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  #1  
Old 06-11-2017, 10:29 AM
texdog texdog is offline
 
Join Date: Jan 2013
Location: Fredericksburg, Tx.
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Question High cylinder head temp at altitude

Yesterday at 14,500 ft. 0-360, 17 inches of manifold and 2550 RPM, my number one cylinder required 1/2 gph more fuel flow to keep it at 380 degrees or less and EGT was 150 degrees hotter. I was at altitude for over two hours. In addition my volts were running 13.8 to 14.1. The voltage alarm is set for 13.8, for low. Are these normal occurrences, do I need to check exhaust and intake gaskets and maybe alternator belt. The belt is 7 years old 750:00 hours, but looked good in March at the condition inspection.
Thanks
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  #2  
Old 06-11-2017, 11:07 AM
brad walton brad walton is offline
 
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Ive noticed higher CHT at altitude even as fuel flow for same speed decreases. I assumed this is a result of less airflow over cylinder heads due to less air density.
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  #3  
Old 06-11-2017, 12:10 PM
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bret bret is offline
 
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Air intake tube leak on #1? running lean from a leak?
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  #4  
Old 06-11-2017, 12:25 PM
vic syracuse vic syracuse is offline
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Depending on the time of year and temps, it is normal to see a little higher CHT's at altitude. The air less dense. As mentioned, do check the intake tubes for leaks, typically found by looking for blue fuel stains around the upper attach point to the cylinder.

Your volts warning is set too low. 12.8-13.0 is a good low voltage setting. Any reading above that is usually indicative of a working alternator.

Vic
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  #5  
Old 06-12-2017, 05:36 AM
texdog texdog is offline
 
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Location: Fredericksburg, Tx.
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Smile High cylinder temp and voltage

Thanks for the help. I will pull the cowling and check. I'm going to change the intake clamps and tubes anyway. Vic. Thanks, I will lower the alarm.
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  #6  
Old 06-12-2017, 07:13 AM
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Toobuilder Toobuilder is offline
 
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Considering your altitude and MP, I'm guessing you were WOT... Intake leak will not show up as an issue. The throttle blade is the biggest leak in the system. Are you FI or carb?

Also, the air is pretty rare up there.... What is your overall baffle health? Have you looked into the need for the bypass duct on #1 and #3 to get past the zero fin depth issues?
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Last edited by Toobuilder : 06-12-2017 at 09:29 AM.
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  #7  
Old 06-12-2017, 12:24 PM
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F1Boss F1Boss is offline
 
Join Date: Aug 2006
Location: Taylor Texas
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Default DOH!!

Quote:
Originally Posted by Toobuilder View Post
Considering your altitude and MP, I'm guessing you were WOT... Intake leak will not show up as an issue. The throttle blade is the biggest leak in the system. Are you FI or carb?

Also, the air is pretty rare up there.... What is your overall baffle health? Have you looked into the need for the bypass duct on #1 and #3 to get past the zero fin depth issues?
Mike is right - an intake leak is almost a non issue at full throttle. That defect shows up at idle.

I find my engine needs a bit more fuel than I thought it might at higher altitudes - lower altitudes allow for 11gph at similar power settings, so the rarified air could be your cause. I have heard this is an issue with some turbo'd engines, so don't feel too bad!

Check baffling for any leaks. And I do mean ANY. The DanH approach (Ultra Black over 9oz cloth) to baffling is the best I have seen. Atta boy Dan!

https://photos.smugmug.com/photos/i-...-nZLFSgQ-S.jpg

https://photos.smugmug.com/photos/i-...-BQFnPVV-S.jpg

Carry on!
Mark

Last edited by F1Boss : 06-12-2017 at 12:34 PM. Reason: add pictures
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