For the best answers, search on this site shorturl.im/axJbT It's just been pressed down on for so long. :) Orrr. Water? Like the effect of water on paper. :D ]
When it works right it lets cooler air into the intake system, but that is heated any way in the intake manifold to help atomization and vaporization or the fuel. When it works wrong the filter gets wet and refuses to let air through the filter starving the cylinders for air resulting in poor performance.
It is an intake that takes air from in front of the radiator so it has not been heated by the hot coolant running through it. In some cases they even have compressed gasses like freon running through pipes coiled around them. The point is the make the air denser so more air ends up in the engine cylinder, leading to better combustion and more power.
