Here is an interesting article about the new motors that Drainvac is using in their central vacuum units. I have a few of their current models and the motors are very good, I would say just as good if not better than Ametek. Apparently all of Domel's new motors are 5.7 inch so I have no idea how they get this much power. Some are more powerful than Ametek's 7.2 or 8.4 inch motor, that defies the law of physics, an 8.4 inch motor will move more air than a 5.7 inch motor. Anyway, the article is interesting.
Mike
https://www.thinkvacuums.com/topsecret
Mike
https://www.thinkvacuums.com/topsecret