Good grief
Jaguar Pilot, the goal posts keep moving! I thought that we were discussing jet engines.
My personal quick summary -
(1) Vmcg/Vmca for a normally aspirated piston engine aircraft will decrease with increasing Pressure Height,
(2) Vmcg/Vmca for a supercharged piston engine aircraft will increase with increasing Pressure Height up to full throttle height, and then decrease,
(3) Vmcg/Vmca for a Fully Rated (EGT Limited) Jet engine aircraft will decrease with increasing Pressure Height, and
(4) Vmcg/Vmca for a Flat Rated Jet engine aircraft will increase with increasing Pressure Height up to the height where temperature (EGT) becomes the prevailing limit, and then decrease.
Turbo-Props deliberately left out of the summary as you can play tricks with them (like injecting Water Methanol) to restore power loss with increasing Altitude and/or temperature.
It would have helped a lot if the original poster had been specific!
What's he/she studying, PPL, CPL, ATPL, Performance Engineering?
Regards,
Old Smokey