I was flying along in my Mig-3 when some tool in a JU-88 put a few 8mm rounds into my motor. Instantly damaged! How rude! But I got to thinking...
Even though the engines in the game make noises telling you that they are damaged we don't get any real feedback. A 1200 horsepower motor with a blown piston, unbalanced crank or thrown rod is not going to run nice and smooth, it should probably shake the virtual fillings out of our virtual heads. In a similar manner we get airframe vibrations when gear/flaps are lowered when going too fast, would it be possible to apply that effect to engine damage and magnify it significantly?
I think it would go a long way for immersion. Imagine if you had to nurse a wounded bird home, but instead of a whimpering motor your airframe feels like its going to rattle apart!