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preheat with a heat gun?


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I suggest caution, a Heat Gun is not a hairdryer. The concentration of heat put out by a gun is phenomenal and could ignite the engine.

A small, high quality ceramic space heater would serve you better, you want gentle, controlled heat.

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58 minutes ago, HRM said:

I suggest caution, a Heat Gun is not a hairdryer. The concentration of heat put out by a gun is phenomenal and could ignite the engine.

A small, high quality ceramic space heater would serve you better, you want gentle, controlled heat.

+1 on caution using a heat gun.  A significant risk is heating electrical insulation to the point that it softens.  Any electrical conductors that are in contact with other conductors, or metal in the airframe could eventually ground out.  If the resulting fault current isn't enough to trip the breaker you could have localized high-resistance heating, leading to a fire.

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I have an EZ-heat pad, very easy to install and comes with paperwork, about $150.  For real cold also a red dragon propane heater that was fortunate came with the plane.  Again if very cold, I run a space heater in the cabin while i'm getting things ready and preflight.  Always have a fire extinguisher at the ready.  Thing can go wrong and have seen it happen to a friend's plane.  The fabric covered plane next to him didn'tdo well either

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On 11/5/2020 at 1:13 PM, Hank said:

Tanis also works well, a heater pad on the oil pan.

REIF is cheaper and better in my experience.  Either will do the trick.  A set of rings and pads is fast and more importantly heats everything evenly.  
 

If you are going to fly in the winter seems to me @$1000 is pretty cheap protection on a $30K+ engine versus using Rube Goldberg contraption.  

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That picks up a few different challenges...

1) Low output of heat...

2) Your car engine is good at putting out heat, do you want to run it for an hour to do this?

3) inverting DC power to AC, to run a heater... is a high tech work around for a system that doesn’t care...

4) Get 12V space heater, plug it in...

5) get HF generator, and use it instead of the car...

6) Don’t think about using the car’s exhaust as a source of heat... too much other chemistry being blown with it...

7) To get the engine started...

  • heat the intake tubes sufficiently... that will evaporate the fuel... (especially for an M20C)
  • heat the cylinders sufficiently... keeping the fuel evaporated in the chamber works wonders...

8) Warm the oil... this is for the health of the engine during the first few minutes of running...

9) Don’t heat the fuel... this would give you the hot start challenges at a time that is really unwanted to have additional challenges...

PP thoughts only, not an electrical engineer...

Best regards,

-a-

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15 hours ago, carusoam said:

That picks up a few different challenges...

1) Low output of heat...

2) Your car engine is good at putting out heat, do you want to run it for an hour to do this?

3) inverting DC power to AC, to run a heater... is a high tech work around for a system that doesn’t care...

4) Get 12V space heater, plug it in...

5) get HF generator, and use it instead of the car...

6) Don’t think about using the car’s exhaust as a source of heat... too much other chemistry being blown with it...

7) To get the engine started...

  • heat the intake tubes sufficiently... that will evaporate the fuel... (especially for an M20C)
  • heat the cylinders sufficiently... keeping the fuel evaporated in the chamber works wonders...

8) Warm the oil... this is for the health of the engine during the first few minutes of running...

9) Don’t heat the fuel... this would give you the hot start challenges at a time that is really unwanted to have additional challenges...

PP thoughts only, not an electrical engineer...

Best regards,

-a-

Agree, but in addition to the oil, heating the cylinders & pistons is good if it’s really cold and the clearances are reduced by the contraction.  If you heat the oil long enough and cover the cowl with a blanket, I bet it warms the top of the engine too.  

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  • 2 weeks later...
On 11/8/2020 at 10:16 PM, carusoam said:

2) Your car engine is good at putting out heat...

Just going to throw this out and keep in mind I'm an EE who is thermodynamically challenged, but has anyone thought of running a hose from their car exhaust up into the engine compartment of their Mooney? Of course, we are talking outside of the hangar or with the door open. Sit in your car and stay toasty while it warms up the engine.

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25 minutes ago, HRM said:

Just going to throw this out and keep in mind I'm an EE who is thermodynamically challenged, but has anyone thought of running a hose from their car exhaust up into the engine compartment of their Mooney? Of course, we are talking outside of the hangar or with the door open. Sit in your car and stay toasty while it warms up the engine.

I read previously that folks are concerned with moisture and corrosive combustion products. At this point, I'm sold on the Reiff preheat system.

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33 minutes ago, HRM said:

Just going to throw this out and keep in mind I'm an EE who is thermodynamically challenged, but has anyone thought of running a hose from their car exhaust up into the engine compartment of their Mooney? Of course, we are talking outside of the hangar or with the door open. Sit in your car and stay toasty while it warms up the engine.

Lots of water in engine exhaust. The primary exhaust gases are CO2 and H20, plus other fun things like CO, NOx, etc. Not the best thing to pump into your cowling or exhaust pipes.

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34 minutes ago, Hank said:

Lots of water in engine exhaust. The primary exhaust gases are CO2 and H20, plus other fun things like CO, NOx, etc. Not the best thing to pump into your cowling or exhaust pipes.

I’ve always heard that for every 8 gallons of gasoline burned 1 gallon of water is produced

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1 hour ago, RLCarter said:

I’ve always heard that for every 8 gallons of gasoline burned 1 gallon of water is produced

I had to think about that one, that initially made no sense to me.  8 gallons of gas should turn into 9 gallons of water (and about 150 lbs of CO2).

I suspect if people say that, they are subtracting the initial volume of gas from the amount of water produced (which makes no logical sense but does make sense intuitively)?

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29 minutes ago, jaylw314 said:

I had to think about that one, that initially made no sense to me.  8 gallons of gas should turn into 9 gallons of water (and about 150 lbs of CO2).

I suspect if people say that, they are subtracting the initial volume of gas from the amount of water produced (which makes no logical sense but does make sense intuitively)?

I’m asking because I’m no chemist... if 8 gallons of gas (~48lbs) get burned, how does it turn into ~213lbs of byproduct (150lbs CO2 & 9 gallons water)?  Is it combining with that much O2 while burning?  My simple mind says the weight in vs weight out should be similar...

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53 minutes ago, Ragsf15e said:

I’m asking because I’m no chemist... if 8 gallons of gas (~48lbs) get burned, how does it turn into ~213lbs of byproduct (150lbs CO2 & 9 gallons water)?  Is it combining with that much O2 while burning?  My simple mind says the weight in vs weight out should be similar...

1 gallon of gasoline produces 18-20 lbs of CO2.

https://climatekids.nasa.gov/review/carbon/gasoline.html

https://blueskymodel.org/gallon-gas

A gallon of gasoline produces slightly more than 1 gallon of water:

http://www.applet-magic.com/watervapor01.htm

 

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I’m asking because I’m no chemist... if 8 gallons of gas (~48lbs) get burned, how does it turn into ~213lbs of byproduct (150lbs CO2 & 9 gallons water)?  Is it combining with that much O2 while burning?  My simple mind says the weight in vs weight out should be similar...

 

in simplest terms, each molecule of gasoline(octane C8H18) uses  17 molecules of Oxygen and produces 8 molecules of CO2 and 18 molecules of Water. 

 

so the 8 gals of gas has approximately 40.5 lbs of pure C atoms and 7.5 lbs of H.   The 40.5 lbs of C consumes  216 lbs of oxygen  the end result is what you get.

 

 

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Just now, clh said:

I’m asking because I’m no chemist... if 8 gallons of gas (~48lbs) get burned, how does it turn into ~213lbs of byproduct (150lbs CO2 & 9 gallons water)?  Is it combining with that much O2 while burning?  My simple mind says the weight in vs weight out should be similar...

 

in simplest terms, each molecule of gasoline(octane C8H18) uses  17 molecules of Oxygen and produces 8 molecules of CO2 and 18 molecules of Water. 

 

so the 8 gals of gas has approximately 40.5 lbs of pure C atoms and 7.5 lbs of H.   The 40.5 lbs of C consumes  216 lbs of oxygen  the end result is what you get.

 

 

Ahh, thanks.  That’s a lot of oxygen consumed!

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1 hour ago, Ragsf15e said:

Ahh, thanks.  That’s a lot of oxygen consumed!

Consider the stoichiometric air/fuel ratio is pretty high for vaporized fuel, and the displacement of an aircraft engine is quite high and moves a LOT of air volume through in every two revolutions, but does not use much fuel in just two revolutions.   It takes a lot of O2 to burn a little fuel, so it's a significant contributor to the output.   It's also an interesting example of how high the energy density is in gasoline.   There aren't many things that come close that are easily portable.


 

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Oh man, this is making me travel back in time to chemistry class. I hated balancing equations, but his one is pretty simple. Avgas is a complex brew of hydrocarbons and other chemicals, but to use the octane example, complete combustion would combine the octane with just enough oxygen to result in the production of only carbon dioxide and water.

2C8H18 + aO2 =bCO2 + cH2O

Balancing carbon: b=16

Balancing hydrogen: c=18

Balancing oxygen: 2a = 2b + c, or a =25

I'll let someone else figure out the weights :)

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