I’d recommend checking out this thread: P1S: Chamber Fan Direction - #21 by richbo
It’s not specifically answering your question but the airflow can be improved significantly by removing the carbon filter. This was relevant for me as I printed a magnetic vent to attach a 3" hose which was directed to the outside. I was worried that the increased resistance was actually impeding outflow from the fan but now that the carbon filter is removed, I can feel a decent outward flow of air through a pretty long hose to the outside.