Introduction:
If a cylinder and a multi-cylinder engine develop the same power, then it indicates that their stroke volumes (swept volumes) are also the same. For the same crank speed and the same piston stroke, the single cylinder engine has a larger cylinder bore.
Limitation of larger cylinder bore:
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Poor cooling of the cylinder walls.
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Increased vibrations and stresses.
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The weight of the piston in the single cylinder engine increases primary and secondary forces on the engine bearings. These forces are not balanced and cause vibrations.
Therefore the advantages of multi-cylinder engines are:
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Temperature stresses are reduced as the multi-cylinder engine has more cooling surface area due to smaller cylinder bore.
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The intensity of vibration is sufficiently reduced as the primary and secondary forces are balanced.
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More power strokes per revolution giving smooth torque output.
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Lighter flywheel allowing quicker acceleration
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Small valves and pistons enable cooling easier.
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More frequent and smaller pulsations make easier silencing.
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Engine is much more compact.
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Engine would weight much lesser than the single-cylinder engine.
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Easy to balance.
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Could be run at much higher speed.
