BDS writes:

I'm not so sure about that - but I also don't really know. As you said,
these engines are fuel/air cooled, but as you ask for more power you also
produce more heat, and I suspect that the engine is actually less efficient
thermodynamically at full power than it is at reduced power. In other
words, as you approach full power you get increasingly more heat and less
actual BHP for that heat.

In general, the greater the temperature gradients in a heat engine,
the more efficient the engine becomes.

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