I am confused turbogus... so you haven't installed this yet, you are just trying to see if the PM 102 is more powerful than your stock one? Well your test may not be a good one because there are way to many variables involved, like you don't have it attached to the fan, the switch for the motor on our Cj's have variable speed settings which your test doesn't sound like it does, tying it directly to a battery on your van is not how the motor is set up if it where to be installed, etc. etc.
I waited to see if anyone else would respond but the only thing I can offer as advice is to do exactly what I did. Buy the 655-1039 Premium blower motor from NAPA, buy a new heater core, make a larger hole in the firewall for the motor, remove the heater assembly, disassemble it and remove the old parts and install the new ones, seal everything up on the heater box, reinstall it and you will experience some insane hot air blowing out like a hurricane. My blower motor is insanely more powerful than the stock one. I didn't get the PM 102 so all I can say is I am way more than impressed with the 655-1039 Premium blower motor from NAPA. It was $23 dollars so maybe instead of wasting all this time testing etc, just return the PM 102 and buy the one I got.
I just looked at your older post and I want to emphasize the diameter of my motor was larger than my stock motor even without the collar. What I did was remove the collar, enlarge the hole so that the new bigger 655-1039 motor could fit through and then re-installed the collar (per John Strenk's suggestion) after I installed the whole heater assembly. I will have to remember to slide the collar off if I ever need to remove the unit again, but it's not a big deal. Plus this saved time because I only had to enlarge the hole enough to fit the motor through not both the motor and collar. Hope this helps you out man.
Whenever something breaks on my Cj... I learn something new by fixing it.