Originally Posted by Bill Simpson
With all due respect, what you're saying just hasn't been my experience.
ZC inserts, for example. When the wood is in the cut, covering the entire throat plate, how much more air is a wide plate going to provide vs. a ZC one? I posit not much more, if any. Widening your throat plate isn't really helping any airflow once there's wood covering it up.
As for 4" being the answer. Again, not in my experience. I have a simple 1.5hp Jet dust collector that has a 6" port that originally split into two 4" ports. They worked okay either alone or in tandem, but the real boost that _I_ have seen was when I went to 6" for as long as possible. I have about 35 feet of duct on my longest run with a couple elbows and it was miserable with 4" duct work. With 6", it will steal your cat, I promise! Granted, every dust collector is a little different and some don't respond to lowering the static pressure as well as others.
I don't think 4" is ideal most of the time. In fact, I'd say only stick to 4" if you're going to be pulling from a single machine and roll the DC around from one machine to another using a short length (6-8') of flexible hose. This is really not for a performance thing, but because 6" flex hose is expensive and kinda unwieldy.
My experience with 4 or 5 dust collector models (all of them 2hp and below) is that going to 6" is a very dramatic improvement in every case. I have not yet found one that worsens, provided the filters are good and clean. I'm not a fan of bags, either, and much prefer a Wynn Environmental canister filter upgrade on even the small 1hp models out there. The increased airflow is fantastic and will easily handle the added load of a larger duct.
Again, that's just my experience and I can't say I've seen everything, yet - but I'm workin on it!