Scudrunners

i have heard about it but to be honnest my own limited experience operating an AEIO-360 200hp for 1100 hours of acro has been that my two overhauls were due to lack of use (cam rust ) and then cracks in the engine case. I have never experienced any cylinder head issues .. Yet and I literally takeoff and stay near full power except for spins and then chop power to land. So I guess im very hard on the cylinders .. Perhaps thatll be my next engine problem :)


Unless shock cooling can also damage the case? But i always thought the case damage is vibration /gyroscopic related?

To be fair, both the Lycoming parallel valve
and angle valve heads are spectacularly
resistant to cracking.

A better question:  why do cylinder heads crack?

Answer #1) CHT's over 400F
Answer #2) full rich mixture in descent from cruise

If people avoid both of the following, their
cylinder head cracking problems will drastically
decrease or disappear entirely.

It's too bad that people get all caught up in the
words, as Frank Zappa once observed.

It is a fact that cylinder heads crack.

This is not a good thing.

It is worthwhile learning what cracks cylinder
heads, and to not do that.  Mike Busch has
some thoughts on this.

yeah, i've read all hist stuff.. very good advice. I never see anywhere close to 400F .. even on a hot day after 45 minutes of acro full power. CHT's go to about 350F and Oil temps get to 210F or so under those conditions but I guess the pressure cowling and baffle sealing which I pay good attention to keeping in good shape work very well.

[quote]I never see anywhere close to 400F[/quote]

Me neither!  Probably has a lot to do, with why we
don't see cylinder head cracking.

The hotter you run metal, the shorter it's life.

The funny thing is that I beat on all sorts of Lycomings
like they owe me money, and they have the best compressions
on the field at annual time.