M wrote:

If you have seen the BSFC numbers of the latest and greatest
automobile gasoline engines, they're really not better than a
IO-520. Why? because it's a lot easier to optimize a gasoline
engine for fuel efficiency when it's operated at a narrow RPM range
with little power variation. Automobile engines achieve good fuel
efficiency through electronic engine control only because it's much
harder to gain good efficiency across a much wider RPM range and
throttle setting. From a thermo efficiency point of view, the
gasoline aircraft engines designed in the 50s are very good, if
they're leaned properly (which can be easily done with good fuel
injection and EGT instrumentation), I doubt they can get much better
in fuel efficiency regardless of what electronic you put on them.


Yes, well aircraft engines have a similar problem in terms of
altitude (I know, you have a mixture control) but was also thinking
beyond just the electronics and the methods of injection to
thinhs like pistons, combustion chambers and cams. Those things
have been addressed on most other engines.

But it really doesn't matter because everyone is moving toward
kerosene regardless. Its just one of the several products (as is
gasoline) of the refining process of crude oil.