As I said in post #23, rated power is an arbitrary number, based in large part on how long you need the engine to last at that power. Yes, you might have problems if you use the quoted power in an auto application as the rated power for an aircraft application - but again, that might be 4 times the power/capacity you get from a Lycoming. If you were developing an aircraft engine you would be more conservative in setting the power rating.
I see your point, however your "arbitrary" number will never be achieved at less than 2500 RPM, which is the requirement to eliminate the need for a weight adding reduction system. Auto based engines can never produce the required horsepower at such low rpm, and be of a small physical size and cubic capacity and be of caparable weight. So it's a given that some type of rpm reduction system must be incorporated, which means weight and something else that can potentially fail (Thielert gearboxes anyone?)
By your post quoted above, I think that you mean that an automotive engine capable of producing 500HP can be derated to reliably produce 300hp continuously?
For an example, I have just taken delivery of a new Mercedes Benz A45 AMG. Mercedes claim the engine in this vehicle to be the most powerful production 4 cylinder engine ever made. It produces 385hp from it's 2 litres with a large turobcharger producing 26psi of boost. It will propel the car to 100km/h in 4.6 sec and claimed fuel economy is 6.9l/100km. It is actually capable of producing 300hp at 2500rpm. So we can potentially use this engine without a gearbox.
It weighs 150kg dry compared to 218kg for your average IO550. With a cooling system and other necessary equipment, it could potentialy weigh less than the Continental. Would this Benz engine last 2000 hours? What fuel flow would you get? Would you be able to keep this engine cool at altitude? I'd rather you be the test pilot.
