It's typically not problems with the engine itself,
Oh yes it is. This new type auto based engine must operate at 85-100% of it's maximum rated power for it's entire life cycle at a very high RPM, which causes accelerated engine wear. Auto engines are not so designed, and hence cannot do this. An example of this is the Bathurst 12 hour race for the "showroom" class. A good many of these cars have engines fail.
but with changes or systems that have to be designed to install it in an aircraft:
- A custom cooling system, to provide enough cooling without excess drag
- A system to turn the propeller at an appropriate speed, without transmitting vibrations to the engine that it is not designed to handle
All this adds weight and service complexity compared to existing aero engines.
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Perhaps, you put a different ignition system on to give you redundancy
- Perhaps, the oil system (sump) is not designed to work in the range of attitudes encountered in an aircraft.
- You probably have to fit all this in a space designed for some other type of engine
All these "perhaps" mean large development costs, and a high sale price to recoup investment over a very small market.
I don't agree that aircraft engines are superior technology to auto engines.
You got that right. Aero engines are Jurassic. However, like it or not...what we have is going to be around with no alternative while fossil fuels are the power source. The reasons for this are weight and cost of any new development. Don't get me wrong... I would love to be able to buy a new technology engine that costs about the same, has the same horsepower, same weight, and less fuel flow. Sadly.. ain't gonna happen