Denny, you're not giving motocalc enough credit here. Neither Motocalc nor Drive Calculator cares one bit about what the published performance claims for a motor are. Their results are based on an evolving and continuously updated database of actual tests. Now that we have data recording ESCs these programs will be even more accurate in the future.
Missed the word quadcopter in the first post. I was envisioning a four engined bomber or something.
No clue how I missed the obvious.
Okay, that means that even 8" pitch props are VERY marginal, developing 1700 some odd grams of thrust on a vehicle that will weight between 1500 and 2000 grams. Maybe the Supertigres really can't Hack it.....
Typically you have some higher KV motors in quadcopters to get more RPMs out of the smaller props. The faster you turn a motor, the more proper bearing support is important. Hacker motors have a bearing design that eliminates the possibility of the armature striking the magnets while rotating at 10k rpm. And they are much more efficient, turning your watts into torque instead of heat.
Remember, a quadcopter or helicopter has the glide angle of a buffalo turd. They're just smoking craters looking for a place to happen. Your primary goal has to be reliability.
I could care less if the motor in my Slow Stick takes a defecation break. I'll just fly in my preferred mode, gliding to a landing. My first love is sailplanes anyway!
If you lose a motor on the quadcopter, you are going to have a bad day. That's especially true on a heavy model such as you are contemplating. It looks to me that you're going to have to run the Supertigres pretty wide open just to get off the ground. At 65% to 70% efficiency, up to 35% of your watts are going to produce heat. Your quadcopter with SuperTigres will be a 400 watts times 35% equals a 140 watt heater! That's more than any soldering iron you'd use in wiring your plane. Your motors won't probably be enclosed, but they also don't have a lot of air moving past them. The inside part of a prop doesn't produce that much thrust. At the least you'll have to determine that you aren't melting down motors!