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V6: Difference between revisions

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[[Image:180px-FordEssexV6.jpg|thumb|right|The [[Ford Essex V6 engine]]]]
#REDIRECT [[V6 engine]]
{{Redirect2|[[V6|V6]]|[[V6|V-6]]}}
 
A '''[[V6|V6]] engine''' is a [[V engine]] with six [[cylinder (engine)|cylinder]]s. It is the second most common engine configuration in modern cars after the [[straight-4]]; it shares with that engine a compactness very suited to the popular [[front-wheel drive]] layout, and is becoming more popular as car weights increase.
 
The first [[V6|V6]] was introduced by [[Lancia]] in [[1950]] with the [[Lancia Aurelia]], other manufacturers took note and soon other [[V6|V6]] engines were in use. The design really took off after the 1962 introduction of the [[Buick Special]]. Though the model was not a spectacular success, it was the first mass-produced [[V6|V6]] engine.
 
==Vee angles==
A [[V6|V6]] is not a perfectly balanced engine and benefits from some [[balance shaft|counterbalancing]] and harmonic damping. The optimal angle to minimize vibrations in the [[V6|V6]] is 60°, and this is commonly used. The most common 60° V6s were built by Ford European subsidiaries : [[Ford Essex V6 engine (UK)|Essex V6]], [[Ford Cologne V6 engine|Cologne V6]] and the more recent [[Ford Duratec|Duratec V6]]. The [[Alfa-Romeo]] [[V6|V6]] is also common.
 
90° [[V6|V6]] engines have also been produced, often to take advantage of production-line machinery set up for V8 engines (for which 90° is optimal). This design was first used by [[Buick]] when it introduced its [[Buick V6 engine#198|198 in³ ''Fireball V6'']] as the standard engine in the [[1962]] [[Buick Special|Special]]. Other examples include the [[Maserati]] [[V6|V6]] used in the [[Citroën SM]], the [[PRV engine|PRV]] [[V6|V6]], [[Chevrolet]]'s [[GM Vortec engine#4300|4.3 L ''Vortec 4300'']] and [[Chrysler Corporation|Chrysler]]'s [[Chrysler LA engine#238|3.9 L ''Magnum V6'']] and [[Chrysler PowerTech engine#3.7|3.7 L ''PowerTech V6'']].
 
Narrow angle [[V6|V6]] engines are very compact but suffer from vibration. Lancia's [[1924]] engine was such a design; Lancia produced similar engines until the [[1970s]]. More recently, [[Volkswagen]] have used such a design, known as the [[VR6 engine]]. In this engine, both banks share the same cylinder head and are extremely close together.
 
Other notable [[V6|V6]] bank angles:
* The 10.6° and 15° [[Volkswagen]] VR6, a [[V6|V6]] with such a narrow angle it shares many characteristics with the [[straight-6]], such as its firing order and use of a single cylinder head.
* The 54° [[GM 54-Degree V6 engine|GM/Opel V6]], designed to be narrower than normal for use in small [[front-wheel drive]] cars.
* The 65° [[Ferrari Dino]] [[V6|V6]]. The engine was originally fed by [[carburetor]]s. A 60° angle was limiting the size of the carburetors, while a 65° angle allowed to mount larger carburetors to the expense of a slight increase of vibrations.
 
==Odd and even firing==
Many [[V6|V6]] engines have been based on [[V8 engine]] designs. One characteristic of these engines is a notorious ''odd-firing'' behavior.
 
Purpose-built [[V6|V6]] engines use one crankpin per cylinder for a smooth ignition 120° ignition pattern. In contrast, most V8 engines share a common crankpin between opposite cylinders in each bank. That is, the [[crankshaft]] has just four pins for [[V8|eight cylinders]], and a cylinder fires every 90° for smooth operation.
 
[[V6|V6]] engines that are converted from V8 engines often have three shared crankpins arranged at 120° from each other, similar to an [[Straight-3|inline 3-cylinder]] with two pistons per crankpin. If the cylinder banks are arranged at 90° (as they commonly are in V8-derived V6s), this leads to a firing pattern with groups of two cylinders separated by 90° of rotation, and groups separated by 150° of rotation.
 
An example is the [[Buick V6 engine#231|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:
 
Nissan use the firing order  1-2-3-4-5-6 in some of the [[V6|V6]] engines they make
 
<div align=center>
{| width=90%
|- align=left
|width=12%|'''Angle'''
|colspan=9 width=11%|0°
|colspan=9 width=11%|90°
|colspan=9 width=11%|180°
|colspan=9 width=11%|270°
|colspan=9 width=11%|360°
|colspan=9 width=11%|450°
|colspan=9 width=11%|540°
|colspan=9 width=11%|630°
|- align=left
|'''Odd firing'''
|colspan=9 width=11%|1
|colspan=15 width=18%|6
|colspan=9 width=11%|5
|colspan=15 width=18%|4
|colspan=9 width=11%|3
|colspan=15 width=18%|2
|-
|'''Even firing'''
|colspan=12 width=14%|1
|colspan=12 width=14%|6
|colspan=12 width=14%|5
|colspan=12 width=14%|4
|colspan=12 width=14%|3
|colspan=12 width=14%|2
|}
</div>
 
In [[1977]], [[General Motors Corporation|General Motors]] introduced a unique "split-pin crankshaft" in the [[GM 3800 engine]]. Using a crankpin that is 'split' and offset by 30° of rotation results in smooth, even firing. Such a 'split' crankpin is weaker than a straight one, but modern materials and manufacturing produce a crankshaft that is strong enough. In [[1986]] the similarly-designed 90° [[PRV engine]] adopted the same 30° crankshaft offset design to even out its firing.
 
==Racing use==
[[The [[V6|V6]] engine was introduced into racing by Lancia with the Aurelia B20 in 1951. Lancia went on to develop the D23 and D24 racing cars which competed with great sucess up to 1955 when the Lancia racing operation was taken over by Ferrari. Vittorio Jano who had designed the Lancia V6 went over to Ferrari at this time and went on to develop the Ferrari Dino [[V6|V6]]. [[Alfredino Ferrari|Alfredo Ferrari]] (nicknamed Dino),]] the only legitimate son of [[Enzo Ferrari]], suggested to him the development of a 1.5&nbsp;L [[DOHC]] [[V6|V6]] engine for F2 at the end of [[1955]]. Soon afterwards, Alfredo fell ill, suffering from [[muscular dystrophy]]. While in hospital, he discussed technical details with the engineer [[Vittorio Jano]]. Dino would never see the engine; he died on [[1956-06-30]] at the age of 24.
 
The Dino [[V6|V6]] underwent several evolutions, and—with an increased [[engine displacement]]—competed in the 2.5&nbsp;L [[Formula One]].
 
Until the advent of wing cars, a wide 120° bank angle was appealing for racing engine designers as it permits a low [[center of gravity]]. It was 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. A further evolution of the [[Ferrari]] Dino built for new Formula One 1.5&nbsp;L regulations engines had this configuration.
 
This 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&nbsp;L [[V6|V6]] with an aluminum block but was replaced in [[1969]] by a 2.4&nbsp;L 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 became the most successful car in [[Rally racing]] history.
 
Another influential [[V6|V6]] design was the [[Renault]]-[[Gordini]] CH1 [[V6|V6]], designed by [[François Castaing]] and [[Jean-Pierre Boudy]], and introduced in [[1973]] in the [[Alpine (car)|Alpine]]-Renault A440. The CH1 was a 90° [[cast iron]] block [[V6|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|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&nbsp;L prototype championship in [[1974]] and several European Formula 2 titles. This engine was further developed in a tubocharged 2&nbsp;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&nbsp;L to power the Formula One Renault RS01. Despite frequent breakdowns that resulted in the nickname of the 'Little Yellow Teapot', the 1.5&nbsp;L finally saw good results in 1979.
 
Ferrari followed Renault in the [[Turbo Engine|turbo]] revolution by introducing a [[Turbo Engine|turbocharged]] derivative of the Dino design (a 1.5&nbsp;L 120° [[V6|V6]]) with the Ferrari 126.
 
Both Renault and Ferrari failed in their attempt to win the Drivers's Championship with [[V6|V6]] [[Turbo Engine|Turbo]] engine. The first [[Turbo Engine|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|V6]] (designed by [[Porsche]]) and the [[Honda]] [[V6|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.
 
==External links==
* [http://home.off-road.com/~merls_garage/oddfire.html Understanding the odd-fire [[V6|V6]]]
 
[[Category:Technology]]

Latest revision as of 11:37, 29 October 2008

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