Question

Carburetor is called lungs of petrol engine.why?

Answer 1

If it is called the lungs of an engine it is a really poor analogy. Lungs breathe in air. In a normally aspirated engine the piston area and stroke create the swept volume that sucks air into an engine…very much like lungs in animals. Carburettors restrict air flow with a throttle valve and add fuel to the air, They only let the engine breathe in fully when your foot is hard on the accelerator, so basically it is restricting breathing most of the time. That would be pretty much the opposite of lungs.