Why the inlet valve diametre is more than exhaust valve diametrer?

Replies

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  Ramani Aswath

  The inlet mitral valve to the main pumping chamber of the heart is larger than the outlet aortic valve. This is because the pressure drop across the inlet valve is low as the heart dilates, while that across the aortic valve is high.
  
  Likewise in the IC engine.
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  Siddhant Mukherjee

  When an engine aspires, the piston is lowering and continuously incresing the volume of the system hence decreasing pressure. A larger diameter at inlet will ensure greater static pressure at inlet and thus it will facilitate the rush of charge into the system. Whereas, during exhaust the system's pressure is too high so, the static pressure at exhaust valve must be low so as to get rid of exhaust gas as quickly as possible to prevent exhaust blowdown. For reducing the static pressure at the exhaust valve, it is made smaller in dia.
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  Sarathkumar Chandrasekaran

  i want to add one more point to @#-Link-Snipped-# answer.small exhaust valve would help in having a reduced backpressure which play a important role in attaining high efficiency .At the same time note that a optimum backpressure is also necessary for increased efficiency to re burn unburnt gases.At the end of exhaust stroke high pressure builted in combustion chamber and assist pushing gases out of chamber.
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  Sarathkumar Chandrasekaran

  i want to add one more point to @ S.mukherjee answer.small exhaust valve would help in having a reduced backpressure which play a important role in attaining high efficiency .At the same time note that a optimum backpressure is also necessary for increased efficiency to re burn unburnt gases.At the end of exhaust stroke high pressure builted in combustion chamber and assist pushing gases out of chamber.