As an eight-cylinder is called reciprocating engines that have eight cylinders.
The eight-cylinder is mainly produced as a combustion engine. It can be designed as a gasoline or diesel engine. Today it is mostly built as a V engine. Become Rarely are boxer engines and, because of the length, in-line engines.
The eight-cylinder internal combustion engine is most commonly used as driving trucks, passenger cars of the upper class, as well as sports cars. In addition, he used to drive for rail vehicles, light aircraft ( boxer engines American type ), ships (as inline and V engine ) and as a stationary power plant engine.
In automotive engineering, the eight-cylinder engine is almost always water-cooled. Air-cooled models (eg Tatra ) were exceptions. Eight-cylinder in-line engines have especially as gasoline engines, excellent smoothness, since the free mass forces first and second order are as already balanced the six-cylinder in-line engine. In addition, the firing intervals are reduced. Have crankshafts of series motors, however, because of their length and problems with torsional vibrations of the torque to be transmitted. In the automotive eight-cylinder in-line engines were therefore made only in the 1920s and 1930s for luxury vehicles and made usually less than 200 hp (147 kW).
The usual form of V8 engines is the so-called cross -plane V8 with a cranked at 90 degrees of crankshaft. He has with appropriate counterweights on the crankshaft a perfect balancing of free mass forces and moments of first and second order. Although the firing interval is uniform as a whole, but not within a cylinder bank. In conjunction with a double-flow exhaust system (right and left cylinder bank each have an independent system ) this leads to the " sonorous " and " babbling " sound of the typical V8 engines of U.S. manufacturers, but also modern German V8 engines. The cross -plane V8 is not suitable as a typical " cruiser motor " very quiet running at high speeds.
Rare is mainly in high -performance sports car (Ferrari F430, Lotus Esprit V8) used flat plane V8 with a 180 degree crank crankshaft. The firing order within a cylinder bank is regularly of a four- cylinder engine, there are smaller counterweights on the crankshaft as in Crossplane engines required and high speeds can be achieved. The smoothness is less fortunate, because mass second-order forces occur.
Each forged V- eight-cylinder crankshaft is in the forging process initially "flat"; the cross -plane design with 90 degree offset crank pins created by a subsequent, complex twist process in which squeezed in another die apparatus two of the four V- offsets from the forge level at forging heat or twisted. A cross -plane crankshaft is therefore more expensive to produce, if it is not cast.