@Vortex, here are all the ship assets exported into a static scene. Pressing the V key toggles between ships and the spacebar toggles between the engine settings. You can see how I am building and managing the shaders there.
The method I am using for displacement is just a texture channel with directional noise multiplying by a value for displacement along Z. The amount of displacement is also modified by the V gradient of the UV coordinates of the mesh. This is the original mesh:
This is how the mesh is laid out in UV space. I oriented the mesh in UV space to take advantage of the UV coordinates so I could control the amount of displacement along the length of the flame. The vertices close to the engine get little to no displacement in Z and only a little wobble. The ones toward the end of the flame get the most displacement to make them appear to dance along Z.
You can see the displacement falloff in the wireframe below:
The texture itself is just a channel packed noise texture to mix color and displacement. There is a second mesh in the engine effect that has a swirling vortex shader on it just to add some extra dimension. Hopefully with everything isolated out like this you can better follow what I did.