I have a Mix material set up to transition from the solid copper appearance, which is how the engines look when they are off, to the glowy, spinny appearance for when they are powered up.
I'll give you a tip about the copper texture, one that applies equally well to any kind of bare metal: Don't make the highlights pure white. Metals are unique in that their highlights and reflections are tinted the same color as the metal. That's something I never understood until relatively recently and it makes a world of difference.
Oh, and if you're using Max 8 or later, I strongly recommend giving Mental Ray a try. It takes some getting used to, but it's a whole quantum level beyond the scanline renderer in terms of quality and
speed. 