* Exhaust gases are hotter and more dense than intake gases. This means that they exert more pressure on the valve, so a smaller valve is needed to withstand the force.
* The exhaust valve opens and closes more frequently than the inlet valve. This is because the exhaust stroke of an engine is shorter than the intake stroke, so the valve needs to open and close more quickly to allow the gases to flow through. A smaller valve is lighter and can move more quickly than a larger valve.
* The exhaust valve is located closer to the combustion chamber. This means that it is exposed to higher temperatures than the inlet valve, so it needs to be made of a material that can withstand the heat. A smaller valve can be made of a more heat-resistant material than a larger valve.
In general, the exhaust valve is about 10-15% smaller than the inlet valve. This difference in size helps to ensure that the engine operates efficiently and reliably.
