Here's my take on engine management...
Yes, you would have to set the proper RPM, boost, mixture, and maybe prop pitch to get the most from your plane in each phase of flight.
BUT, in practice, this was probably not that big a chore, i.e. a trained pilot simply set his engine for takeoff, or cruise, or combat in a second or two and off he went. I doubt that a guy tinkered much with his engine in a fight, for example, until he got damaged or found out he was out of gas.
It WOULD add to the realism, at the expense of new guys not understanding and always having their engine set up wrong (unless you want to add "easy engine" as a setting, with a corresponding performance hit, like "easy flight" in WB).
What I'd suggest as a compromise, is make, say, 3 or 4 engine "performance profiles," i.e. Takeoff, Combat, Cruise, and Max range. Just use a keypress for each, and it's assumed you've set the appropriate controls for that condition, and your engine performs slightly differently in terms of thrust, fuel consumption, durability, etc, for each setting. If you get jumped in the climb, and forget to select "Combat," you'll be at a disadvantage, but you won't need to learn the specific inches of boost, prop setting, etc for every airplane in every condition.
Some specific controls MIGHT be worth adding, like oil cooler flaps and fuel shutoff, so you can manage your wounded bird and maybe survive instead of just blowing up if you don't shut down the engine. Airplanes that had automatic functions like the FW-190 wouldn't need to set the "engine condition."
Sort of a compromise between micromanaging everything and not having to do it at all
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