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Correct Glo Engine Temperature??

Old 05-17-2004, 05:53 PM
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gary41
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Default Correct Glo Engine Temperature??

Having recently obtained a digital thermometer, I am courious as to what operating tempeatures would be considered "normal" for a two stroke glo engine.

Say, for example, a OS .61 ABN type. Anyone have any info on this subject?

Thanks, Gary
Old 05-17-2004, 06:53 PM
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William Robison
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Default RE: Correct Glo Engine Temperature??

Gary:

There is no right or wrong temperature. You can record yours to indicate a possible change when you get a variation, but that's about it. Further, the head around the glow plug will be one temp, checking the fins on the bypass side will give a different temp, and the muffler/exhaust stack will be different again. Accepted point of measurement is as close as you can come to the glow plug. Acceptable range for me is 225F to 300F. Colder or hotter still doesn't mean there's a problem, though.

If you find you're at 350F or higher I strongly recommend your use of a castor oil blend, it has to be hotter inside and the synthetics don't work when the temp gets up there.

I have a Raytek thermometer, I got it for checking cylinder balance on racing cars. The only use I make of it for single cylinder model engines is during break-in, to be sure the engine is neither too hot nor too cold. Its greatest use in modelling is again, cylinder balance checks on multi-cylinder four stroke engines.

Bill.
Old 05-18-2004, 12:04 AM
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Default RE: Correct Glo Engine Temperature??

I agree with Bill...there's no specific right or wrong temp and a temp guage is really only useful for doing comparative checks when you change fuels or plugs etc. or to compare different engines using the same fuels. One of the problems with the infra red type is that you'll get a different reading from a shiny surface than you will with a matt black surface even though the actual temperature is the same. The common thing between all engines though is at the base of the glowplug where the machining is all much the same and the thickness of the metal is the same. I'd also agree with Bill that 300F would be an upper limit, in fact if I saw that with a thermocouple I'd be stopping the engine and finding out why it was so hot.
Old 05-18-2004, 07:02 AM
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Cyclic Hardover
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Default RE: Correct Glo Engine Temperature??

Sorry to inform you that you are one of the hundreds of RCers who bought this piece of---which their are no specifications to go by. Call it a working "widget." I sure those who came up with this thing are sitting back laughing and raking it in. One clear indication of a hot engine is when you lose power and land with the throttle full open and you barely moving most often cause by a lean running engine.
I would be embarassed to admit I had one even if it was given to me.
Old 05-18-2004, 08:25 AM
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Default RE: Correct Glo Engine Temperature??

Unfortunately this is an infrared thermometer and as such only measures the heat radiated and transforms it into an approximate surface temperature. It is only accurate if the surface is not reflective and approximately 15% grey. It will give higher readings for a black engine such as a Saito Black Knight, and lower readings for a polished engine, such as say an older polished Fox engine. The actual surface temp will also be lower than the reading if it has a large fin area, and higher if it has a small fin area. There will also be differances between cowled and uncowled.

That said the readings don't vary as much as the above would lead you to believe. Although no one can give you a good go-no-go temperature to start with, it is good to quickly set the engine if you have expermented by taking readings of known rich and lean setings, providing that you are sure you are not reading the exhaust temp. This can happen if you take the reading from the exhaust side and you thermometer cannot resove accurately enough.
Old 05-18-2004, 09:38 AM
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Bax
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Default RE: Correct Glo Engine Temperature??

Depending upon the type of temp gauge, engine temps can vary quite a bit. I've personally measured an O.S. Max .40 FP turning a 10 x 6 MAS prop with a contact probe. We measured at the cylinder head just above where it joined the crankcase (It's very smooth there), and at the rear, where airflow is stagnant. We measured 375 degrees F. The engine was running normally, just rich of peak RPM on Omega 15% fuel. That engine went on to have many hours in our shop trainer.

Except for just on top of the exhaust port, that spot is likely to be just about the hottest part of the engine.

bax
Old 05-18-2004, 04:53 PM
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gary41
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Default RE: Correct Glo Engine Temperature??

Thank you all for your input on my temperature question...FYI, the temp probe is a thermocouple type (an accessory to a digital multimeter)

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