Well think about the application.
What are the engines powering? A spaceship? A boat? A giant train?
Perhaps each of those applications will have different engine variants. Nuclear, electric, steam, diesel, gasoline, fission....
An engine room needs an engine, fuel supply, control equipment, maybe maintenance equipment, some sort of cooling system... It needs a power output either via cables (like a generator) flywheel or spinning shaft (rotational/mechanical)
Then you need entrances and exits for personnel, maintenance access areas, regular lighting, emergency lighting, alarm lighting....
Picture the room and it's purpose, then give every detail in the room a purpose.