Preheating engines: Airplane engines versus auto engines

"Matt Whiting" wrote
news

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!

As a 6 year-old mechanical engineer of some 30 years practice and owner of
an IO-540 equiped airplane, I find it somewhat disturbing that the OP was
NOT a joke.
Anyway, pat on the back - big hug time for the courageous aviator who
started his engine at **GASP** 25 F, after careful deliberation on aborting
the flight until Summer.
Catch my drift??

I purchased Fat Albert from an FBO who kept him in an unheated hangar
for 40 years, and never preheated unless it was well below zero
(that's in Farenheit, sonny)... Often it was a 3AM panic call from GM
who needed engine parts delivered to avoid the assembly plant from
shutting down and their truck was already on the way to the airport
with the parts....Load the plane, start the engines, hurry down the
taxiway checking mags while rolling, swing onto the runway, cob the
throttles and go... Elapsed running time from start to takeoff, less
than two minutes for the nearest runway, and perhaps three minutes for
the furthest... HIs engines routinely went to TBO...

While there is nothing wrong with preheat, etc. - there is also
nothing wrong with using synthetic oil and preheating only for extreme
temperatures... The biggest killer of aircraft engines is dry starts
from weeks/months of sitting between starts... Low temperature starts
on a well oiled engine have little to no impact on the wear cycle...
I use 15W50 in the winter and 100W+ in the summer... I do not preheat
unless it is below zero F... My starboard engine has 1700 hours since
factory zero and other than the oil burn being ~ 3 hours to the quart,
it starts and runs like a new engine... The port engine has 900 hours
since a field overhaul and it runs fine...

denny

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?

--
Peter

Lycoming says you can start without preheat down in the teens if you
use multiviscosity oil. As others have said, one of the biggest
differences from auto use is that aero engines are often flown less
frequently so there's less oil hanging around at startup. On the
other hand, that's true even in warm weather, though warm oil will be
redistributed more quickly.

I doubt that you did any harm. Convert all the degrees to Kelvin
temps and be comforted :-)

On Dec 20, 6:04 am, Denny wrote:
The biggest killer of aircraft engines is dry starts
from weeks/months of sitting between starts...


That's one, but there's another bad one: Short flights,
especially in cold weather. byproducts of combustion include water
vapor, and some of that squeezes past the pistons and rings when the
engine is cold (some when it's hot, too, but much less so) and this
vapor condenses in the crankcase and ends up in the oil. If the engine
doesn't get hot enough for long enough, the water isn't boiled off and
will mix slowly with the oil, breaking it down and combining with
sulfur and chlorine and nitrogen to form sulfuric, hydrochloric and
nitric acids. These don't belong in your engine. The stuff that's left
from these reactions forms sludge and clogs up hydraulic lifters and
cakes on the inside of the case and soon enough breaks off and shows
up as scary black guck in the filter. The acids cause dissimilar metal
corrosion between the crank and cam and their bearings, between the
aluminum piston and the steel cylinder and rings, and on valve stems.
Bad. Corroded valve stems break and the engine tries to eat the valve
heads and gets indigestion.
The oil in my little old Continental doesn't get above
120°F on cold days. There's a tank blanket that I need to buy or make
to get it up. I just finished rebuilding the thing to fix corroded
bearings and seized valve lifters.

Dan

On 12/19/2007 7:56:55 PM, wrote:

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.

Thanks, Dan, for the education. Unlike some of the hotshot pilots in this
group who apparently were born with this knowledge, I admit to still having a
lot to learn despite flying twice to three times every week.

--
Peter

On 12/19/2007 9:40:19 PM, Dave wrote:

What weight of Oil?

20w-50

What brand?

Exxon Elite

How long before the oil pressure came up?

Within a minute or so, I don't remember now.

How long since last run?

This was Monday, aircraft last flown previous Saturday. Aircraft is flown
twice to three times every week.


--
Peter

On 12/20/2007 9:24:28 AM, Paul kgyy wrote:

I doubt that you did any harm. Convert all the degrees to Kelvin
temps and be comforted :-)

Ha. Thanks, Paul.

--
Peter

On 2007-12-19 12:21:28 -0500, "Peter R." said:

Given any other day, I would have plugged the aircraft back in and scrapped
the flight

I know what I did has negative long term repercussions on my engine's health

I'm sure you must do some analysis in your head to judge the damage
inflicted on the engine in this case - otherwise, how could you judge
if scrapping a flight is the appropriate thing to do? I'm curious how
you quantify the 'long term repercussions'. Have you concluded, for
example, that not preheating in this case will:

- Reduce the TBO for your engine by 10 hours?
- Increase oil consumption by .2 qt/hour?
- Increase the risk of a catastrophic in-flight failure by 5%?

Clearly those are just some examples, but I would like to understand
what you have judged the impact of flying in this case would be.

"gpaleo" wrote in message
news:1198154485.901022@athprx03...
"Matt Whiting" wrote
news
No, 6 year-olds should be in school by mid-day, not playing on mommies
computer!

As a 6 year-old mechanical engineer of some 30 years practice and owner of
an IO-540 equiped airplane, I find it somewhat disturbing that the OP was
NOT a joke.
Anyway, pat on the back - big hug time for the courageous aviator who
started his engine at **GASP** 25 F, after careful deliberation on
aborting the flight until Summer.
Catch my drift??

Perhaps with your extensive and pontifical experience you cold summarize the
findings of Shell, Chevron, and TCM of the percentage of wear that occurs in
the first 30 seconds of cold (ie, below 40 degrees) starts?

"Peter R." wrote in message
...
On 12/19/2007 7:56:55 PM, wrote:

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.

Thanks, Dan, for the education. Unlike some of the hotshot pilots in this
group who apparently were born with this knowledge, I admit to still
having a
lot to learn despite flying twice to three times every week.


FWIW - http://www.reiffpreheat.com/tbo.htm

And some magazine articles at
http://www.reiffpreheat.com/product.htm#Why_preheat

And a blog article about engine moisture after shutdown (and follow-up) at
http://www.reiffpreheat.com/product.htm#Why_preheat (2nd and 3rd down)

As always...YMMV.
--
Matt Barrow
Performance Homes, LLC.
Cheyenne, WY