Originally Posted by Vreimann
If it were only about motor thermal efficiency, the dual stage intake snorkel would be directed to pull air from the same location that the main air filter feed air comes from. Compressing hot air is not how thermal efficiency is achieved as for every BTU you add from compressing the hot air, you need to remove it to a degree to achieve your combustion goals. Lowering charge temperatures are important.
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).