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In-flight CHTs

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teamgrumman(at)yahoo.com
Guest

Posted: Wed Sep 16, 2015 11:50 am Post subject: In-flight CHTs

Last Sunday my wife, Clytie, and I flew N626FT back to Auburn from Salt Lake City.  It has a fairly new engine;  less than 20 hours on it.  The engine is a tricked out engine from LyCon.  It also has a Power Flow Exhaust System.  



Getting to SLC was at full throttle and richened to keep the CHTs under 430 on an EDM 800.  We got terrible gas mileage.



Coming back, we went up to 12,500 feet (set the heading and altitude with an S-Tec 30) and I played with the mixture, throttle, and carb heat settings to see what I could get.  The interesting observation was that I could quite easily get the engine to run smooth lean-of-peak.  The odd thing was, at full throttle, it wouldn’t stay there. I can only think it had something to do with local temps and pressures.  



What I observed was: #1 & #2 were always the coldest (by about 10 to 20 degrees) and I never thought much of them.  Between #3 & #4, #3 was the first to go lean of peak and was very predictable. #4, however, would go lean, run smooth for a while, then it would richen enough to raise the CHTs.  I left the setting alone and just observed the outcome.  The CHT would go from 405 to 415 and back (plus or minus 10 degrees).  Then, occasionally, keep getting hot to 450 and then go lean again and the temp would go down; one time to as low as 397.  



If I leaned slightly more to keep #4 cooler, it would run OK for a while, go lean enough to run rough for a while.  I tried carb heat to see if it had any effect.  Minimal effect at best.



Then I tried pulling the power back to 50% (well, between 50% and 55%) and various lean settings.  The lean-of-peak setting was a lot more sensitive.  I aimed for a maximum CHT of 415.  As before, the engine would run great for a while and then the CHTs would move up or down for no apparent reason; i.e., no RPM change, no throttle, mixture, altitude or speed change.



In all of this experimentation, only one time did the settings produce CHTs & EGTs (by-the-way, EGTs were in the 1500 range at max lean) that were steady for over 15 minutes.  Reproducing the setting was fruitless.  



Only one time did the #4 CHT go above 450.  This was during a full power lean-of-peak setting.  Gradually pulling the power back (no change in mixture setting) stopped the increase at 465 and all cylinders began getting cooler.  When #4 got to 400, I went back to full power and the CHT went back up to 455 and then back down to 430.  Very weird.  



When I think of all the cross country flights (or local flights) without an engine analyzer, I wonder how many times the engine was really running over maximum temps.



Gary

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bkspero

Joined: 23 May 2012
Posts: 17

Posted: Thu Sep 17, 2015 2:48 am Post subject: Re: In-flight CHTs

Hi Gary. Give Clytie my best regards. 



Try downloading and plotting the data. Sometimes I can see things in a broad overview that aren't apparent otherwise. I find that the free plotting features of the Savvy Analysis website are the easiest way to look at engine analyzer data. 



Barry Speronello

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bvnj(at)yahoo.com
Guest

Posted: Thu Sep 17, 2015 4:10 am Post subject: In-flight CHTs

Hi Gary,



I think this engine is not fully broken in yet. The temps should stabilize once it is fully broken in. My temps also were all over the place until after 50 hours or so. 



Boris

 	  Quote: 	
		  >>>>>>>

 Last Sunday my wife, Clytie, and I flew N626FT back to Auburn from Salt Lake City.

 It has a fairly new engine;  less than 20 hours on it.  The engine is a tricked

 out engine from LyCon.  It also has a Power Flow Exhaust System.  

 

 Getting to SLC was at full throttle and richened to keep the CHTs under 430 on

 an EDM 800.  We got terrible gas mileage.

 

 Coming back, we went up to 12,500 feet (set the heading and altitude with an S-Tec

 30) and I played with the mixture, throttle, and carb heat settings to see

 what I could get.  The interesting observation was that I could quite easily

 get the engine to run smooth lean-of-peak.  The odd thing was, at full throttle,

 it wouldnt stay there. I can only think it had something to do with local temps

 and pressures.  

 

 What I observed was: #1 & #2 were always the coldest (by about 10 to 20 degrees)

 and I never thought much of them.  Between #3 & #4, #3 was the first to go lean

 of peak and was very predictable. #4, however, would go lean, run smooth for

 a while, then it would richen enough to raise the CHTs.  I left the setting

 alone and just observed the outcome.  The CHT would go from 405 to 415 and back

 (plus or minus 10 degrees).  Then, occasionally, keep getting hot to 450 and

 then go lean again and the temp would go down; one time to as low as 397.  

 

 If I leaned slightly more to keep #4 cooler, it would run OK for a while, go lean

 enough to run rough for a while.  I tried carb heat to see if it had any effect.

 Minimal effect at best.

 

 Then I tried pulling the power back to 50% (well, between 50% and 55%) and various

 lean settings.  The lean-of-peak setting was a lot more sensitive.  I aimed

 for a maximum CHT of 415.  As before, the engine would run great for a while

 and then the CHTs would move up or down for no apparent reason; i.e., no RPM

 change, no throttle, mixture, altitude or speed change.

 

 In all of this experimentation, only one time did the settings produce CHTs & EGTs

 (by-the-way, EGTs were in the 1500 range at max lean) that were steady for

 over 15 minutes.  Reproducing the setting was fruitless.  

 

 Only one time did the #4 CHT go above 450.  This was during a full power lean-of-peak

 setting.  Gradually pulling the power back (no change in mixture setting)

 stopped the increase at 465 and all cylinders began getting cooler.  When #4

 got to 400, I went back to full power and the CHT went back up to 455 and then

 back down to 430.  Very weird.  

 

 When I think of all the cross country flights (or local flights) without an engine

 analyzer, I wonder how many times the engine was really running over maximum

 temps.

 

 Gary

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teamgrumman(at)yahoo.com
Guest

Posted: Fri Sep 18, 2015 12:59 pm Post subject: In-flight CHTs

Thanks Barry,



I kept a pretty close watch on the temps.  I could easily run it cooler.  I ran it at peak EGT to see if I could run the engine LOP for extended periods of time.  The high EGT and lean mixture makes for hight CHT.



Gary

 	  Quote: 	
		   On Sep 17, 2015, at 3:48 AM, bkspero <bkspero(at)gmail.com> wrote:

 

 

 

 Hi Gary. Give Clytie my best regards. 

 

 Try downloading and plotting the data. Sometimes I can see things in a broad overview that aren't apparent otherwise. I find that the free plotting features of the Savvy Analysis website are the easiest way to look at engine analyzer data. 

 

 Barry Speronello

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=447143#447143

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