Well, this is the first flowbench I've built for my own use at home. I have a constraint in that I'm limited with power supply. This restricts me to four motors which I can then run off two 13amp 240v plug sockets.
I started by collecting a bunch of old vacuum cleaners from friends and family. I ended up with six in total which I stripped down and removed the motors and wiring (to reuse in the bench). I also collected some 6" deck plates, 110mm soil pipe caps, a dwyer gauge that reads up to 30" H2O and a few other bit's and pieces.
After some crude testing to see how well they "sucked" I decided to use the four YDK units. These were also the newest of the bunch. Two of them were YV-2200s, one was the same wattage as the YV-2200 (probably an older version?) and the other was a slightly lower wattage motor. With these details in mind I used my spreadsheet for the YV-2200 motor flow curve and set the bench efficiency to a low 50% to see what the flow bench capacity is at 28" and 25" test pressures.
The flow capacity seems about right for the four cylinder heads that I normally work on.