REFLECTOR: Cold Weather Flying

Sat Dec 22 12:43:42 CST 2012

Rene',

There is no way to tell what temperatures inside your engine the oil is 
exposed to. Let's suppose that the bottom of the pistons are 400F when the 
oil temperature reads 200F.  If the indication went to 400F then the oil 
inside the engine will be subject to temperatures that are way above any 
reasonable values.  Don't forget that increased temperatures also cause a 
loss of viscosity.  Not only that but hotter pistons can cause detonation. 
Bottom line,  excessive temperatures will destroy your engine, never mind 
what it does to the oil.

Larry Coen
N136LC

--------------------------------------------------
From: "David Rene Dugas" <renedugas at gmail.com>
Sent: Friday, December 21, 2012 10:33 PM
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Subject: Re: REFLECTOR: Cold Weather Flying

> Larry,
> I did not know that. Sooooo 300-400 is ok?  Not desirable but ok?
>
> Rene' Dugas
> Sent from an Apple.
>
> On Dec 21, 2012, at 5:00 PM, "Laurence Coen" <lwcoen at hotmail.com> wrote:
>
>> Most engine applications measure the oil temperature where it enters the 
>> engine oil galleys   In other words, after it has gone through the oil 
>> cooler.  Oil that is splashed against the bottom of a piston gets much 
>> hotter.  Not to worry, petroleum based oil starts to "coke" at 
>> temperatures above 608F.  The only place that this is likely to happen is 
>> in a turbocharger.
>>
>> Larry Coen
>> N136LC
>>
>> --------------------------------------------------
>> From: "John Dibble" <aminetech at bluefrog.com>
>> Sent: Friday, December 21, 2012 4:44 PM
>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>> Subject: Re: REFLECTOR: Cold Weather Flying
>>
>>> Oops.  I meant 175F.  Thanks for pointing that out, Rene, Scott.
>>>
>>> John
>>>
>>> On 12/21/2012 4:05 PM, Scott Derrick wrote:
>>>> I noticed that too but forgot to say something.  275f is above any red 
>>>> line I've ever seen.  That oil is cooked.
>>>>
>>>> David Rene Dugas <renedugas at gmail.com> wrote:
>>>>
>>>>> No one else commented so I will. The oil temp seems quite high. Maybe 
>>>>> dangerously.
>>>>>
>>>>> Rene' Dugas
>>>>> Sent from an Apple.
>>>>>
>>>>> On Dec 21, 2012, at 10:04 AM, John Dibble <aminetech at bluefrog.com> 
>>>>> wrote:
>>>>>
>>>>>> Had a good flight from MS to NY on Wednesday.  Stopped at DKX 
>>>>>> Knoxville for fuel.  That's a hard airport to find hidden in the 
>>>>>> hills.  A while back I reported that my temps were too low in cold 
>>>>>> weather and not enought cabin heat.  I decided to go after the source 
>>>>>> of the heat and reduce the engine cooling air, see pic.  I thought 
>>>>>> this would be over kill and I would have to trim it a bit, but it 
>>>>>> turns out that this just gets the engine temps to the bottom of the 
>>>>>> desired range (250-300F) with an OAT of 40 F.  At 30F CHTs are 
>>>>>> 240-245F.  Still, the oil temp ran at 275F with the diverter flap 
>>>>>> fully deployed and that gave too much cabin heat.  During descent for 
>>>>>> landing, temps got very low and I had no cabin heat.  I would like to 
>>>>>> have a way to adjust engine cooling air from the cabin, so I can have 
>>>>>> max cooling for T/O and reduce cooing air at cruise and reduce it 
>>>>>> further for descent.  Has anyone done this?
>>>>>> When the OAT got down to 30F, I decided it would be a good idea to 
>>>>>> add some carb heat even though my manifold pressure was holding 
>>>>>> steady.  I did not see an expected increase in the carb temp gauge, 
>>>>>> but the MP did decrease by a few tenths indicating that the carb heat 
>>>>>> was working. Guess I need to work more on the the carb temp sensor 
>>>>>> placement.  I had moved it to the fitting where the manifold pressure 
>>>>>> line connects (carb outlet).  It seemed to be giving sensible 
>>>>>> readings at higher OATs, but not at 30 F where it counts. Looking 
>>>>>> forward to returning to warmer weather after the holidays.
>>>>>>
>>>>>> John
>>>>>>
>>>>>>
>>>>>> <cooling air scoop.jpg>
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