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  #1  
Old 06-24-2021, 08:44 PM
laruetou2 laruetou2 is offline
 
Join Date: May 2019
Location: Reno
Posts: 9
Default A touch of carb heat all the time

All,
Because of time constraints on cowl improvements, I have a situation whereby my carb/airbox is sucking air from the bottom half of the cowl, with no fresh air inlet. Down the road that will be remedied. For now it's like I have a little bit of carb heat all the time. Not the best for achieving best power, but is it doing any harm?

CHTs and oil temps seem to be within parameters and I'm guessing that atomitaziton of the fuel is probably slightly better with the warmer air temps. I'm looking at doing a 400 mile x-country in this condition and wondering, again, so long as temps are in line, is this air intake situation doing any harm?

I thank you in advance for thoughts and ideas.
Larry
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  #2  
Old 06-25-2021, 04:55 AM
pa38112 pa38112 is offline
 
Join Date: Mar 2008
Location: Clarksboro, NJ
Posts: 1,031
Default

Your engine is ingesting unfiltered air. That is not the best situation.
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  #3  
Old 06-25-2021, 05:02 AM
Desert Rat Desert Rat is offline
 
Join Date: Aug 2018
Location: Wichita KS
Posts: 857
Default

I took it to mean that its filtered, but just not sucking from outside.

You already know about the power loss and potential for it to run rich, but as long as you deal with that, I don't see that it's a big deal, other than maybe under certain conditions the potential for carb ice might be a little greater.

I'd be interested to hear dissenting opinions...
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  #4  
Old 06-25-2021, 06:46 AM
A2022 A2022 is offline
 
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Default

just be aware.....if a working carb heat system is required for your aircraft, then a takeoff with a non working system could be seen by the FAA as a violation.
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  #5  
Old 06-25-2021, 06:53 AM
pa38112 pa38112 is offline
 
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Location: Clarksboro, NJ
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Aaaa, I thought he was saying it is bypassing the filter box. If there is no ram air inlet below the cylinders then yes you are loosing performance (maybe), but no, there is no harm being done. This actually could be helping you. Is it a carbureted engine? The warmer air will help atomize the air and may be giving you better engine performance. You are also likely getting better air flow through your oil cooler, and your plane will be a bit faster.
Is there any reason to believe you are not making full power? How are your engine and oil temps? How far lean-of-peak can you cruse?
I would not change it unless you have data saying that you are not getting performance. It was built that way for a reason, and changing it could induce a number of un-intended results. It all depends on how much thought the builder put into this approach.
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  #6  
Old 06-25-2021, 08:51 AM
laruetou2 laruetou2 is offline
 
Join Date: May 2019
Location: Reno
Posts: 9
Default There is an air box with a filter and conventional carb heat

Thanks to all for the thoughts and comments.

Title updates the original post and, yes, it's carbed. So far it sounds like if I'm comfortable with the potential reduction of power that it's a green light to operate this way. For monitoring 2 CHTs and 2 EGTs I'm using a Vega TC-4 and, in conjunction with a vernier mix control, I can lean it out pretty precisely. I'm still learning the aircraft and can not today answer the question on leaning LOP.

pa38112 - no oil cooler (Ly O-235-K). Loss of power would not be much (5 to 10%) - I can make 2650 on an ultra cruise prop (for this ship). The aircraft story is a bit of a long one and probably not worth telling right here but there was a longer airbox contraption (made by previous builder) that did extend to the front of cowl and allowed ingestion of fresh (and filtered) air. I deemed it not airworthy and replaced it (temporarily) with one I had on the shelf.
Larry

Last edited by laruetou2 : 06-25-2021 at 09:06 AM.
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  #7  
Old 06-25-2021, 04:09 PM
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Jpm757 Jpm757 is offline
 
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Location: Sherman, CT
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Be careful what you post on the forums. If you decide to fly the aircraft and have an incident, the FAA may very well consider you to have operated the aircraft with a known deficiency.
Big Brother IS watching!
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  #8  
Old 06-25-2021, 09:19 PM
laruetou2 laruetou2 is offline
 
Join Date: May 2019
Location: Reno
Posts: 9
Default No known deficiencies

I do not conduct my life by what the risks are of some nutball governmental agency slicing and dicing my communications and finding them suggestive and, therefore, me at fault. I'm way too old for that ****.

Again, I thank those that contributed to the technical discussion.
Cheers,
Larry
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