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V-Twin

 

V-Twin

This article is about the two-cylinder V engine. For the Soviet V-2 tank engine from World War II, see Kharkiv model V-2. For other uses, see V2 (disambiguation).

A V-twin engine, also called a V2 engine, is a two-cylinder internal combustion engine where the cylinders are arranged in a V configuration.

History

Gottlieb Daimler built a V-twin engine in 1889. It was used as a stationary powerplant and to power boats.[1] It was also used in Daimler's second automobile, the 1889 Stahlradwagen ("steel-wheeled car").[2] The engine was also manufactured under licence in France by Panhard et Levassor.[3]

In 1903, both Glenn Curtiss in the United States and NSU in Germany began building V-twin engines for use in their respective motorcycles.[4] Peugeot, which had used Panhard-built Daimler V-twins in its first cars,[3][5] made its own V-twin engines in the early 20th century. A Norton motorcycle powered by a Peugeot V-twin engine won the first Isle of Man Tourist Trophy twin-cylinder race in 1907.[5]

Configurations

Crankshaft configuration

Most V-twin engines have a single crankpin, which is shared by both connecting rods. The connecting rods may sit side-by-side with offset cylinders, or they may be "fork & blade" items with cylinders in the same plane without an offset.

Some notable exceptions include the Moto Guzzi 500cc (with 120° V angle and 180° crank pin offset) that Stanley Woods rode to win the 1935 Isle of Man TT;[6] the 1983 Honda Shadow 750, claimed as being the first V-twin with an offset-dual-pin crankshaft;[7] and the 1987 Suzuki VX 800, 45° V angle with 45° crank pin offset in USA and 75° crank pin offset for the rest of the world.[8]

V angles

Generally, any two-cylinder motorcycle engine with its two cylinders arranged more than 0° and less than 180° apart is referred to as a V-twin. Although Ducati use the name "L-twin" for their 90° twin engine (with its front cylinder nearly horizontal and the rear cylinder almost vertical), there is no technical distinction between V-twin and L-twin engines; and these are merely names used by convention.

A 90° V-twin will, with a correct counterweight, yield perfect primary balance,[9] although its firing intervals are uneven. A V-twin with an angle of less than 90° is more compact and has more even firing intervals, but has significantly poorer mechanical balance. Offset crankpins are sometimes used to reduce the resulting vibration.[9]

V angle Examples
20° Daimler engine used in 1889 Stahlrad motor car[2]
26° Matchless Silver Arrow
42° Indian Powerplus, Chief, Scout
45° Crocker Motorcycles
Harley-Davidson
Sokół 1000
Suzuki VX800, Boulevard C50, Boulevard C90, Boulevard S50, Boulevard S83
47.5° Vincent Rapide Series A
48° Yamaha MT-01, XV1600, XV1700
49° Indian Thunder Stroke 111, Chief, Chieftain [10]
50° AJS S3
BSA Model E, G14, Y13
Husqvarna Motorcycles
Brough Superior SS100 (JAP engine)
Kawasaki Vulcan 1500, 1600
Matchless Model X
Victory Motorcycles
Vincent Rapide Series B, C
52° Honda Shadow, Transalp, Deauville, XRV750 Africa Twin
Kawasaki Vulcan 1700 & 2000
54° Suzuki Boulevard C109R, Boulevard M50, Boulevard M90, Boulevard M109R
55° Kawasaki Vulcan 800, 900
56.25° S&S X-Wedge Engine
60° Britten V1000
Harley-Davidson VRSC
Highland Motorcycles
Aprilia RSV Mille, Tuono (Rotax engines)
Yamaha XV250, XVS250
70° Suzuki RGV250(VJ23)
Yamaha XVS650
72° Moto Morini 350, 500
1125R (Rotax engine)
Voxan
75° Hyosung GT250, GV250
KTM 1190 RC8
Yamaha TR1, Virago, XVS1100
77° Aprilia RXV/SXV
80° Honda CX series
Rotax 810, 660, 490
87° Moto Morini Corsaro 1200
90° Aprilia RS250, SL 750 Shiver, NA 850 Mana
Bimota V Due
Briggs & Stratton
Cagiva
Ducati
Folan 290
Gilera GP 800
Hesketh V1000
Honda VTR250, VTR1000, XL1000V, VT125 & XL125V Varadero
Hyosung GT650, GV650
Kawasaki Prairie 650, V-Force
Mazda
Moto Guzzi
Suzuki RGV250(VJ21&VJ22), SV650, SV1000, TL1000, V-Strom
120° 1934 Moto Guzzi 500cc
170° Zündapp KS 601

Orientations

The terms longitudinal engine and transverse engine are most often used to refer to the crankshaft orientation,[11][12] however, some sources, most prominently Moto Guzzi, use the terminology in the opposite way.

A Moto Guzzi Technical Services representative tried to explain to LA Times columnist Susan Carpenter that Moto Guzzi engines are "called 'transverse' because the engine is mounted with the crankshaft oriented front to back instead of left to right."[13] In spite of this, it is could be assumed that those who call V-twin motorcycle engines "transverse" when they are mounted with the crankshaft front-to-back and the cylinders sticking out the sides are saying that to them, the engine's axis is the line passing from one cylinder to the other, at a right angle to the crankshaft, rather than going by the crankshaft's axis.[14] Highly technical sources, such as V. Cossleter's Motorcycle Dynamics, or Gaetaeno Cocco's Motorcycle Design and Technology are careful not simply to use the terms "longitudinal engine" or "transverse engine," but rather to specify that they mark the engine's orientation based on the crankshaft, and so they will say "transverse crankshaft engine" or "longitudinal crankshaft engine",[11][15] or, conversely, "transversely mounted cylinders" in referenced to the classic BMW orientation, with a longitudinal crankshaft and cylinders at a right angle to the axis of the frame.[16]

Transverse crankshaft mounting

The engine can be mounted in transverse crankshaft position as on Harley-Davidsons, Ducatis and many recent Japanese motorcycles. This layout produces a twin cylinder motorcycle engine that is little or no wider than a single.[17] A narrower engine can be mounted lower in the frame with handling benefits. A significant disadvantage of this configuration for air-cooled engines is that the two cylinders receive different air-flows and cooling of the rear cylinder tends to be restricted.[18] Cooling problems are somewhat mitigated by having all "four" sides of each cylinder exposed to air flow. This differs from a parallel-twin cylinder engine which has a distinct front, back, and sides, but the inside of each cylinder is not exposed to airflow as the cylinders are typically joined together with a cam chain running up through the block in-between the cylinders.

Some transverse V-twins use a single carburettor in the middle of the V-angle to feed both cylinders. While this allows an economy of parts, it creates further cooling problems for the rear cylinder by placing its hot exhaust port and pipe at the back of the cylinder, out of the way or the air stream.

Longitudinal crankshaft mounting

The longitudinal crankshaft two-cylinder V as seen on Moto-Guzzis and some Hondas is less common. This orientation is suited to shaft drive, eliminating the need for a 90° bevel gear at the transmission end of the shaft. A longitudinal crankshaft engine fits neatly into a typical motorcycle frame, leaving ample room for the transmission, and cooling is facilitated by cylinder heads and exhausts protruding into the air stream.[19] Longitudinal crankshaft mounting is associated with a torque reaction that tends to twist the motorcycle to one side on sharp acceleration or when opening the throttle in neutral and in the opposite direction on sharp deceleration. Many modern motorcycle manufacturers correct for this effect by rotating flywheels or alternators in the opposite direction to that of the crankshaft.[20][21]

Automobile use

BSA made a V-twin car starting in 1921, then introduced a three-wheeler in 1929.[22]

V-twin engines, adapted from motorcycles, were featured in Morgan three-wheelers made from 1911 to 1939. A number of Morgan-inspired models are produced today including the Triking Cyclecar, which uses a Moto-Guzzi V-twin;[23] the Ace Cycle Car, which uses a V-twin Harley-Davidson engine;[24] and the JZR which uses engines from the Honda CX series.[25]

Mazda made 356 cc and 571 cc V-twins beginning in 1960 for the Mazda R360.[26][27]

Commercial use

Commercial equipment such as pressure washers, lawn and garden tractors, tillers, generators and water pumps use V-twin engines when that equipment is large enough to need more power, usually in excess of 16 horsepower, than can be provided by a single-cylinder engine. These V-twin engines have horizontal or vertical crankshafts, usually have 90-degree crankshaft angles, and are usually forced-air–cooled. The V-twin configuration gives these engines a smaller footprint and less vibration, in the absence of balancing shafts, than other two-cylinder configurations.

Manufacturers of such engines include Honda with its V-twin series engines;[28] Kawasaki with its FD, FH, FS, and FX series;[29] Subaru with its EH series;[30] Briggs & Stratton with its Professional and Intek V-twin Series;[31] Tecumseh with its OV691EA and TVT691 engines;[32] and Kohler.[33]

See also

References

External links

  • Detailed V Twin Engine Animations
de:V-Motor

es:Motor de dos cilindros en V

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