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Engine pre-heat guidelines

mbuto

Member
Greetings!

My 9A is my first airplane. Today, I pulled it out of its unheated hangar for my first cold weather start. It was a struggle, but eventually I got it started. I have an Earthx battery, and it performed well.

So, I think I should install an engine pre-heater, and it looks like the E-Z Heat from Aircraft Spruce is a reasonable choice. Not sure if the 440 with the 4"x4"x1/32" pad is what I should get or the 441 with the 3-7/8"x5"x1/32" pad.

Any thoughts? Other cold weather tips? Should it be on all the time, or can I use it on a timer to reduce energy costs? I'm located in the Vancouver BC area.

TiA

Mike
 
Engine oil heater

I have an EZ oil heater since 2005 on my IO-360 and it works well.
It heats the oil and the oilpan but it can´t heat the entire engine.
This means that the upper parts will be cold while the oilpan is warm.
If you leave it on 24/7 you may get water condensation in the upper parts
inside the engine. Not what you want.
I use the EZ heater below +5 C for 1 h.
If it gets below -0 C, for 2 h.
My experience is that cold wether, you need to prime more.
A cellphone operated relay can be a good idea.

Good luck
 
I just have a dual 200W pad Rief heater that gets the oil up above “cold” to “warm” after an hour or two. I use cell phone switch to turn it on from home.
I stick a 100w incandescent light bulb up in through the bottom of the cowl and keep that on 24/7 with an old thick comforter draped over top of cowl with cowl plugs. That seems to keeps the engine from getting too cold soaked between flight.
You situation may very significantly based on outdoor winter temps and if in a hangar or not. I live in STL were low temps in winter average about 15-20F with occasional temps down to 0F. I don’t fly if temps are below 0F.
 
I just finished my 9A. I also needed a sump heater. I have the superior cold air induction and the only heater that fit perfectly was the Reiff hot strips. It may depend on what oil sump you have as to what fits the best.
 
I have a Reiff XP with bands and sump on a Switcheon cell phone switch (brilliant device - I highly recommend as simplest, most reliable, and cheapest such switch I could find).

The preheater will take my oil from 20° ambient to over 100° in about 3-4 hours. I don't leave it on all the time, I usually call to turn it on the night before a flight. I do have an engine dehydrator that I built because heating/cooling will always take the engine across the dew point.

I also have a Hornet 45 cockpit heater on the same Switcheon device. That takes my ConforFoam seats from stiff-as-a-board to comfy and toasty in short order.

This is Minnesota. Preheating is serious business .
 
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Remove your oil cap, plug in 24 hrs, cover the engine with a sleeping bag. - entirely warm engine, no moisture. Immediately remove oil cap each flight all year to vent the xs moisture. 50w Kats pad heater- overall engine compartment temps of 80 - 100 pending oat. my .02 after many years of success.
 
+1 on Kat's

In the hangar with an old blanket over the cowl an auto oil sump heater works fine. You can prove this empirically-- just look at your engine monitor prior to start. For me, all CHTs and oil are within a couple degrees of 70F at 20F OAT. May be different in a more loosely cowled a/c.
 
I use the Reiff hot-pads on the sump with a cellphone-controlled switch, the Switcheon. As others have noted it works well over 3-4 hours, and even with 2 hours it will get my sump/oil into the 80-90F range.

As a rule I want to see 80 degrees before taxi, and 100 before takeoff.
 
As a rule I want to see 80 degrees before taxi, and 100 before takeoff.

What rpm do you idle at during warm up before taxi?
I always wonder the trade of a bit higher rpm to warm faster and therefore less time at idle or low rpm idling which will take a bit more time to get warm. Or does it matter?
 
We should probably note that different parts of the world, different parts of the US, have widely varying seasonal temps, therefore may have widely varying pre-heat needs. One set of recommendations does not apply to all. Vancouver, however, has pretty mild winter temps making pre-heating likely to be somewhat less of a challenge.
 
WiFi

The cell switches work fine and easy to make. Let's not forget if your hangar has Wi-Fi (As both of mine do now) you can use a cheap Wi-Fi switch and no monthly fees. My Reiff sump heater worked great in the Ohio weather.
 
What rpm do you idle at during warm up before taxi?
I always wonder the trade of a bit higher rpm to warm faster and therefore less time at idle or low rpm idling which will take a bit more time to get warm. Or does it matter?

Lots of opinions and little fact in this area. I have yet to find an official recommendation, post radial engines anyways, that either recommends or even suggests that OT needs to be 100* before application of full power, especially with multi-viscosity oils (i would think differently if running 100 wt oil in 30* ambient temps, but then again Lycoming is clear that this is not recommended). I don't think I have ever taken off after a cold start with OT above 100* Engine in fine shape at 875 hours. I do worry about scuffing due to the different expansion of alum pistons and steel cylinders and will not take off until CHTs are 250. That is just my guideline, not taken from any source. Just imagine how much extra gas we would consume if every car was not driven until OT was 100* That is 15-20 minutes here in Midwest winters. Yep, this is where everyone tells me airplane engines are different. No different than my 911 air cooled boxer engine, also with no recommendation to get OT up to 100* before driving it, though some very knowledgeable people recommend keeping revs under 4K until over 125 OT.

I see guys here in the winter sitting on the ramp idling for 15 minutes to reach that magic number and just don't get it.

Larry
 
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Crisp/calm 0-30F days can be the best!!

What rpm do you idle at during warm up before taxi?
I always wonder the trade of a bit higher rpm to warm faster and therefore less time at idle or low rpm idling which will take a bit more time to get warm. Or does it matter?

If needed I use 1200 rpm. It does not take long and gives a chance for cockpit organization and pre-takeoff adjustments.

Diesel white smoke and warm up tests were done in the '80s and the warmup time was zero at low idle and the ideal measured in 1100-1300 rpm. Lots of testing and different issues, but seems to work for the plane driving a prop.

+1 for all the Reiff pads and cylinder bands. A composite prop does not chill the engine but some will need a hub/blade insulator. It is more of a factor that one imagines.

I like the 100F before takeoff just to keep the oil high pressure alarm from going off. My system as an accumulator so that is a consideration.

I use an engine crankcase purge and dry on each flight so only initiate preheat based on ambient temps. The Switch e ON has an ambient temp indicator and works well with phone activation.
 
Snip - I have an Earthx battery, and it performed well.

Mike - warming up your EarthX is also a good idea. I normally turn on all the lights during preflight and then raise/lower/raise the flaps before hitting the start switch.
 
Reiff

I have a Reiff system on my -10. Pad on the sump and band heaters on the cylinders. I also use the Switcheon box and turn it on the night before or a couple hours before I go, depending on OAT. I get between 75 and 85 degrees by the time I am ready to start.

Starts right up with EFII, I use about 950 rpm or so for the first couple of minutes; lower than 850 and the second alternator is off line.

Takeoff with 0ver 100, usually shoot for 120 or above.
 
I'm going to put in a plug for Switcheon as a cell-phone switch. I have no connection to the company but have been very impressed with their attention to customer service and commitment to making sure things work well.

All you need is a cell signal, and not even a very good one. It doesn't use sims, or cell phone accounts, text messaging, hot spots, or any of that other s stuff. It's a simple app, and uses IoT (internet of things) so bandwidth requirement is extremely low. Could not be simpler to use, and has been completely reliable.

..
 

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Lycoming operating manual....


a. Head the aircraft into the wind.

b. Leave mixture in “Full Rich”.

c. Operate only with the propeller in minimum blade angle setting.

d. Warm-up at approximately 1000-1200 RPM. Avoid prolonged idling and do not exceed 2200 RPM on the ground.

e. Engine is warm enough for take-off when the throttle can be opened without the engine faltering.
 
"Generally, I consider any start in which the engine is cold-soaked to a temperature below freezing (32 degrees Fahrenheit, or 0 degrees Celsius) to be a misdemeanor and any start below about 20 degrees F (minus 7 degrees C) to be a felony." - https://www.aopa.org/news-and-media...lot/savvy-maintenance-crimes-and-misdemeanors

https://www.lycoming.com/content/op...most Lycoming models, preheat,are below 20˚ F.


That being said, one of those old milk-house heaters with some dryer duct blowing warm air (not hot) into the lower cowl for 10 or 15 minutes will make it easier to start on those 33f-45f mornings. Also, in cooler weather a carbureted engine will demand much more fuel to prime for the first start of the day.
 
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Any thought on the Twin Hornet 22 - Engine Preheater + blanket option? A remote cel option looks good too, but I am in Canada, so that may require some extra thought.
 
In an area where winter temps are typically 30s - 40s (F°), the Twin Hornet 22 might work fine. I can't attest...I have more robust needs, and my cowl and intakes are not particularly amenable to that configuration. I can endorse the quality of construction by that company as I do use a Hornet 45 cockpit heater and like it a lot.
 
In an area where winter temps are typically 30s - 40s (F°), the Twin Hornet 22 might work fine. I can't attest...I have more robust needs, and my cowl and intakes are not particularly amenable to that configuration. I can endorse the quality of construction by that company as I do use a Hornet 45 cockpit heater and like it a lot.

What is different about your cowl that would make this heater a poor choice for your plane? All RV's are the same?

Mid 20's to mid 40's (F) would be of concern here.
 
What is different about your cowl that would make this heater a poor choice for your plane? All RV's are the same?

Mid 20's to mid 40's (F) would be of concern here.

All RV's are similar. I have a carbon fiber-capped plenum which leaves no room to shove a pair of Hornet 22's in there. I have zero interest in de-cowling to apply pre-heat and find that a Reiff XP sump heater and cylinder bands perform that pre-heat function much more efficiently in my particular local climate. All I have to do is remember to plug it in to the cell-phone siwtch before I leave the hangar...just another step in addition to plugging in the dehydrator and the battery maintainer. My Turbo XP is entirely plug-and-play, and all I have to do is pull up the app and turn it on remotely about 4-5 hours in advance from wherever in the world I happen to be.
 
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Twin Hornet 22 - does it fit in the cowling?

Does anyone know if the Twin Hornet 22 preheater fits in the cowling of a 9-A with an o-320?
 
Does anyone know if the Twin Hornet 22 preheater fits in the cowling of a 9-A with an o-320?

They look like very good devices, but hard to know if they will fit under your cowl. I doubt they would fit under mine.

I bought a pair of these "mini desktop heaters", available from all your favorite Chinese product suppliers like Aliexpress and Amazon:

https://www.amazon.com/Safety-Energy-saving-Portable-Desktop-Electric/dp/B09GYJZJCJ/

I stuff them between the exhaust pipes, have them connected to a remote power plug, and I turn it on a few hours before flying, and my entire engine compartment is warm even on the coldest below freezing days. I have cowl plugs and a moving blanket over the cowl to try to hold the heat in, and to keep the bird droppings off the paint.

Not as sexy as the hornets, but smaller and cheaper.
 
Red Dragon Heater

001.jpg


I use one of these. Can't be activated remotely, but it sure heats things up quickly. Unfortunately I don't believe they available any longer.
 
Having just spent an embarrassing length of time installing a Tanis heater and routing the wires, I don’t think I’d do that again. I might just put a sticky on the sump or, better yet, get an Alien heater and be done with it.
 
Given enough time ( overnight) the EZ-Heat pads DO warm up the entire engine. After an overnight pre-heat my oil temp, CHT's and EGT's are all identical, usually around 85-90F with OAT's in the single digits. If you don't have the time or patience then the Reiff does the job faster.
 
what the aviation world needs is a scientific study about relative humidity vs. temp. on the rate of corrosion. warm air in your engine has the same amount of h2o in it as cold air but rel. humidity is lower. however, every 10 deg c. rise [i know a lot out there already know this] doubles the rate of chemical reaction.
so what's best? i think for the corrosion business the less preheat the better. .
i warm the upper engine and the oil sump a couple hrs before a flight. i think there is some truth to warming oil only causes condensation on cold upper engine surfaces. but who knows for sure. i do know that nothing rusts in my pole barn when it's zero out.
 
+1 for switcheon. Side benefit is it will give you the temp in the hangar at anytime. I live in a cold climate (WI) and have a sump pad heater plus a heating element/probe that goes inside the suction screen. Cover the cowl with a fitted Harbor Freight moving blanket and leave it on for up to 8 hrs if really cold (down to 0 degrees F). I do like the idea of opening the dipstick after flight to exhaust moisture. Currently don't do that but may start.
Keith

I'm going to put in a plug for Switcheon as a cell-phone switch. I have no connection to the company but have been very impressed with their attention to customer service and commitment to making sure things work well.

All you need is a cell signal, and not even a very good one. It doesn't use sims, or cell phone accounts, text messaging, hot spots, or any of that other s stuff. It's a simple app, and uses IoT (internet of things) so bandwidth requirement is extremely low. Could not be simpler to use, and has been completely reliable.

..
 
i did watch part of the tanis video. maybe i didn't watch it all so i might have missed it but he seems to be implying that only when water is in liquid form [condensation] can rust form.
rust happens because water carries oxygen that can be given up easily for the formation of rust. ever notice that if you pull a piece of steel from water and then it rusts in the air? i don't know the numbers but i think rust occurs faster in high humidity, warm air. so anyway, the tanis had a lot of info but pretty much about temps avoiding dewpoints.
 
I view pre-heating as having nothing to do with corrosion. For me, it's about mitigating the engine wear of a cold start.

Mike Busch...https://www.aopa.org/news-and-media...lot/savvy-maintenance-crimes-and-misdemeanors:
A single cold start without proper preheating can produce more wear on your engine in less than a minute than 500 hours of normal cruise operation.
The moisture that causes corrosion isn't ambient humidity, it's condensation that occurs when ambient temperature crosses the dew point. As in...the cooling of an engine that has just run, or the normal temp ups and downs of a cool morning in the summer (for example).

The two ways to limit condensation/corrosion are either always keep the ambient crankcase temps above the dew point, or always keep the crankcase humidity below the dew point. I don't want to leave my engine on a pre-heater 24/7/365, so I use a dehydrator 24/7/365.

IMHO.
 
Old man harumphing and calling shenanigans

I view pre-heating as having nothing to do with corrosion. For me, it's about mitigating the engine wear of a cold start.

Mike Busch: "A single cold start without proper preheating can produce more wear on your engine in less than a minute than 500 hours of normal cruise operation."

I have learned a lot from Mike Busch. His books etc. have saved me a ton of money. His campaign against "might as well" so-called "top overhauls" alone should put him in the aviation maintenance hall of fame.

And I don't doubt that preheating helps prevent engine wear. I also preheat just to make starting easier.

But come on! I have read and heard this "500 hours of normal cruise wear" thing from him, and from various other people, for years. I cannot find a shred of evidence supporting the claim. At this point I think it's just an OWT.

I also think it's pretty much self-evidently wrong, at least for any temp above an Alaska deep freeze -- or else any number of hard-ridden flight school aircraft would have the equivalent of 337,000 hours since TBO.

But I am certainly ready to sit corrected! Is anyone aware of any support for this oft-repeated 500-hour claim?
 
001.jpg


I use one of these. Can't be activated remotely, but it sure heats things up quickly. Unfortunately I don't believe they available any longer.

My hangar leasing agreement excludes any open-flame heaters...even mentions Red Dragon by name (contract not updated very diligently). I do occasionally use a propane patio heater in my hangar on a sort of "don't ask/don't tell" basis for cold-weather oil changes or other maintenance but it's of no help for preheating.

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I have learned a lot from Mike Busch. His books etc. have saved me a ton of money. His campaign against "might as well" so-called "top overhauls" alone should put him in the aviation maintenance hall of fame.

And I don't doubt that preheating helps prevent engine wear. I also preheat just to make starting easier.

But come on! I have read and heard this "500 hours of normal cruise wear" thing from him, and from various other people, for years. I cannot find a shred of evidence supporting the claim. At this point I think it's just an OWT.

I also think it's pretty much self-evidently wrong, at least for any temp above an Alaska deep freeze -- or else any number of hard-ridden flight school aircraft would have the equivalent of 337,000 hours since TBO.

But I am certainly ready to sit corrected! Is anyone aware of any support for this oft-repeated 500-hour claim?

I do acknowledge the somewhat dogmatic approach in a lot of what Mike Busch writes. OTOH, I'm confident that his aircraft engine knowledge vastly exceeds mine. That, coupled with the fact that the perils of cold weather starting any internal combustion are well-known and often-reported (google returns 200 million hits) leads me to take his recommendations on the subject at face value. Others who are smarter than I may feel justified in refuting his assertions, but his observations make perfect sense to me so I'm comfortable incorporating his opinions into my own dogma.
 
True

I certainly agree that it's hard to go wrong with following his advice on preheating, my point was only that his justifying data seems... extremely suspect.

Oddly enough, I also follow his advice regarding Lycoming CHTs (e.g. he says it's okay to run Lycoming cylinders at 400 degrees) and people think I'm crazy. :D

I do acknowledge the somewhat dogmatic approach in a lot of what Mike Busch writes. OTOH, I'm confident that his aircraft engine knowledge vastly exceeds mine. That, coupled with the fact that the perils of cold weather starting any internal combustion are well-known and often-reported (google returns 200 million hits) leads me to take his recommendations on the subject at face value. Others who are smarter than I may feel justified in refuting his assertions, but his observations make perfect sense to me so I'm comfortable incorporating his opinions into my own dogma.
 
They look like very good devices, but hard to know if they will fit under your cowl. I doubt they would fit under mine.

I bought a pair of these "mini desktop heaters", available from all your favorite Chinese product suppliers like Aliexpress and Amazon:

https://www.amazon.com/Safety-Energy-saving-Portable-Desktop-Electric/dp/B09GYJZJCJ/

I stuff them between the exhaust pipes, have them connected to a remote power plug, and I turn it on a few hours before flying, and my entire engine compartment is warm even on the coldest below freezing days. I have cowl plugs and a moving blanket over the cowl to try to hold the heat in, and to keep the bird droppings off the paint.

Not as sexy as the hornets, but smaller and cheaper.
Can you provide a picture of this setup? Also, can you give an example of the remote power plug that you use?
 
Can you provide a picture of this setup? Also, can you give an example of the remote power plug that you use?
Sure - I just put these two little heaters in the bottom of the cowl. The fit perfectly between the two exhaust pipes.

They are plugged into a Tapo remotely activated power plug which is connected to my hangar wifi, with a Y splitter to give me two outlets.


A couple more pictures here: http://www.rv8.ch/remote-controlled-engine-heater/
 
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