Jay Honeck wrote:
So, I've seen scads of real-life experience that says that shock cooling
is just not real. The real part is people who don't practice engine-out
landings and then crumple an airplane botching the real thing.

I don't believe shock cooling exists, either. Or, if it does, it's
fairly insignificant.

But I do believe that repeated and sudden applications of full power
are harder on an engine than steady-state operation. Touch & goes
and engine out practice require this type of engine operation.

Engines have vibration and resonances that vary with RPM. Running at a
constant RPM for long periods of time causes a certain wear pattern on
certain parts. Varying RPM over time induces different vibration an
part resonances and spreads the wear over different areas. This isn't a
bad, bad, bad thing.

Matt