For this one ...
I used Alclad Stainless Steel for the base. Detailed it with gray and red, added som wiring painted red, and washed it with black. I intentionally left it pretty grimy looking.
This one ...
started with MM Stainless Steel and then got a heavy dose of flat black and some drybrushing with white and a touch of blue.
Best advice I can give is to search the net for photos of the engine you are doing and then try to match the photos. They are all different yet in many ways similar.
Heat does some strange things to the engine colors. Here is a photo I took last year of the right side exhaust on an F-15A . Note how the heat generated has given the parts all kinds of different colors.