Mailing List lml@lancaironline.net Message #32858
From: <MikeEasley@aol.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: What Should My CHTs and Oil Temps Be?
Date: Mon, 14 Nov 2005 15:23:50 -0500
To: <lml@lancaironline.net>
I've read all the GAMI stuff and think I understand pretty well the relationship between mixture and CHT's, EGT's, fuel flow, etc.  Here's more information.  Since I was at around 60% power, I ran 50 ROP which should be fine and my temperatures were within limits.  Those CHTs are OK to run all day with from what I understand.
 
So Walter, the real question is...
 
Is 205 on the oil temp abnormally high for those CHT's?
 
Should 375 on the CHT's correlate with 190 on the oil temp, instead of 205?
 
At that power setting, mixture, OAT, should "normal" be closer to 350 CHT, 185 oil temp?
 
If both are high, then I increase the air flow, in my case the exit size.
 
If the CHT's are fine, but the oil temp is 20 degrees too hot, start troubleshooting the oil cooler, vernatherm, etc.
 
Scott, the numbers from Continental include a very wide range in the "normal" category.  I've got about 70 hours on my engine.  It was fine during the test flight hours, about 185 oil temp, but shot up after that.  If oil temps redline at 240, I don't necessarily want to cruise all day at 235.  Same with the CHT's, that's the reason for the question.  If I put in larger exit tunnels, I can bring down the CHT's but do I need to?  If I want to "fine tune" my temps, what should be my target. 
 
If somebody could give me a target like:
 
75% power, 100 ROP, 7,500 feet, standard temp, I should have 370 CHT, 190 oil temp.
65% power, 100 ROP, 9,500 feet, standard temp, should have 360 CHT, 180 oil temp.
 
There has been an epidemic of ES's with normal everything, but high oil temps in the 210 degree range, replaced oil coolers, replaced vernatherms, etc.  I'm trying to determine if I suffer from the same illness or whether I just need to move more air through my cowl.
 
I know I can reduce CHT's with some more air, or a richer mixture.  But my real issue is, come next summer, I don't want to have to climb out at 140 KIAS, a measly 500 FPM, to keep my oil temps down, same with CHTs.
 
Thanks for helping me tackle my problem.
 
Mike
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