Vapor vortex is a myth, physically impossible.
The only solution I have found. Reduce the cap volume period. Most of the other is bull, as an Aero Eng and some knowledge in aerodynamics all that talk of vortex, turbulence, and passing the air past the coil multiple times, physically impossible. A couple of years ago we did wind tunnel tests by drawing smoke thru the cap air hole while having a vacuum on the mouth piece equivalent to a normal draw. No matter how we aimed the smoke using a needle, putting vanes in the cap, different positions of the air inlet, including under the coil. We used needles and slots of many shapes and sizes. Conclusion, we never got any rotation "vortex". Needless to say we used a transparent, cap. In aerodynamics you look at one molecule of air (vapor) and what it does. It enters thru the air hole with velocity but it is immediately effected by very strong draw (up) there is no way to keep it spinning around to pass by the coil multiple times.
