Preheating engines: Airplane engines versus auto engines

Peter R. wrote:
On 12/19/2007 1:51:18 PM, " wrote:

Might ask your neighborhood FBO to use one of their portable heaters
next time around :-)

I have read in several different mags that those portable heaters only warm
the cylinders and not the bottom end (cam shaft) where the heated oil is most
important during the short time most FBOs run the units. Consequently it is
somewhat a waste of time and energy to use that type of heater.



I use both.

I plug in the pan, while at the same time using a forced air unit.

Peter R. wrote:

Why is it that here in the Northeast US seemingly no one preheats their
automobile engine before start-up in very cold temperatures? Is the long-term
damage the same for both autos and aircraft engines? If so, why do you
suppose auto owners don't typically do this? Is it because that most auto
owners do not keep their cars very long?


Well, I make no claim to KNOW the answer, but I do have a few opinions
about it.

1. Auto engines have tighter tolerances as they are water cooled and
operate over a narrower and better controlled temperature range. They
can thus run thinner oil which starts to circulate much more quickly
than the molasses specified for most aircraft engines.

2. The consequences of engine damage in a car are much lower so it just
isn't worth the hassle of using an engine heater unless it is required
for the car to start.

3. This is a perpetuation of a decades old myth.

I personally believe that the above are weighted roughly as follows:

1. 30%
2. 10%
3. 60%

It would fun to have real data, but that would be very expensive and
time consuming to obtain. I've run many car engines well above 100,000
miles (roughly time equivalent to 2,000 hours, but not total power
produced equivalent to an airplane engine) with cold starts at least 5
months of the year and never had any indication of unusual engine wear.
I've NEVER yet worn out an auto engine in 30+ years of auto ownership.


Matt

Peter R. wrote:
On 12/19/2007 12:39:10 PM, "gpaleo" wrote:

This is joke post, right????

Yes, it's a joke. You can go back to bed now.


No, 6 year-olds should be in school by mid-day, not playing on mommies
computer!

Tauno Voipio wrote:
Peter R. wrote:

--- clip clip --


Why is it that here in the Northeast US seemingly no one preheats their
automobile engine before start-up in very cold temperatures? Is the
long-term
damage the same for both autos and aircraft engines? If so, why do you
suppose auto owners don't typically do this? Is it because that most auto
owners do not keep their cars very long?

Here in the north of Europe We'll pre-heat our cars if
possible, if the temperature goes below +5 C (whatever
it is in F, around 40?).

You can force an engine to start even at -30 C, but it
means that the poor thing runs some time practically
dry of lubrication.


Really? Where does all of the oil disappear to that was there when the
engine was shut down?

Matt

On Dec 19, 4:40 pm, Matt Whiting wrote:
Peter R. wrote:
Why is it that here in the Northeast US seemingly no one preheats their
automobile engine before start-up in very cold temperatures? Is the long-term
damage the same for both autos and aircraft engines? If so, why do you
suppose auto owners don't typically do this? Is it because that most auto
owners do not keep their cars very long?

Well, I make no claim to KNOW the answer, but I do have a few opinions
about it.

1. Auto engines have tighter tolerances as they are water cooled and
operate over a narrower and better controlled temperature range. They
can thus run thinner oil which starts to circulate much more quickly
than the molasses specified for most aircraft engines.

2. The consequences of engine damage in a car are much lower so it just
isn't worth the hassle of using an engine heater unless it is required
for the car to start.

3. This is a perpetuation of a decades old myth.

I personally believe that the above are weighted roughly as follows:

1. 30%
2. 10%
3. 60%

It would fun to have real data, but that would be very expensive and
time consuming to obtain. I've run many car engines well above 100,000
miles (roughly time equivalent to 2,000 hours, but not total power
produced equivalent to an airplane engine) with cold starts at least 5
months of the year and never had any indication of unusual engine wear.
I've NEVER yet worn out an auto engine in 30+ years of auto ownership.

Matt

Matt's answer is right on. My experimental plane has a V-8 347 cu in
all aluminum water cooled engine in it. I keep it in a 50 f hangar, it
has a oil pan heater that cycles at 165 f and it loves it, I run 10-40
racing oil and the oil pressure comes right up on start up. Aircooled
engines spec 100w which is really straight 50 weight, the multi
viscosity aircraft oils are still alot thicker then automotive oils so
they take longer to suck up through the pick up tube and pressurize
the oil galley. As for the original poster I am sure he didn't do any
harm to his motor by starting it at 25 f.

Ben
www.haaspowerair.com

On Dec 19, 11:57 am, "Peter R." wrote:
On 12/19/2007 1:51:18 PM, " wrote:

Might ask your neighborhood FBO to use one of their portable heaters
next time around :-)

I have read in several different mags that those portable heaters only warm
the cylinders and not the bottom end (cam shaft) where the heated oil is most
important during the short time most FBOs run the units. Consequently it is
somewhat a waste of time and energy to use that type of heater.

--
Peter

If you heat the cylinders you'll heat the whole engine.
Metal conducts heat.

25°F isn't cold unless you're running heavy oil, like
W100. We run Aeroshell 15W50 year-round and sometimes start these
things at -10°C which is what? around 14°F? And the engines
(Lycomings) all reach TBO. No metal. We put cowl covers on them after
a flight when they're parked outside and start them later on at temps
to -25°C.

The big danger with cold oil is its reluctance to flow.
The oil pump has to suck the oil up from the sump, and cold oil gets
thick. It's like trying to suck a cold, thick milkshake through a
straw; you've all done that. The pump cannot create more than an
absolute vacuum, and if the oil is too thick the pump won't get much
and so the engine won't get it either. The cylinders don't mind
getting little, but the bearings need lots and so does the cam. Idling
too fast will cavitate the pump, delivering no or too little oil.
Idling too slow will throw too little oil on the cams and into the
cylinders. Can get tricky.

More likely damage is burning out starters from long
cranking. Or overpriming and flooding the engine. Or having it run
only briefly and quit, whereupon those cold sparkplugs will frost over
(H2O in the combustion byproducts) and the frost shorts them out. No
more spark. Burn out the starter trying to make it go. Starters have
no cooling system. Starter manufacturers say that a five-minute
cooldown is required after three ten-second cranks.
Kill the battery, and as the acid turns to water as it
discharges, the battery will now freeze (if it's cold enough and the
battery is dead enough and you leave it in the airplane) and split and
spill weakened acid everywhere. It'll still eat your airplane.

Cars typically use 5W30. I used to use 0W30 in my Ford
pickup. Started OK at -35°C. Airplane engines can't use such thin
stuff.

Dan

Matt's answer is right on.

Ah, yes, the annual "Is it necessary to pre-heat?" thread. Soon to
be followed by the "Should I leave it plugged in all the time?"
discussion!

Just to get the ball rolling, we pre-heat Atlas whenever the temp is
below 40 degrees F. And, yes, we leave it plugged in all the time.
("It" being a Tanis oil pan and cylinder head heater with a quilted
nose cowl wrap to hold the heat in...)

Here's a pic of our cowl wrap, custom made by Mary from an old nylon
sleeping bag and a bunch of velcro:
http://tinyurl.com/2oj9g7

We fly at least weekly, so I don't worry about condensation. IMHO,
plugging in the heater immediately after shut-down should help to
prevent condensation from developing, since the engine never cools
back to ambient temperature before it's started and brought back up to
temperature at the next flight.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Hi Jay!

Kinda feels like the other "home" doesn't it !?



Dave



On Wed, 19 Dec 2007 16:57:53 -0800 (PST), Jay Honeck
wrote:

Matt's answer is right on.

Ah, yes, the annual "Is it necessary to pre-heat?" thread. Soon to
be followed by the "Should I leave it plugged in all the time?"
discussion!

Just to get the ball rolling, we pre-heat Atlas whenever the temp is
below 40 degrees F. And, yes, we leave it plugged in all the time.
("It" being a Tanis oil pan and cylinder head heater with a quilted
nose cowl wrap to hold the heat in...)

Here's a pic of our cowl wrap, custom made by Mary from an old nylon
sleeping bag and a bunch of velcro:
http://tinyurl.com/2oj9g7

We fly at least weekly, so I don't worry about condensation. IMHO,
plugging in the heater immediately after shut-down should help to
prevent condensation from developing, since the engine never cools
back to ambient temperature before it's started and brought back up to
temperature at the next flight.

Jay Honeck wrote:
Matt's answer is right on.

Ah, yes, the annual "Is it necessary to pre-heat?" thread. Soon to
be followed by the "Should I leave it plugged in all the time?"
discussion!

Almost as much fun as the "does it hurt your engine to practice
engine-out approaches."

:-)

Matt

Four questions..

What weight of Oil?

What brand?

How long before the oil pressure came up?

How long since last run?

Preferred answers.

15/50, Aeroshell,less than 15 seconds, less than one week..

4 of 4.. no concern

1, 3 and 4 ...probably no concern

1 and 3, - might see aluminum spike a little in your next oil test

Single weight, brand "X", more than 15 seconds, more than 3 weeks..
Probably should not do this very often...

The above gleaned from others much more capable than I, and I chose
to listen when they speak..

YMMV!

Dave



On Wed, 19 Dec 2007 12:21:28 -0500, "Peter R."
wrote:

This time of year here in the Northeast US I always preheat my Bonanza's
IO520 engine with a Tanis heater and an insulated cowling/prop cover as it
sits in an unheated t-hangar. The result is that the oil temperature at
startup is around 105 degrees F, even if the outside air temperature is as
low as -15 degrees F.

Monday night I arrived at my t-hangar to discover that at some point during