These so-called high-efficiency motors are also known as coreless motors. Here is a link to the technical differences between a normal and corless motor:
http://www.solarbotics.net/starting/200111_dcmotor/200111_dcmotor2.html
As mentioned in this link, coreless motors can easily overheat, especially if used with a DC power pack that has "pulse power."
There have been a few messages on these forums in the past by members who burned up some very expensive coreless motors because their power packs were pulse power types.
Easy answer. Do a Google search for each one. I have done that. There is plenty of info out there. Store the links that you like in Favorites.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Frecuently I heard about "high efficient motors", specially from Europe, such as Faulhaber, Postescap, Maxxon, etc. Anybody knows something about that expensive motors? Thanks.