Is it possible that some areas of our cylinders are getting much warmer, or staying much cooler than the probe is reading?  I'm assuming that, in flight, that the cylinder temp is more even in all areas due to the increased air flow.  Could baffling (good or bad) send a high amount of air to where the probe is, not necessarily cooling the entire cylinder, and make your number look good on your monitor, but really be cooking your cylinder?

Mike,

 

I'm no engine guy BUT the cylinder heating is much more even on the ground since there is no air flow to speak of.  In flight there is much evidence that cylinders are unevenly cooled - i.e. take my cylinder #2 (Please!) - directing some airflow past the front flat spot, the bottom front 1/4 of the cylinder finally gets some cooling air, thus dropping the CHT by 15 degrees.  And, yes, before that the probe was over heated in this area.

 

The ADA cooling presentation showed how careful baffling can provide air to all the places the engine manufacturer expected air to be there.

 

The probe location (at least on Lycs) is not well finned and should be as hot as anywhere on a well baffled cylinder.

 

Now, after the cyl is malformed by unequal heating, think about those poor oil cooled pistons - hopefully the rings are taking up the differences.

 

Scott Krueger

Merely a 4-cly Lyc IO 320