Maximum value of sdf <maxRotVelocity> parameter

Hello everyone.
I am trying to modify the iris.sdf to make it heavier. I know there are similar issues about this topic but no one answers my question. I want to make it heavier and fly it (in SITL) in an environment with less density. According to my calculations, the drone requires for hovering (with a motor constant of 2.5e-06) 3000 rpm per rotor, but the maximum achievable value of seems to be near 830 rpm.
I have reached the same conclusion in different ways, by increasing the gravity acceleration until the drone can’t even take off, and by taking the to higher values.

Does anybody know how to change this limit?