If the engine forces are balanced like in a inline-6, why does the engine twist?
In: Engineering
Umm.. basic physics. If the part that spins accelerates its spinning (from a stop, or just picking up speed), then something – in this case, the rest of the engine – exerted that force upon it… and so since every action has an equal and opposite reaction, the main spinning part will apply a reverse spin force on the rest of the engine. That’s your twisting force. Big semi trucks starting from a stop really show this as the whole cabin seems to want to twist itself off its wheels.
Balanced forces in an engine are more intended to keep the engine from vibrating while spinning at a constant speed, since it contains parts that move up and down, not quite in sync with each other… as opposed to an inline 4 which, since it’s a 4-stroke engine, would have 2 cylinders moving up and 2 moving down simultaneously and in sync at all times. That’s much more naturally balanced. 6 cylinders aren’t so nicely staggered.
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