60-degree heavy-duty 305 in 3 (5 L) 60° V6 for use in their pickup trucks and Suburbans, an engine design that was later enlarged to 478 in 3 (7.8 L) for heavy truck and bus use. The discovery of the sweet spot of 60 degrees maximized power while minimizing vibration and size. In short, GMC chanced on an optimal design at a time when the straight-six engine was considered the pinnacle of 6-cylinder design.
Suburban Whit Seingle Drivers Side Door 1968 With V6 Engine

1962 saw the introduction of the Buick Special, which offered a 90° V6 with uneven firing intervals that shared some parts commonality with a small Buick V8 of the period. GM sold the engine tooling to Kaiser-Jeep in 1967, then repurchased it in 1974. In 1977, Buick introduced a split pin crankshaft to implement an even-fire version of the engine.

Balance and smoothness

Due to the odd number of cylinders in each bank, V6 designs are inherently unbalanced, regardless of their
Special was the first American car to use a V6 engine
V-angle. Each cylinder bank in a V6 has an odd number of pistons, so the V6 also suffers from the same problem unless steps are taken to mitigate it. In the horizontally opposed flat-6 layout, the rocking motions of the two straight cylinder banks offset each other, while in the straight-six engine layout, the two ends of engine are mirror images of each other and compensate every rocking motion. Concentrating on the first order rocking motion, the V6 can be modeled as two separate straight-3 engines where counterweights on the crankshaft and a counter rotating balance shaft compensate the first order rocking motion. At mating, the angle between the banks and the angle between the crankshafts can be varied so that the balancer shafts cancel each other in the 90° V6 (larger counter weights) and in the even firing 60° V6 with 60° flying arms (smaller counter weights, second order rocking motion balanced by a single co-rotating balancer shaft).

A 90° V6 can use almost the same technique that balances an even firing 90° crossplane V8 in primary and
Lancia B50 Cabriolet With V6 Engine
secondary order. A flatplane V8 is in primary balance because each 4-cylinder bank is in primary balance. In a crossplane V8, balance is achieved at each cylinder pair, since the primary imbalance of a 90° pair is a special case that can be cancelled with a crankshaft counterweight. Secondary balance is achieved by the staggered arrangement of the crossplane crank. A simple 90° V6 with crankshaft counterweights achieves good balance for similar reasons, although the uneven firing intervals will be perceived as roughness at low RPM, making this an unpopular solution. Therefore, designing a smooth V6 engine is a much more complicated problem than the straight-6, flat-6, and V8 layouts. Although the use of offset crankpins, counterweights, and flying arms has reduced the problem to a minor second-order vibration in modern designs, all V6s can benefit from the addition of auxiliary balance shafts to make them completely smooth.

When Lancia pioneered the V6 in 1950, they used a 60° angle between the cylinder banks and a six-throw crankshaft to achieve equally spaced firing intervals of 120°. This still has some balance and secondary vibration problems. When Buick designed a 90° V6 based on their 90° V8, they initially used a simpler three-throw crankshaft laid out in the same manner as the V8 with pairs of connecting rods sharing the same crankpin, which resulted in firing intervals alternating between 90° and 150°. This produced a rough-running design which was unacceptable to many customers. Arguably, the roughness is in the exhaust note, rather
Lancia Aurelia-B10 With V6 Engine
than noticeable vibration, so the perceived smoothness is rather good at higher RPM. Later, Buick and other manufacturers refined the design by using a split-pin crankshaft which achieved a regular 120° firing interval by staggering adjacent crankpins by 15° in opposite directions to eliminate the uneven firing and make the engine reasonably smooth. Some manufacturers such as Buick in later versions of their V6 and Mercedes Benz have taken the 90° design a step further by adding a balancing shaft to offset the primary vibrations and produce an almost fully balanced engine.

Some designers have reverted to a 60° angle between cylinder banks, which produces a more compact engine, but have used three-throw crankshafts with flying arms between the crankpins of each throw to achieve even 120° angles between firing intervals. This has the additional advantage that the flying arms can be weighted for balancing purposes. This still leaves an unbalanced primary couple, which is offset by counterweights on the crankshaft and flywheel to leave a small secondary couple, which can be absorbed by carefully designed engine mounts.
Six-cylinder designs are also more suitable for larger displacement engines than four-cylinder ones because power strokes of pistons overlap. In a four-cylinder engine, only one piston is on a power stroke at any given time. Each piston comes to a complete stop and reverses direction before the next one starts its power stroke, which results in a gap between power strokes and noticeable vibrations. In a six-cylinder engine (other than odd-firing V6s), the next piston starts its power stroke 60° before the previous one finishes, which results in smoother delivery of power to the flywheel. In addition, because inertial forces are proportional to piston displacement, high-speed six-cylinder engines will suffer less stress and vibration per piston than an equal displacement engine with fewer cylinders.
Comparing engines on the dynamometer, a typical even-fire V6 shows instantaneous torque peaks of 150% above mean torque and valleys of 125% below mean torque, with a small amount of negative torque (engine torque reversals) between power strokes. On the other hand, a typical four-cylinder engine shows peaks of nearly 300% above mean torque and valleys of 200% below mean torque, with 100% negative torque being delivered between strokes. In contrast, a V8 engine shows peaks of less than 100% above and valleys of less than 100% below mean torque, and torque never goes negative. The even-fire V6 thus ranks between the four and the V8, but closer to the V8, in smoothness of power delivery. An odd-fire V6, on the other hand, shows highly irregular torque variations of 200% above and 175% below mean torque, which is significantly worse than an even-fire V6, and in addition the power delivery shows large harmonic vibrations that have been known to destroy the dynamometer.

V angles

60 degrees
The most efficient cylinder bank angle for a V6 is 60 degrees, minimizing size and vibration. While 60° V6 engines are not as well balanced as inline-6 and flat-6 engines, modern techniques for designing and mounting engines have largely disguised their vibrations. Unlike most other angles, 60-degree V6 engines can be made acceptably smooth without the need for balance shafts. When Lancia pioneered the 60° V6 in 1950, a 6-throw crankshaft was used to give equal firing intervals of 120°. However, more modern designs often use a 3-throw crankshaft with what are termed flying arms between the crankpins, which not only give the required 120° separation but also can be used for balancing purposes. Combined with a pair of heavy counterweights on the crankshaft ends, these can eliminate all but a modest secondary imbalance which can easily be damped out by the engine mounts.
1 of 5 made in 1983 in the Breman-Sport factory in Breman, IN. VW chassis & GM 60 degree V6 3.8 liter engine. 54,000 miles. 4W disk brakes. AC. Power top.

This configuration is a good fit in cars which are too big to be powered by four-cylinder engines, but for which compactness and low cost are important. The most common 60° V6s were built by General Motors (the heavy duty commercial models, as well as a design used in many GM front-wheel-drive cars) and Ford European subsidiaries (Essex V6, Cologne V6 and the more recent Duratec V6). Other 60° V6 engines are the Chrysler 3.3 V6 engine, the Nissan VQ engine, the Mazda K engine, the Alfa Romeo V6 engine, many Toyota V6 engines, and later versions of the Mercedes-Benz V6 engine.

90 degrees

90° V6 engines are also produced, usually so they can use the same production-line tooling set up to
produce V8 engines (which normally have a 90° V angle). Although it is relatively easy to derive a 90° V6 from an existing V8 design by simply cutting two cylinders off the engine, this tends to make it wider and more vibration-prone than a 60° V6. The design was first used by Buick when it introduced its 198 CID Fireball V6 as the standard engine in the 1962 Special. Other examples include the Maserati V6 used in the Citroën SM, the PRV V6, the Rover KV6 (2.0litre and 2.5litre, the Honda C engine used in the NSX, Chevrolet's 4.3 L Vortec 4300 and Chrysler's 3.9 L (238 in 3) Magnum V6 and 3.7 L (226 in 3) PowerTech V6. The Buick V6 was notable because it introduced the concept of uneven firing, as a result of using the 90° cylinder bank angle and shared-crankpin crankshaft design found in the V8 engine (although the V6 crankshaft does have 3 crank throws set at 120° apart, rather than 90° apart as found in the V8) . Rather than firing every 120° of crankshaft rotation, the cylinders would fire alternately at 90° and 150°, resulting in strong harmonic vibrations at certain engine speeds. These engines were often referred to by mechanics as "shakers", due to the tendency of the engine to bounce around at idle speed.
More modern 90° V6 engine designs avoid these vibration
problems by using crankshafts with offset split crankpins to make the firing intervals even, and often add balancing shafts to eliminate the other vibration problems. Examples include the later versions of the Buick V6, and earlier versions of the Mercedes-Benz V6. The Mercedes V6, although designed to be built on the same assembly lines as the V8, used split crankpins, a counter-rotating balancing shaft, and careful acoustic design to make it almost as smooth as the inline-6 it replaced. However, in later versions Mercedes changed to a 60° angle, making the engine more compact and allowing elimination of the balancing shaft. Despite the difference in V angles, the Mercedes 60° V6s are built on the same assembly lines as 90° V8s.

120 degrees

120° might be described as the natural angle for a V6 since the cylinders fire every 120° of crankshaft rotation. Unlike the 60° or 90° configuration, it allows pairs of pistons to share crank pins in a three-throw crankshaft without requiring flying arms or split crankpins to be even-firing. However, unlike the crossplane crankshaft V8, there is no way to arrange a V6 so that unbalanced forces from the two cylinder banks will completely cancel each other. As a result, the 120° V6 acts like two straight-3s running on the same crankshaft and, like the straight-3, suffers from a primary dynamic imbalance which requires a balance shaft to offset.
The 120° layout also produces an engine which is too wide for most automobile engine compartments, so it is more often used in racing cars where the car is designed around the engine rather than vice-versa, and vibration is not as important. By comparison, the 180° flat-6 boxer engine is only moderately wider than the 120° V6, and unlike the V6 is a fully balanced configuration with no vibration problems, so it is more commonly used in aircraft and in sports/luxury cars where space is not a constraint and smoothness is important.
Spanish truck manufacturer Pegaso built the first production 120° V6 for the Z-207 mid size truck in 1955. The engine, a 7.5-litre alloy Diesel designed under the direction of engineer Wifredo Ricart uses a single balance shaft rotating at the speed of the crankshaft
Ferrari introduced a very successful 120° V6 racing engine in 1961. The Ferrari Dino 156 engine was shorter and lighter than the 65° Ferrari V6 engines that preceded it, and the simplicity and low center of gravity of the engine was an advantage in racing. It won a large number of Formula One races between 1961 and 1964. However, Enzo Ferrari had a personal dislike of the 120° V6 layout, preferring a 65° angle, and after that time it was replaced by other engines.
Bombardier designed 120° V220/V300T V6 engines for use in light aircraft. The ignition sequence was symmetrical, with each cylinder firing 120° after the previous cylinder resulting in smooth power delivery. A balance shaft on the bottom of the engine offset the primary dynamic imbalance. The straight, pin-type crankshaft journals in the 120° V-6 layout allowed a shorter and stiffer crankshaft than competing flat-6 engines, while water cooling resulted in better temperature control than air cooling. These engines could run on automotive gasoline rather than avgas. However, the design was shelved in 2006 and there are no plans for production.

Other angles

Narrower angle V6 engines are very compact but can suffer from severe vibration problems unless very carefully designed. Notable V6 bank angles include:
  • The 10.6° and 15° Volkswagen VR6 engine, which is such a narrow angle it can use a single cylinder head and double overhead camshafts for both cylinder banks. With seven main bearings, it is more like a staggered-bank in-line six rather than a normal V6, but is only slightly longer and wider than a straight-4.
  • The 45° Electro-Motive 6-, 8-, 12-, 16- and 20-cylinder versions of their 567 Series, 645 Series and 710 Series locomotive, marine and stationary Diesel engines. This angle is optimum for the more common 8- and 16-cylinder versions. In all of these engines, directly opposite cylinders always fire 45 degrees apart, so engines other than 8- and 16-cylinder versions are uneven firing. 6-cylinder engines were only made in the 567 and 645 Series; 20-cylinder engines were only made in the 645 and 710 Series.
  • The 54° GM/Opel V6, designed to be narrower than normal for use in small front-wheel drive cars.
  • The 65° Ferrari Dino V6, allowing larger carburetors (for potentially higher power in race tuning) than a 60° angle, while suffering a slight increase in vibrations.
  • The 72° Mercedes-Benz Bluetec Diesel V6 utilizes a counter-rotating balance shaft and crankpins offset by 48° to eliminate vibration problems and make the engine even-firing.
  • The 75° Isuzu Rodeo and Isuzu Trooper V6 of 3.2 and 3.5 L in both SOHC and DOHC versions.
  • The 80° Honda RA168-E Formula One engine in the McLaren MP4/4.

Odd and even firing

Many older V6 engines were based on V8 engine designs, in which a pair of cylinders was cut off the front of V8 without altering the V angle or using a more sophisticated crankshaft to even out the firing interval. Most V8 engines share a common crankpin between opposite cylinders in each bank, and a 90° V8 crankshaft has just four pins shared by eight cylinders, with two pistons per crankpin, allowing a cylinder to fire every 90° to achieve smooth operation.
Early 90° V6 engines derived from V8 engines had three shared crankpins arranged at 120° from each other. Since the cylinder banks were arranged at 90° to each other, this resulted in a firing pattern with groups of two cylinders separated by 90° of rotation, and groups separated by 150° of rotation, causing a notorious odd-firing behavior, with cylinders firing at alternating 90° and 150° intervals. The uneven firing intervals resulting in rough-running engines with unpleasant harmonic vibrations at certain engine speeds.
An example is the Buick 231 odd-fire, which has a firing order 1-6-5-4-3-2. As the crankshaft is rotated through the 720° required for all cylinders to fire, the following events occur on 30° boundaries:
Angle 90° 180° 270° 360° 450° 540° 630°
Odd firing 1 6 5 4 3 2
Even firing 1 4 5 6 3 2
More modern 90° V6 engines avoid this problem by using split crankpins, with adjacent crankpins offset by 15° in opposite directions to achieve an even 120° ignition pattern. Such a 'split' crankpin is weaker than a straight one, but modern metallurgical techniques can produce a crankshaft that is adequately strong.
In 1977, Buick introduced the new "split-pin crankshaft" in the 231. Using a crankpin that is 'split' and offset by 30° of rotation resulted in smooth, even firing every 120°. However, in 1978 Chevrolet introduced a 90° 200/229 V6, which had a compromise 'semi-even firing' design using a crankpin that was offset by only 18°. This resulted in cylinders firing at 108° and 132°, which had the advantage of reducing vibrations to a more acceptable level and did not require strengthening the crankshaft. In 1985, Chevrolet's 4.3 (later the Vortec 4300) changed it to a true even-firing V6 with a 30° offset, requiring larger crank journals to make them adequately strong.
In 1986, the similarly designed 90° PRV engine adopted the same 30° crankshaft offset design to even out its firing. In 1988, Buick introduced a V6 engine that not only had split crankpins, but had a counter-rotating balancing shaft between the cylinder banks to eliminate almost all primary and secondary vibrations, resulting in a very smooth-running engine.

Racing use

 The V6 engine was introduced into racing by Lancia in the early 1950s. After good results with privately entered Aurelia saloons Lancia set a works competition department in 1951. Four B20 Coupes were entered in the '51 Mille Miglia and the one driven by Giovanni Bracco and Umberto Maglioli caused quite a stir by finishing second overally after the 4.1-litre Ferrari driven by Villoresi and Cassani, a car which had three times more power than the Lancia. After that encouraging start Lancia decided to carry on with the endurance racing program, first with specially prepared Aurelias (called Da Corsa) and then with specially built prototypes. A D24 with a 3,102 cc (189 cu in) V6 making 230 PS (170 kW) won the 1953 Carrera Panamericana with Juan Manuel Fangio at the wheel.

After that came the Ferrari Dino V6. Alfredo Ferrari (nicknamed Dino), son of Enzo Ferrari, suggested to him the development of a 1.5 L DOHC V6 engine for Formula Two at the end of 1955. The Dino V6 underwent several evolutions, including an increased engine displacement to 2,417 cc (147 cu in), for use in the Ferrari 246 Formula One car in 1958.
The use of a wide 120° bank angle is appealing for racing engine designers as it permits a low center of gravity. This design is even considered superior to the flat-6 in that it leaves more space under the engine for exhaust pipes; thus the crankshaft can be placed lower in the car. The Ferrari 156 built for new Formula One 1.5 L regulations used a Dino V6 engine with this configuration.
The Dino V6 engine saw a new evolution in 1966 when it was adapted to road use and produced by a Ferrari-Fiat joint-venture for the Fiat Dino and Dino 206 GT (this car was made by Ferrari but sold under the brand Dino). This new version was redesigned by Aurelio Lampredi initially as a 65° 2.0 L (120 cu in) V6 with an aluminum block but was replaced in 1969 by a 2.4 L (150 cu in) cast-iron block version (the Dino car was renamed the 246GT).
The Fiat Dino and Dino 246GT were phased out in 1974, but 500 engines among the last built were delivered to Lancia, who was like Ferrari already under the control of Fiat. Lancia used them for the Lancia Stratos which would become one of the most successful rally cars of the decade.
The Alfa Romeo V6 was designed in the 1970s by Giuseppe Busso, the first car to use them being the Alfa Romeo 6. The over-square V6, with aluminium alloy block and heads, has seen continuous use in road vehicles, from the Alfetta GTV6 onwards. The 164 introduced a 3.0 L (180 cu in) V6, a 2.0 V6 turbocharged in 1991 and in 1992, a 3.0 L DOHC 24-valve version. The Alfa 156 introduced a 2.5 L DOHC 24-valve version in 1997. The engine capacity was later increased to 3.2 L (200 cu in), where it found application in the 156 GTA, 147 GTA, 166, GT, GTV and Spider 916. Production was discontinued in 2005.
A notable racing use of the V6 engine was the Alfa Romeo 155 V6 TI, designed for the 1993 Deutsche Tourenwagen Meisterschaft season and equipped with a 2.5 L (150 cu in) engine making a peak power of 490 PS (360 kW; 480 hp) at 11,900 rpm.
Another influential V6 design was the Renault-Gordini CH1 V6, designed by François Castaing and Jean-Pierre Boudy, and introduced in 1973 in the Alpine-Renault A440. The CH1 was a 90° cast-iron-block V6, similar to the mass-produced PRV engine in those two respects but otherwise dissimilar. It has been suggested that marketing purposes made the Renault-Gordini V6 adopt those characteristics of the PRV in the hope of associating the two in the public's mind.
Despite such considerations, this engine won the European 2 L prototype championship in 1974 and several European Formula Two titles. This engine was further developed in a turbocharged 2 L version that competed in Sports car and finally won the 24 Hours of Le Mans in 1978 with a Renault-Alpine A 442 chassis.
The capacity of this engine was reduced to 1.5 L to power the Formula One Renault RS01. Despite frequent breakdowns that resulted in the nickname of the 'Little Yellow Teapot', the 1.5 L finally saw good results in 1979.
Ferrari followed Renault in the turbo revolution by introducing a turbocharged derivative of the Dino design (a 1.5 L 120° V6) with the Ferrari 126. However, the 120° design was not considered optimal for the wing cars of the era and later engines used V angles of 90° or less.
Both Renault and Ferrari failed in their attempt to win the Drivers' Championship with V6 Turbo engines. The first turbocharged engine to win the championship was the Straight-4 BMW.
They were followed by a new generation of Formula One engines, the most successful of these being the TAG V6 (designed by Porsche) and the Honda V6. This new generation of engines were characterized by odd V angles (around 80°). The choice of these angles was mainly driven by aerodynamic consideration. Despite their unbalanced designs these engines were both quickly reliable and competitive; this is generally viewed as a consequence of the quick progress of CAD techniques in that era.
In 1989 Shelby tried to bring back the Can-Am series, using the Chrysler 3.3 L (201 cu in) V6 (not yet offered to the general public) as the powerplant in a special racing configuration making 255 hp (190 kW). This was the same year that the Viper concept was shown to the public.
Originally the plan was to produce two versions of this race car, a 255 hp (190 kW) version and a 500 hp (370 kW) model, the 255 hp (190 kW) version being the entry circuit. The cars were designed to be a cheap way for more people to enter auto racing. Since all the cars were identical, the winners were to be the people with the best talent, not the team with the biggest pockets. The engines had Shelby seals on them and could only be repaired by Shelby's shop, ensuring that all the engines are mechanically identical.
Only 100 of these 3.3s were ever built. Of these 100, 76 were put into Shelby Can-Am cars (the only 76 that were ever sold). No significant amount of spare parts were produced, and the unsold engines were used for parts/spares. The Shelby specific parts, such as the upper intake manifold, were never made available to the general public. According to a small article in the USA Today (in 1989), these cars were making 250 hp (190 kW) (stock versions introduced in 1990 produced 150 hp or 110 kW) and hitting 160 mph (260 km/h) on the track. The engine itself was not that far from a standard-production 3.3. The Shelby engine is only making about 50 hp (37 kW) more than the newest 3.3 factory engines from Chrysler. The Can-Am engine has a special Shelby Dodge upper intake manifold, a special Shelby Dodge throttle body, and a special version of the Mopar 3.3 PCM (which had this engine redlining at 6800 rpm).
Nissan also has a quite successful history of using V6's for racing in both IMSA and the JGTC. Development of their V6s for sports cars began in the early 1980s with the VG engine initially used in the Z31 300ZX. The engine began life as a SOHC, turbocharged 3.0L power plant with electronic fuel injection, delivering 230 PS (169 kW). The VG30ET was later revised into the VG30DETT for the Z32 300ZX in 1989. The VG30DETT sported both an additional turbocharger and an extra pair of camshafts, making the engine a genuine DOHC twin-turbo V6 producing 300 PS (221 kW). Nissan used both of these engines in its IMSA racing program throughout the 1980s and 1990s each producing well over 800 hp (600 kW). In the Japan Grand Touring Car Championship, or JGTC, Nissan opted for a turbocharged version of its VQ30 making upwards of 500 hp (370 kW) to compete in the GT500 class.
The V6 turbo engine is to be revived for the 2014 Formula One season, and V6 turbos have been used in the IndyCar Series since 2012, with Chevrolet and Honda currently supplying the engines. Lotus also made engines in the 2012 season, but pulled out at the end of the year.

Motorcycle use

Laverda showed a 996 cc V6-engined motorcycle at the 1977 Milan show. The motorcycle was raced in the 1978 Bol d'Or.

Marine use

V6 engines are popular powerplants in medium to large outboard motors. 

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Tuesday, 31 December 2013


In the beginning, there was the V12. Designed by Giotto Bizzarrini for ambitious tractor magnate Ferruccio Lamborghini, Bizzarini's V12 was fitted to the first Lamborghini, the handsome 1963 350GT. Was that first Lamborghini engine based on Bizzarrini's 1.5-liter Grand Prix screamer, or Honda's similar unit, as suggested by L.J.K. Setright in 1973? Does it matter? And, besides, who would dare ask?

"I know Giotto," said Maurizio Reggiani, Lamborghini's R&D chief. "I've never asked him—there's a thing about respect..."
Reggiani was introducing the new V12, fifth in line from that Bizzarrini original, which has been progressively redesigned over the years and fitted to Formula One cars, offshore-racing powerboats and successive Lamborghini supercars: the Miura, the Countach, the Diablo and the Murciélago.
The new engine follows the pattern of a 60-degree V12 with double overhead camshafts, but the car it will be fitted into, the Murciélago replacement, won't be seen until next spring's Geneva Motor Show. We have a clue as to what it will look like, however, with the all-carbon-fiber Sesto Elemento (Sixth Element) concept car from September's Paris Motor Salon.

"With this new V12, we are heralding a technological leap that encompasses all areas of the company and our future model range," said Stephan Winkelmann, president and CEO of Automobili Lamborghini. "Lamborghini will redefine the future of the super–sports car. This 700-hp engine, together with an all-new concept gearbox, will be at the heart of the Murciélago successor next year."

The Specs

While the novelty of an all-new V12 engine is intriguing, especially in this age of tighter fuel-economy regulations, the really startling thing about this unit is that Lamborghini has unapologetically stayed with a naturally aspirated engine with conventional port fuel injection rather than adopting the direct injection route taken by its VW-owned sister company, Audi. In other words, at a time when rivals such as Ferrari are seriously talking about smaller-displacement turbocharged, direct-fuel-injected engines, Lamborghini is not just producing a naturally aspirated V12, but it is also an old-school, short-stroke, big-block screamer. The introduction to the engine consisted of a video of the unit singing its heart out at 8,500 rpm on the dynamometer at the company's base in Sant'Agata, near Bologna, Italy. This was a mechanical aria of a premier engine.

The new engine is made of aluminium–silicon alloy, with an open-deck construction and steel cylinder liners. It has a forged steel crankshaft, with twin overhead camshafts and variable timing. At the top end, inlet air is drawn through four throttle bodies into a plenum chamber with internal valves that change the volume, optimizing airflow at a variety of engine speeds. There are two cooling circuits: a small volume system to speed warmup and reduce cold-start emissions, and a larger system for high-temperature control. The exhaust also has valves that open at high revs to divert the flow through a low-restriction (and noisier) muffler.

With a 95-millimeter bore and 76.4-millimeter stroke (the old engine measured 88 and 89 millimeters, respectively), the new motor displaces 6.5 liters. The short-stroke design means this engine was made to rev, and its 700-hp power peak spikes at a lofty 8250 rpm. Torque is likewise strong—509 lb-ft—but that figure also occurs high up in the rev range, 5500 rpm.

Lamborghini claims a "clean sheet" design for the engine, which used several bits of interesting technology. Each pair of pistons runs in its own sealed chamber, which is served by its own scavenge pump—there are eight in all. Each chamber acts as its own air spring, so the downward movement of one piston pushes the opposing piston on the same crankpin upward in opposing vee, reducing frictional losses. It's also a dry-sump design so the engine could be mounted lower in the frame, improving weight distribution for better handling.

Of course, modern electronics are part of the package. And the computer controls nearly everything, including the throttle and even the robotized six-speed transmission and clutch.

The Transmission

Like the Murciélago, the new supercar will be four-wheel drive, via a central electrohydraulically controlled Haldex center coupling. Unlike Ferrari and the VW Group, which utilize dual-clutch automated gearboxes (DSG), Lamborghini is persevering with a robotized single-clutch manual transmission made by Graziano that's operated either automatically or via steering-wheel- mounted paddles. While Lamborghini claims this transmission is lighter and more compact, we generally prefer the smoothness of DSGs. Known as the ISR (independent shifting rods) transmission, the seven-speed (plus reverse) gearbox uses integral plumbing in the casing to actuate shifts. The unit has carbon-fiber synchros. Shift times have been reduced by up to 50 percent, and Lamborghini claims that in its fastest, or Corsa mode, shift times can be as low as 50 milliseconds.

The Bottom Line

While the rest of the world contemplates life without even V8 engines, Lamborghini is unveiling its most outrageous power unit yet. What's more, the company claims the unit will meet all current and next-generation emissions and fuel-consumption regulations. It wouldn't be an option available to a mass-market carmaker, of course, but we're delighted that this motorsport- inspired V12 is far from dead. Giotto Bizzarrini must be delighted.

A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders, usually but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft.
Since each cylinder bank is essentially 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°, 120° or 180° (with the latter configuration usually referred to as a flat-12) from each other has even firing with power pulses delivered twice as often per revolution as 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 displacement, heavy-duty engine, a V12 can run slower than smaller engines, prolonging engine life.

Early (pre WW1) V12 engines

Marine engines

The first V-type engine (a 2-cylinder vee twin) was built in 1889 by Daimler, to a design by Wilhelm Maybach. By 1903 V8 engines were being produced for motor boat racing by the Société Antoinette to designs by Léon Levavasseur, building on experience gained with in-line four-cylinder engines. In 1904, the Putney Motor Works completed a new V12 marine racing engine – the first V12 engine produced for any purpose. Known as the ‘Craig-Dörwald’ engine after Putney’s founding partners, the engine mounted pairs of L-head cylinders at a 90 degree included angle on an aluminium crankcase, using the same cylinder pairs that powered the company’s standard 2-cylinder car. A single camshaft mounted in the central vee operated the valves directly. 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. "Starting is by pumping a charge into each cylinder and switching on the trembler coils. A sliding camshaft gave direct reversing. The camshaft has fluted webs and main bearings in graduated thickness from the largest at the flywheel end." Displacing 1,119.9 cuin (18,352 cc) (bore and stroke of 4.875" x 5" (123.8 x 127 mm)), the engine weighed 950 pounds (430 kg) and developed 150 bhp (110 kW). Little is known of the engine's achievements in the 40-foot hull for which it was intended, while a scheme to use the engine to power heavy freight vehicles never came to fruition. One V12 Dörwald marine engine was found still running in a Hong Kong junk in the late-1960s.
Two more V12s appeared in the 1909-10 motor boat racing season. The Lamb Boat & Engine Company of Clinton, Iowa built a 1,558.6 cuin (25,541 cc (5.25" x 6" (133.4 x 152.4 mm)) engine for the company’s 32-foot Lamb IV. It weighed in at 2,114 pounds (959 kg). No weight is known for the massive 3,463.6 cuin (56,758 cc) (7" x 7.5" (177.8 x 190.5 mm)) F-head engine built by the Orleans Motor Company. Output is quoted as “nearly 400 bhp (300 kW)”.
By 1914, when Panhard built two 2,356.2 cuin (38,611 cc) (5" x 10" (127 x 254 mm)) engines with four-valve cylinder heads the V12 was well established in motor boat racing.

Motor car engines

In October 1913 Louis Coatalen, chief engineer of the Sunbeam car company entered a V12 powered car in the Brooklands short and long handicap races. The engine displaced 9,048 cc (552.1 cuin), with bore and stroke of 80 x 150 mm. An aluminium crankcase carried two blocks of three cylinders along each side, with a 60 degree included angle. The cylinders were of iron, with integral cylinder heads with L-shaped combustion chambers. Inlet and exhaust valves were operated by a central camshaft in the vee. Valve clearance was set by grinding the relevant parts, the engine lacking any easy means of adjustment. This pointed to Coatalen’s ultimate aim of using the new V12 as an aero engine, where any adjustment method that could go wrong in flight was to be avoided. As initially built the V12 was rated at 200 bhp (150 kW) at 2,400 rpm, weighing about 750 pounds (340 kg). The engine powered the car (named ‘Toodles V’ (for Coatalen’s wife Olive’s pet name) to several records in 1913 and 1914.

Early aero engines

In 1909 Renault pioneered aero V12s with a 60 degree air-cooled engine with individual finned cylinders and F-head valve arrangement, driven by single camshaft in the crankcase. This was developed to a 12,160 cc (742.1 cuin) unit (96 x 140 mm) which weighed 772 pounds (350 kg) and produced 138 bhp (103 kW) at 1,800 rpm. The propeller was driven from the nose of the camshaft in the central vee, rather than from the crankshaft, thus providing an automatic half-speed reduction, improving propeller efficiency.
Renault’s designs were closely followed in Britain by the Royal Aircraft Factory. Its RAF 4 engine displaced 13,195 cc (805.2 cuin)(100 x 140 mm), produced 140 bhp (100 kW) at 1,800 rpm, for a weight of 637 pounds (289 kg). Its RAF 4a derivative was produced in substantial numbers during the war.
By 1912 ABC were offering a water-cooled engine of 17,375 cc (1,060.3 cuin), claimed to produce 170 bhp (130 kW) at 1,400 rpm and weigh 390 pounds (180 kg) – 520 pounds (240 kg) with radiator and coolant.
In March 1914 Sunbeam exhibited an airborne version of Toodles V’s engine at Olympia. Racing in 1913 had helped to prove the design, and encouraged a 10 mm increase in bore to 90 m, the stroke remaining at 150 mm. Its rated output was 225 bhp (168 kW) at 2,000 rpm. Named the ‘Mohawk’, the engine was the most powerful available to British aviation at the outbreak of WW1. During the war further enlargement to 100 x 150 mm created the 240 bhp (180 kW) ‘Gurkha’.

Later V12s in aviation

 By the end of World War I, V12s were well established in aviation, powering some of the newest and largest fighters and bombers and being produced by companies such as Renault and Sunbeam. Many Zeppelins had 12-cylinder engines from German manufacturers Maybach and Daimler. Various U.S. companies produced the Liberty L-12. Soon after the end of WW1 V12 engines powered the first trans-atlantic crossings by the Curtiss NC Flying boats (4 x Liberty L-12), the first non-stop crossing by Alcock and Brown in a Vickers Vimy (2× Rolls-Royce Eagles and the first airship crossing by HM airship R-34 (5× Sunbeam Maori).

 V12 engines reached their apogee during World War II. Fighters and bombers used V12 engines such as the British Rolls-Royce Merlin and Griffon, the Soviet Klimov VK-107 and Mikulin AM-38, the American Allison V-1710, or the German Daimler-Benz DB 600 series and Junkers-Jumo. These engines generated about 1,000 hp (750 kW) at the beginning of the war and above 1,500 hp (1,100 kW) at their ultimate evolution stage. The German DB 605D engine reached 2,000 hp (1,500 kW) with water injection. In contrast to most Allied V12s, the engines built in Germany by Daimler-Benz, Junkers-Jumo, and Argus (As 410 and As 411) were primarily inverted, which had the advantages of lower centers of gravity and improved visibility for single-engined designs. Only the pre-war origin BMW VI V12 of Germany was an "upright" engine. The United States had the experimental Continental IV-1430 inverted V12 engine under development, with a higher power-to-weight ratio than any of the initial versions of the German WW II inverted V12s, but was never developed to production status, with only 23 examples of the Continental inverted V12 ever being built. 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 found use in stateside-based training aircraft like the Fairchild AT-21 Gunner twin-engined "advanced" trainer.

The Rolls-Royce Merlin V12 powered the Hawker Hurricane and Supermarine Spitfire fighters that played a vital role in Britain's victory 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 Avro Lancaster and de Havilland Mosquito bombers. In the United States the Packard Motor company was licensed by Rolls-Royce to produce the Merlin as the Packard V-1650 for use in the North American P-51 Mustang. It 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 only indigenous U.S.-developed V12 liquid-cooled engine to see service during World War II. A sturdy design, it lacked an advanced mechanical supercharger until 1943. Although versions with a turbosupercharger provided excellent performance at high altitude in the Lockheed P-38 Lightning, the turbosupercharger and its ductwork were too bulky to fit into typical single-engine fighters. While a good performer at low altitudes, without adequate supercharging, the Allison's high-altitude performance was lacking.
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.

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