8/17/2019 About the smoothness of engines

1/2

 

The BMW 8-

series 

About the smoothness of engines

The number of cylinders is not the primary reason for engine smoothness, another important factor isthe way the engine is constructed, if it's an inline-, V- or boxer-engine. Those concepts will be

discussed here.

The Inline-Six Engine (or Inline-12)

As you can see an inline six engine consists basically of two mirrored three cylinder engines. That

results in two sorts of vibrations (around cylinder #2 and #5) which cancel themselves. So there isn'teven end-to-end vibration.

Because the crankshaft is identical to the one of a three cylinder, only twice as long and with twice as

much pistons, here as well is no change of the center of gravity and no forces are generated, neither

horizontal nor vertical ones. That is the reason why inline six cylinder engines run so smoothly.

The crankshaft of an inline six engine. Frontal view of crankshaft.

The V12 Engine

The V12 is said to be the most sophisticated engine design, being free of vibrations and running

smoothly. But so does an inline six. Now what is the difference between those two conceptsconcerning smoothness, as even the crankshafts look alike?

Let us return to the one-cylinder. It was said there, that an engine's power delivery occurs in 'jerks',

every time a combustion takes place. And that is the secret of a V12: the smoothness is increased bymore combustions per crankshaft revolution.

8/17/2019 About the smoothness of engines

2/2

 The crankshaft of a V12 engine. Frontal view of crankshaft.