Air cooled engine in cold weather ?

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Originally Posted By: Surestick
Originally Posted By: boraticus
There's quite a bit of difference between an aircraft cruising at 180 mph or more in -40F temperatures and a lawn tractor working relatively hard pushing snow.

We're not breaking new ground here. Engines are designed to perform certain tasks. Engineers build in components/characteristics for them to perform and survive. I doubt very much that throwing a rag over the cooling air intake would be considered as being innovative engineering. Particularly when a seat of the pants thermometer is being used to measure engine temperatures.

Sack the sack.


Most air-cooled piston-powered airplanes don't fly high enough to be at -40C temps, those that do actually tend to have cooling issues due to the thinner air not carrying as much heat away.

Most air-cooled piston-powered airplanes also have a winter-kit that restricts cooling air and is used in colder locations during the winter.


I'm having a bit of a problem making the leap from airplanes to lawnmowers?

The similarity eludes me. Sure, both might use air cooled engines but they're worlds apart in their application.
 
Originally Posted By: boraticus


I'm having a bit of a problem making the leap from airplanes to lawnmowers?

The similarity eludes me. Sure, both might use air cooled engines but they're worlds apart in their application.


If you go back to my original post, that was actually the gist of it. The aircraft have sensors to regulate the temp whereas a snowblower engine doesn't (and by the way, aircraft are most prone to overcooling at low altitude during the descent to land, not at high altitude cruising because the air is thinner up there and the engine is producing more power than when descending).

But I think he does have some legitimacy. The same engines get used in mowers that operate in 100 degree ambient with their intakes clogged with grass. Most small engines have such a huge cooling margin that thin burlap isn't going to roast it. And also if it IS an old Kohler K-series, you can pretty much totally obstruct the stationary screen and it will still suck cooling air in thru the gap between the back of the screen and the flywheel where there's a rotating screen.
 
Originally Posted By: 440Magnum
Originally Posted By: boraticus


I'm having a bit of a problem making the leap from airplanes to lawnmowers?

The similarity eludes me. Sure, both might use air cooled engines but they're worlds apart in their application.


If you go back to my original post, that was actually the gist of it. The aircraft have sensors to regulate the temp whereas a snowblower engine doesn't (and by the way, aircraft are most prone to overcooling at low altitude during the descent to land, not at high altitude cruising because the air is thinner up there and the engine is producing more power than when descending).

But I think he does have some legitimacy. The same engines get used in mowers that operate in 100 degree ambient with their intakes clogged with grass. Most small engines have such a huge cooling margin that thin burlap isn't going to roast it. And also if it IS an old Kohler K-series, you can pretty much totally obstruct the stationary screen and it will still suck cooling air in thru the gap between the back of the screen and the flywheel where there's a rotating screen.


An air cooled engine can operate a temperatures up to 300 deg. F or more. If on a cool day, it's operating at 200 or 225 degrees, what would be the harm in that? I'd rather have a machine operating in the 200 to 225 degree range than 300.

In addition to the above, if the burlap bagger doesn't even know what temperature the engine is operating at, how would he know if what he's doing is beneficial or not?
 
Originally Posted By: quint
FastGame, whatever you end up telling him, dont let this friend of yours join BITOG. This is an OCD-free forum, it does not need crazies like him polluting the place by second guessing the manufacturer with DIY shadetree re-engineering and stuff. No one here does that kind of thing.
lol.gif



Actually the guy is a Master Machinist (precision tool & die) who works at an experimental plant for GM. He does invent some things that are cool, but this burlap flap was a crack-up.

He already knows about BITOG and has no intentions of joining.

Sorry for posting crazy stuff, I won't do that again.
 
Originally Posted By: boraticus

In addition to the above, if the burlap bagger doesn't even know what temperature the engine is operating at, how would he know if what he's doing is beneficial or not?


The same way half the people on here will say, "I just changed from brandX 5w30 to brand Y 5w30 and my car REALLY likes it better! Its smoother and quieter so I know it has to be working SO much better."

Actually, he's probably got more real information than that by far. If the burlap bag keeps him from developing carb ice, then he has an objective measure that its helping.
 
If he's just blocking air from the front of the motor, I don't believe it's doing much. When it's cold enough to snow, cold air will surround the motor and blocking 1 source won't help much.An air cooled motor will run cooler in cold weather then when it's 80 out. If it was a water cooled motor blocking the radiator would make it run hotter, but and air cooled mower motor also has a fan that's going to be blowing cold air directly on the motor to keep it cool.Blocking the air intake for that, would make it run hotter.,,
 
My Cessna aircraft has a "winter kit" that restricts the cooling air to the engine by about 50-60%. Cylinder head temps are still lower in winter (up North) with this kit installed.

However, I'd never use a cooling system modification without valid data to see and understand what the results are.
 
Originally Posted By: BigCahuna
Originally Posted By: boraticus
"Blocking the air intake for that, would make it run hotter.,,"

Would you like a bag for that sir?


What works better, paper or plastic?.,,


Apparently...... burlap.

Same material as my wife's pajamas. But, that's another story.
 
Originally Posted By: Trav
....What about a VW beetle or Corvair? They ran in all seasons without restricting the air flow in cold weather.


Actually, the beetle had a thermostat, connected Via a rod to flaps on the cooling shroud. The bellows type thermostat would contract when cold and close the flaps until the engine warmed up. You rarely saw them because most people didn't understand how this system worked, or felt it wasn't needed ( It was needed..), so they removed them.

AS for his "sack" At most, the engine will run maybe 70-80 degrees cooler in the winter than in the summer. This assuming summers are 80 degrees and winters are 0 degrees. Temp is temp. Feels like a big difference to you and I, but the engine only See's the air being cooler than the hottest summer day it is used.
 
I was under the impression that the VW had that apparatus to capture air from the engine to heat the inside of the car?
 
It's been a long time, but I remember having to run at partial choke for a LONG time in below freezing temperatures on my GSX-R750. But it had a very large oil cooler and oil jets aimed at the bottoms of the pistons and tops of the combustion chambers.

My GPz550 had no such problems.
 
Originally Posted By: atc250r
Air cooled engines are well known for "over-cooling" in Canadian winters. I wouldn't say you're friend is on crack, but he should get one of these if he's really concerned about engine temps...

https://www.denniskirk.com/trail-tech/14mm-spark-plug-temperature-meter.p408666.prd/408666.sku


That looks like a useful device. Wonder how well it will fit in deep spark plug holes? Might be a bit of a challenge to squeeze the sensor and the socket into holes on engines with deep set plugs.

However, if one is using a burlap thermostat, he may as well get a long mercury thermometer, drill a hole in the engine housing to rest the end on the cylinder/head and stick it up through the engine cover. Might be a bit hard to read. The numbers on those things are pretty small. I guess, while he's at it, he could mount some kind of magnifying glass in front of the thermometer.

No end to the possibilities for the creative....

Personally, I think the burlap idea is crazy. I'd go with a nice Harris tweed in a matching colour tartan weave from Scotland...
 
What IS the relationship between air temperature and engine temperature in small air cooled engines? I mowed our lawn today at 33 degrees. It took 3 pulls to start, but it ran perfectly for the 3 hours it took to finish. And then I dump some stabil in it, and put it up for the winter.
 
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