If you close the airflow, it will almost literally cut off ALL the air. This tank works perfectly as a MTL tank. Have you tried one? This Engine Nano is more MTL than any Kayfun...Alright. Technically you can mtl with the Nano. But let's face it, even if you close the airflow, it still is a really airy draw, because of the large chamber.
If you like it airy, fine. No pun intended.
But for a really tight ("classical" or cigarette-like) mtl-draw, there are so many better options for mtl than the Nano. And even after a couple of months, no tank ever reached the mtl-performance of the kayfun or some of its clones. At least in my opinion.