A V engine, sometimes called a Vee engine, is a common configuration for internal combustion engines. It consists of two cylinder banks—usually with the same number of cylinders in each bank—connected to a common crankshaft. These cylinder banks are arranged at an angle to each other, so that the banks form a "V" shape when viewed from the front of the engine.
V engines typically have a shorter length than equivalent inline engines, however the trade-off is a larger width. V6, V8 and V12 engines are the most common layout for automobile engines with six, eight or twelve cylinders respectively.
The first V engine, a two-cylinder V-twin, was designed by Wilhelm Maybach and used in the 1889 Daimler Stahlradwagen automobile.
The first V8 engine was produced in 1903, in the form of the Antoinette engine designed by Léon Levavasseur for racing boats and airplanes.The first V12 engine was produced the following year by Putney Motor Works in London, again for use in racing boats. The first V6 engine to reach production appeared soon after in 1908, by the Deutz Gasmotoren Fabrik in Germany for use as a generator for gasoline-electric railway engines. However, it was not until 1950 that the V6 engine was used in series production automobiles, with the first example being the Lancia V6 engine. This V6 engine used a 60-degree V angle and separate crankpins for each cylinder, to reduce the vibration issues experienced by earlier attempts at production V6 engines.
Compared with an equivalent inline engine (the most common configuration for engines with less than six cylinders), a V engine has a shorter length but is wider. This effect increases with the number of cylinders in the engine; the length difference between a V-twin and straight-twin engines might be insignificant, however V8 engines have a significantly smaller length than straight engines.Compared with the less common flat engine, a V engine is narrower, taller and has a higher center of mass.
The "V-angle" (or "included angle") between the cylinder banks varies significantly between engines. Some engines have used a V-angle of 180 degrees (the same angle as a flat engine), such as several Ferrari V12 engines.At the other end of the scale, the 1922-1976 Lancia V4 engine and the 1991–present Volkswagen VR6 engine use V-angles as small as 10 degrees, along with a single cylinder head used by both banks of cylinders.
The engine balance of a V12 engines is that of perfect primary and secondary balance. For V engines with fewer cylinders, the engine balance will depend on factors such as the firing interval, crankshaft counterweights and whether balancer shafts are present.
The crankpins on a V engine are usually shared by two cylinders from opposing banks, with an offset between the two cylinders. Alternative configurations are separate crankpins per cylinder (such as several V-twin engines) or articulated connecting rods (for example, the such as the Rolls-Royce Merlin aero engine).
Some airplanes of the 1920s and 1930s used inverted engines, whereby the crankshaft is located at the top of the engine and the cylinder heads are at the bottom. Advantages include better visibility in a single-engined airplane, a higher thrust line, and resultant increased ground clearance for the propeller. Examples include the 1928 Argus As 10 V8 engine and the 1935 Daimler-Benz DB 601 V12 engines.
It is common practice for V engines to be described with "V#" notation, where # represents the number of cylinders. Configurations of V engines which have reached production are as follows:
A V-twin engine, also called a V2 engine, is a two-cylinder piston engine where the cylinders share a common crankshaft and are arranged in a V configuration.
A V6 engine is a six-cylinder piston engine where the cylinders share a common crankshaft and are arranged in a V configuration.
Piston engines are usually arranged so that the cylinders are in lines parallel to the crankshaft. Where they are in a single line, this is referred to as a straight engine.
The straight or inline engine is an internal combustion engine with all cylinders aligned in one row and having no offset. Usually found in four, six and eight cylinder configurations, they have been used in automobiles, locomotives and aircraft, although the term in-line has a broader meaning when applied to aircraft engines, see Inline engine (aviation).
A V4 engine is a four-cylinder piston engine where the cylinders share a common crankshaft and are arranged in a V configuration.
The engine configuration describes the fundamental operating principles by which internal combustion engines are categorized.
A flat engine, also known as a horizontally opposed engine, is a piston engine where the cylinders are located on either side of a central crankshaft. It is effectively a V engine with a 180-degree angle between the cylinder banks. A flat engine should not be confused with the opposed-piston engine, in which each cylinder has two pistons sharing a central combustion chamber.
A flat-four engine, also known as a horizontally opposed-four engine, is a four-cylinder piston engine with two banks of cylinders lying on opposite sides of a common crankshaft. The most common type of flat-four engine is the boxer-four engine, each pair of opposed cylinders moves inwards and outwards at the same time.
A straight-twin engine, also known as an inline-twin, vertical-twin, or parallel-twin is a two-cylinder piston engine where two cylinders are arranged in a line along a common crankshaft.
A straight-four engine is a four-cylinder piston engine where cylinders are arranged in a line along a common crankshaft.
The straight-five engine or inline-five engine is an internal combustion engine with five cylinders aligned in one row or plane, sharing a single engine block and crankcase. The justification for a five cylinder engine is that it is almost as compact as an inline-four, and almost as smooth as a straight-six engine.
Balance shafts are used in piston engines to reduce vibration by cancelling out unbalanced dynamic forces. The counter balance shafts have eccentric weights and rotate in opposite direction to each other, which generates a net vertical force.
A transverse engine is an engine mounted in a vehicle so that the engine's crankshaft axis is perpendicular to the direction of travel. Many modern front-wheel drive vehicles use this engine mounting configuration. Most rear-wheel drive vehicles use a longitudinal engine configuration, where the engine's crankshaft axis is parallel with the direction of travel, except for some rear-mid engine vehicles, which use a transverse engine and transaxle mounted in the rear instead of the front. Despite typically being used in light vehicles, it is not restricted to such designs and has also been used on armoured fighting vehicles to save interior space.
A motorcycle engine is an engine that powers a motorcycle. Motorcycle engines are typically two-stroke or four-stroke internal combustion engines, but other engine types, such as Wankels and electric motors, have been used.
Engine balance refers to how the forces are balanced within an internal combustion engine or steam engine. The most commonly used terms are primary balance and secondary balance. Unbalanced forces within the engine can lead to vibrations.
The crossplane or cross-plane is a crankshaft design for piston engines with a 90° angle between the crank throws. The crossplane crankshaft is the most popular configuration used in V8 road cars.
A crankpin is a mechanical device in an engine which connects the crankshaft to the connecting rod for each cylinder. It has a cylindrical surface, to allow the crankpin to rotate relative to the "big end" of the connecting rod.
A flat-eight engine, also known as a horizontally opposed-eight, is an eight-cylinder piston engine with four cylinders on each side of a central crankshaft.
A V8 engine is an eight-cylinder piston engine in which the cylinders share a common crankshaft and are arranged in a V configuration.
A big bang engine is an unconventional motorcycle engine designed so that most of the power strokes occur simultaneously or in close succession. This is achieved by changing the ignition timing, changing or re-timing the camshaft, and sometimes in combination with a change in crankpin angle. The goal is to change the power delivery characteristics of the engine. A regular firing multi-cylinder engine fires at approximately even intervals, giving a smooth-running engine. Because a big-bang engine has uneven power delivery, they tend to run rougher and generate more vibration than an even-firing engine.