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how do CHT's and OAT correlate?

KayS

Well Known Member
Hey All, how do CHT's and OAT correspond to each other? Background is that i try to figure out if the drop of CHT recently was caused by cylinder break in or just because it was colder. For sure CHT decreases when outside temps are lower, but is there any nice formular to quantify this? Something like delta-OAT = Pi * delta-CHT or so?
Cheers
Kay
 
OMG, :eek: you are giving me nightmares about my Heat and Mass Transfer class from 40 years ago. Forced convection ain't simple. Do us a favor and just fly, look at the gages over your years with the new bird and recognize the OAT changes with your surroundings. It's not just temperature for instance. Less dense air at altitude can cause higher CHTs. I saw that in a flight from Texas to Vegas some years ago.

Edit.... There are times that it seems to be a 1 to 1 correlation. COLD dense air can really drop the CHTs. I imagine the folks that live in colder climates see it more than I do. Coldest for me has been 7 F OAT and the CHTs were down 50 ish from memory.
 
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I believe that there are too many variables involved to make this practical to figure out.
 
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Ok, seems that the topic is (as usual) more complex than expected. I will just fly and try to compare the CHT's that appeared in similar conditions. that should be enough to assess the brake in process.

though i think the question is still interesting from an scientific point of view. maybe somebody could add some light with engineering data for education.

Thanks for the inputs.

Kay
 
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