Originally Posted by EPOS
I'm not stating that the snorkel is for efficiency, as someone else was saying it was for cooling by sucking in the hot air to "cool" off the engine bay.
My point is diesel engines are by far more thermal efficient so sucking out hot air is not needed.
PR - I too have used a cone filter and have noticed noticeable lag once heat soaking has occurred (waiting for light to turn green).
The other person making the comment about removing the heat is a co-worker who used to develop components for BMW, Mercedes, VW. One of the things he designed in our car is the radiator fan which I thought was pretty cool. I just asked him his input on this topic as I saw an assortment of answers, and he threw his in too. The only person who truly knows why it is there would be the person who designed the air box snorkel assembly. We are all just guessing, but somewhere in our guesses, there must be one close to correct answer.