Hi. I don't use Belini Patch, i use original gp3 1.13 physic file and performance for drivers (i mean 16328 as max) and engines (800 BHP).
I set the CC engine power usually at 10.000 and the CC grip in a range from 9.500 (as Cleveland or Toronto) to 13.000 (in many ovals the grip is over 12.000) just to have a very very very hard qualyfing lap (i mean i can get the pole, but i have to do a really perfect and aggressive lap).
But i think there is not a range which can be considered ok for all: it depends upon track, and your ability level (for me it is not the same in every circuit: there are circuit in which i feel very nice, and others where i am a disaster, i mean it depends also upon your feeling with the track, or with the particular setup you have to use for that circuit).
A good way could be: set the value at 10.000, test, test and again test the track, and then (only when you have a good feeling with the track) modify the value as you like or as you need.
Bye.