Warning

My Feedback: (5)

Im new to tuning my engine and how hot should a glow engine get?


And to me i seem to get my engine to run great but the engine seems to be pretty hot?

Is that alright ???



Thanks for the help everyone!

RaceCity

Engines get hot. There are no published guidelines for operating temperatures of any specific glow engine because of the large number of variables that would influence this.

Did you just get a temp gun? Take it back and see if you can exchange it for a good tach..something useful.

Learn to tune your engine by ear and by tach. When you are satisfied it is running properly you can take some temperature readings and record them for future use with THAT engine/installation. It will not be useful information should you change engines, installations, etc.

Temp guns are pretty useless for our purposes in the grand scheme of things because we don't know what we're looking for.

Stubshaft

Run the engine at full throttle, and at max power settings DO NOT go over 200deg.measured with temp gun at the head. Use the temp gun in conjunction with tach (with 200 deg. as max lean temp.), and you should be able to find the best power curve/fuel setting. This will also tell you if engine is lugging due to improper prop selection or overrevving.

Cyclic Hardover

My Feedback: (3)

PLease do a search on Temp guns or indicators. We go through this every two weeks. There are no published specs on temps for glow engines. They get hot. If you touch it and burn your hand then don't touch it again! If it gets too hot, you'll know it. There is a 90% chance that your engine will lose poser slowly and or quit running while in flight.

Temp guns are cool but if anybody tells you a temp range, I suggest you ignore it and any other advice

Not24

My Feedback: (1)

200 degrees is a joke. They get that hot at idle. If you are worried about running too hot, use a fuel with some castor in it for insurance. You can use a temp gun for reference only. I did, and learned a little about prop sizes and nitro content. Every engine will be different.

proptop

My Feedback: (8)

Just out of curiosity I got one of those little "Dura Trax" temp. checkers (for want of a better term ) for 20.00

I walked around...up and down the flightline...checking various engine temps...

Just as a rough estimate, I would say that below 200 is too cool...and above 300 is too hot...(how's that Cyclic?)

I checked an O.S. 1.08 blubbering rich during break-in at 110-130 degrees. And I checked a TT .46 screamingly leaned right out at 350+ [X(] shortly before it sagged...and it was smoking hot after shut down.

Somewhere around 250 plus or minus should be o.k. if you want a number.

The car guys get nervous when you talk about anything close to 300

If you have one, you need to check the settings of the device to be sure it's adjusted for either a shiny surface, or a sand blasted/glass beaded surface, etc. etc. because that can effect the readings, and that can change from surface to surface, like a polished head, vs. blasted case, etc.

They're fun to play with...but as you gain experience, you can tune by "feel"...meaning by the sound, and smell, and just a general feel for things...and how it sounds while flying.

Cyclic Hardover

My Feedback: (3)

A temp guage tells you something you cannot do anything about because your in the air when it happens. It's a stupid tool for RC purposes and does absolutely nothing. If you took a reading after it landed, it would still be way off from actual flight. If you took a reading before you took off, you should not let anybody know that you did.

If you went through the expense of an onboard data system hooked up to some form of a themocouple, then you can reap something positive from it all. Plus the 100 different flying conditions and props , loads etc that can change the temp

downunder

I agree they're a useless tool if you just want to use it to tune an engine. Their only real use is to find out things just for interest's sake and to get comparative readings (after you're used to how an engine runs normally) when you make some sort of change like a different fuel, prop or maybe putting the engine inside a cowl. But even then you have to tune as you normally do either by ear or with a tacho.

The normal temps of engines varies so widely there can't be any hard and fast rule. With one ABC engine I had it running at 145F in a slobbering 4 stroke then at 300F fully peaked out. This seemed far too hot for my liking so I richened it until I had an audible drop in revs but the temp only dropped to 295F. It was quite happy. Another time I was running a very old OS Max II which was sounding (and smelling!) quite unhappy at 295F because silly me was using the wrong fuel. I changed the fuel and the temp immediately dropped to about 240F.

I use a contact thermocouple though and always check temps at the base of the glowplug on the head itself because that's a standard distance from the centre of the combustion chamber and no cooling fins to give a false reading.

DarZeelon

Joe,


This is bologna! Water boils at 212 degrees; do you think methanol will burn at a lower temperature?
In full size aircraft, the exhaust gas temperature (EGT - determines the correct mixture setting) is important.
But head fin temperature???

A temperature gun will not tell you anything you need that you cannot know without it.
Don't waste your money on this useless instrument!

As long as RPM rises as you lean the high-speed needle, the temperature is right.
When RPM begins to sag, it is starting to be too hot.

That's it! If it runs right, the exact head fin temperature is the most useless info you can find.

Did you notice R/C people were better at everything, before all these useless gadgets became available?

Sport_Pilot

Temps of good running engines often run well over 250 degrees. Your recommendation would result in an over rich engine on most installations. Especially cowled engines.

Sport_Pilot

If you convert a glow engine to gas they will exceed 300 degrees, maybe even 400. Yet no harm is done. It's not the temp but the lack of lubrication that does our engines in. You can set the carb better with a tach, so a temp gun is not required. For cars and heli's there is no convenient way to check the speed, so heat guns are usefull if you know the normal temp for that application.

DarZeelon

Hugh,


I beg to differ here.

It is true lean-runs will kill engines. But a lean run is not a case of insufficient lubricant, but a case of over-advanced ignition.

Since a lean mixture ignites sooner and burns faster than a rich mixture, over-leaning the mixture will cause the maximum burn pressure to occur too soon and the onset of detonation...
This will cause the piston and other parts to overheat and expand, increasing friction and also causing the oil to break down.

And there you have it; not a lack of lubricant, but the results are the same...

Sport_Pilot

I said lubrication not lubricant. Oil breaking down is lack of lubrication. As is too little oil. The mineral oils used in gas engines do a better job of lubication at high temperatures.

DarZeelon

Hugh,


This is correct, but the lubrication problem results from the friction, that results from the piston growing faster than the sleeve.
This friction breaks down the oil, since there is no room for the oil-film between the parts.

Heat causes the friction, which breaks the oil down and causes still more friction and heat...

The problem at the base of all this is the relative lack of fuel; not of lubricant, but the end result is the same...

Sport_Pilot

Ahh! Sorry but the piston doesn't grow faster than the sleeve. When an engine is running hot the compression drops off because of the sleeve growing faster than the piston (with the exception of well designed ABC). It is the fact that lean runs offer less oil and the extra heat from the lean run breaks down the oil that does the engine in, not the temperature. They run much hotter when run on gas, without siezing. Now, maybe not as hot as a gross lean run, but a lot hotter than the 250 or so that we run glow fuel at. Most so called siezed engines quit from severe detonation, not siezing.

Not24

My Feedback: (1)

Hey guys, I used a temp gun while testing my g2300. I used it for information purposes only, not for setting the needles. It was interesting to learn that the temp went down with a bigger prop, and down again with higher nitro. Does that mean I run the bigger prop? No. I select my prop size based on performance. I do run the higher nitro, also due to increased performance, but now i know that the higher nitro isn't making the engine hotter.

By the way. I already had the temp gun. I use it on horses feet to see if they are eating too much grass or not. Too much grass, and their feet get hot, and pretty soon you'll be calling the vet. This is really important on older horses, especially in the spring.

You learn something new every day!!!!

Cyclic Hardover

My Feedback: (3)

"BOLOGNA!" PLEASE RESIST THE URGE TO CURSE OR FLAME!

You know, the thing is we have the technology and the brainpower and the idea of it all is very good. I mean we all would like to know the limits of our engines but the best we have so far is rpms but even that is weak. RPM limts are important on 4 strokes but the doors are wide open on two strokes. I have a 46pro for a few years now on that Shrike 40 of mine. I forgot but what are the published limits, 12-13000? I run a 9/7 at 17000rpms on this abusing the *&^% out of it and it's still going.

Not24

My Feedback: (1)

Cyclic, you talking to me?

If so, I don't understand. I think we are on the same side of this one.

DarZeelon

No, Eddy,

Cyclic is talking to me...

...That is, unless this two-stroke has dirt cheap, 'shopping cart' type, 5,000 RPM limit bearings, like some lesser OS clones (and perhaps some originals too, lately...).

BTW, some Kyosho props also have a 13,000 RPM limit... Check the Tower site where they're listed...

Sport_Pilot

Keep in mind that nitro will run hotter when leaned out. If you are running high nitro a lean run will cause it to be even hotter than when running low nitro. It does run cooler at peak power and richer, but that is because nitro can burn without air and produces more power the richer it is.

Cyclic Hardover

My Feedback: (3)

Well, we both own Vettes?

bigbadbowtie

Not myself... I don't even own a temp gun. I did however have someone temp an HPI engine that I had running in a savage after a 5 minute heat race... 315 degrees. The same guy check it 4-5 times that day and freaked everytime he did it. He must have told me 25 times that its too hot and Im going to fry it. That engine ran great. I think I put close to 6 gallons of fuel through it and sold it running in an 1/8 scale buggy. I ran Morgans Omega 25% through that engine.