manifold pressure
That is a good answer, but not the correct one! When, in instrument conditions or night time and limited visibility, your attention is going to be with the flight instruments, not your engine instruments. The correct answer is the "ball" in your turn and bank indicator! If there are any reduction in power in either engine, the ball will move towards that engine! Now if you had your "flight director" or autopilot engaged, it would correct for the yaw produced by the dead or dying engine, but not hold it in most cases. But even then, the ball would still show you which engine has died or dieing. Now we are only talking about aircraft in Aces High, not the latest Boeing or Air Bus product, whole different world there!
