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HomeRC & PowerAircraftHelicopterEngines Plugs Mufflers Fuel › OS 50 Hyper cylinder head temperatue
04-22-2009 07:04 PM  9 years agoPost 1
Tolla

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Cape Town, South Africa

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Can anybody tell me what the maximum cylinder head temperature should be on the os 50 hyper. I have a sesor mounted on the head at the glow plug so I routnely measure up to 200*C. Is this normal?
Why I ask, is because when I look at the instructions for the 'Carbsmart', their maximum setting is 140C* or so, and most pilots set their carbsmart to be around 100*C. No ways can my motor run that cold.
I am not asking how long you can hold your finger on the backplate or what you infra red gauge measures upon landing.

What i am interested in is what other pilots motors cylinder HEAD temperatures are doing during flight. Can I run my motor at 180*C without damage? What was teh motor designed to run at?

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04-22-2009 08:15 PM  9 years agoPost 2
AaronJohnson

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mason,MI

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WOW that is hot. I run my Carbsmart at 110C. I have never heard of anyone running there hyper that hot. Do you really mean 200 CELCIUS??? With mine running at 110C I have 10 gallons thru it and no bearing troubles, has great power, piston and ring look perfect. It runs about 1 18 turn out usualy on CY 30% fuel.

IMO you shouldnt have the hyper running any hotter then 110 C or maybe 120C at the glow plug. Any hotter just causes damage/shortens the life of the engine.

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04-23-2009 01:52 AM  9 years agoPost 3
airdodger

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Johnston USA

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http://www.flyrc.com/articles/tune_your_engine_2.shtml If you run the engine hot, but not to the point where they are damaged what would you think would shorten it's life? Keeping in mine they are heat engines and designed with that purpose in mind. The more heat the more power derived.

Chris

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04-23-2009 02:44 AM  9 years agoPost 4
AaronJohnson

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mason,MI

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From that article.
There's a risk of: the ignition point advancing; additional temperature rise; leaning of the mixture; detonation, and engine damage.
Heat plays a critical role in the ignition timing of a glow engine. Too much heat= too much timing and that is bad. My hyper doesnt run anywhere near that temperature and nobody else's I know of runs that hot either.
The more heat the more power derived.
Not neccessarily. We need the proper amount of heat. Eventually you get to the point where things get too hot and cause detonation which kills power and detonation also kills the engine. When you lean the mixture, you make the engine hotter, meaning you make more power. What happens when you lean it too far? You dont make more power, you damage the engine. A cyl head temp of 200C on a hyper would lead most to think something is wrong. Maybe leaning out? Maybe the cooling system is inadequate? Wrong glow plug choice for the typer of fuel being run?

The reason I state that too hot can damage the engine is that it becomes more easy to burn the ring and/or burn the piston or piston shirt. Just my .02

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04-23-2009 03:27 AM  9 years agoPost 5
rocket_33

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Mount Pleasant, Michigan USA

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I think he is refering to it being 200 F not C because if it were 200 C that would be close to 392F. I don't think the engine could evenrun lean enough to get that hot.

If he is saying 200F that is equal to 93 C so in this case the engine is rich and can be leaned out a touch.

If you really think it is 200 C try touching it (and get ready for 3rd degree burns haha). Maybe your onboard data system is not calibrated correctly

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04-23-2009 04:04 AM  9 years agoPost 6
AaronJohnson

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mason,MI

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If you really think it is 200 C try touching it (and get ready for 3rd degree burns haha).
Thats what I was wondering. 200 C is really hot.

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04-23-2009 04:12 AM  9 years agoPost 7
RaptorMan23

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Sioux City, IA

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Im betting that his temp sensor wire is actually touching his piston sleeve in between the head and case. I know a guy that did the same thing and hes always getting temps around 350F, then whe we get a reading with a handheld, its around 200 when checked in the right spot

The temp guage wire is supposed to go on the first fin below where the head and case meet

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04-23-2009 04:25 AM  9 years agoPost 8
airdodger

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Johnston USA

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The temperature stated in the quoted article was 375 degrees but 400 degrees might be too much. I also stated a temperature that would not damage the engine. What I want to know is why a higher temperature would shorten the engine life. The more heat the more power, thats why nitro works it's a gas law of physics, as long as combustion defects don't arise. Heat does not necessarily cause detonation. The engine will make more power on a slightly rich mixture, you can check that on the web if you don't believe me. The engine combustion far exceeds the temperature that the piston would melt at but it does not melt, ergo a rise in head temperature does not translate to excessive temperature in the parts. This does not mean I think Tolla has a correct reading.

Chris

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04-23-2009 06:01 AM  9 years agoPost 9
Tolla

rrApprentice

Cape Town, South Africa

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Yes I mean 200*C. My sensor is attached to a small elecctrical connector and is kept in place by the glow plug itself. The connector replaces the plug washer in this case.Have been running some tests and that particular plug did seem to make the motor run much hotter than an o.s. #8 I tried on the next flight. Still, the #8 plug ran up to 160*C and I had heavy bogging and not much power. Touching the backplate always gave the indication of being within limits, though.

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04-23-2009 06:06 AM  9 years agoPost 10
rocket_33

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Mount Pleasant, Michigan USA

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Ah ok....I don't think that this is measuring the head temp as one would expect but rather you are seeing the heat transfer into the plug and I can understand how the observed temp would be higher than if measured with a probe in the same area as that used by the Carbsmart.

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04-23-2009 06:12 AM  9 years agoPost 11
Tolla

rrApprentice

Cape Town, South Africa

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Oh , let me add that here in sunny South Africa the summer temperatures are anything between 27-35*C, so that does not help. We are into our winter now and the other day I did notice that the head temp was much lower.Winter has now only started so I'll log some cold-day temperatures to compare. Maybe I should consider a more efficient cooling fan to help in our hot summers? Get more air over the fins, since blowing hot air over hot fins doesnt help much.

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04-23-2009 06:43 AM  9 years agoPost 12
Tolla

rrApprentice

Cape Town, South Africa

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Rocket-33
Okay, I'll move my sensor to where the Carbsmart sas to mount it, then i'll see whether my readings are more in the ballpark. Correct me if I'm wrong , but the sensor should be poshed right up to the combustion chamer and not just be between the fins?

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04-23-2009 12:02 PM  9 years agoPost 13
airdodger

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Johnston USA

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The sensor placement under the plug makes a big difference. The temperature will show faster and be a larger number. When I ran two strokes racing that was one place we measured from as well as from the exhaust, exhaust temperature is the best measurement because it shows so fast. The temperatures we ran at with the sensor under the plug was around 400 most of the time, but I saw 475 degrees F quite a few times. Above 475f the engine would still not seize but the top of the piston would be concave as opposed to covex it got so soft. If the internals of the engine still look fine I would not be concerned with the temperature readings.

Chris

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04-23-2009 03:27 PM  9 years agoPost 14
bbaxter

rrApprentice

Central Illinois

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You must set the engine for performance, and then see what temp you are running. If your engine is running properly, and performs well, then whatever temp you measure is "correct". Nobody can give you an absolute number because it will vary from day-to-day and if you change pipe tuning, fuel, rotor pitch, and so on. Temps can only be rough guidelines to tell you if anything's gone wrong.

The bottom line is that you must get the engine running properly by observing its performance...how it handles, how it sounds, and how it performs. THEN you measure the temp to see where you are.

Position of the temp sensor will vary so much from person-to-person, that you can only rely on it once you've gotten your engine running correctly. Then it can tell you if something's changed.

Over-reliance on temps to get engines set will shorten its service life, as we've seen all too many times in the service shop.

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05-31-2013 05:16 PM  5 years agoPost 15
datidun

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N Ireland

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Tolla how is engine surviving these days at that Temperature.

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