Engine temperature, what should they run

[customcover]

I am running 2-BME twins, 102 & 110 When I check the temperature what is a safe range to be in.

Thanks

[Al Lewis]

You may want to PM Tired Old Man (Pat Roy) on this one buddy. I believe he has quite a bit of time with these engines and would know exactly what temps they should be running.

[Tired Old Man]

Try to keep the max below 300 with a BME twin. They can go a bit higher but due to the minimal case mass and fin area they heat up and retain heat rapidly after the 300 mark. Normal running should start around 225f, plus or minus a few degrees.

[customcover]

Thanks, Tried Old Man

I knew someone would know the answer. It's great to have the resources of FG.

Thanks, again

[exeter_acres]

Are the above temps measured with a sensor while in flight or just after landing?

I would think those two numbers would be very different..

[STLAV8R]

	Quote: Originally Posted by Tired Old Man
	Try to keep the max below 300 with a BME twin. They can go a bit higher but due to the minimal case mass and fin area they heat up and retain heat rapidly after the 300 mark. Normal running should start around 225f, plus or minus a few degrees.

Is that in flight or after landing? If the minimum is 225f, what is the max?

[Tired Old Man]

In flight temps. Post landing temps are meaningless.

Anyone care to guess how much an engine cools during a low throttle descent or after a few pumps of the throttle stick during a low power descent? I've done a lot of work in this area and I can drop the CHT over 175 degrees on a short approach. On a long approach I can get the CHT to below 100f. So if I taxi back and aim a temp gun what did I learn? Perhaps how much it would heat up during a taxi but I won't ever have a clue about what the engine did in flight, where it did all the work.

Without an active in flight temp monitoring tool you don't have a clue to what's going on with operating temperatures. I won't even try to tune an engine that hasn't yet reached at least 185f. To do it colder maens that tune and idle settings will be different as soon as the engine reaches an effective operating temp, which kicks in around 100c, or 212f.

[reyn3545]

One of the best tools I ever bought was an Eagletree wireless transmitter. I was suprized to find out how cool the motor ran during flights (just sport flying) but as soon as I chopped the motor for the final turn, the temps started to climb. Then, by the time I was on the ground and had taxied up to where I could read the temps with a laser gun, the temps typically have dropped by 25 or 30 degrees.

It's also a great tool for monitoring prop speeds.... amazing how much they unload in the air.

[customcover]

So in other words, all of the temp guns many of us use are worhtless. Or should we be adding an additional 25 degrees when we check right after landing?
Would like to know of any other option other than purchasing another piece of equipment and installing something else in our planes. The only reason I ask is because like many of us out there I just paid a good hunk of change to have a motor rebuilt.

Thanks

[Jedijody]

	Quote: Originally Posted by customcover
	So in other words, all of the temp guns many of us use are worhtless. Or should we be adding an additional 25 degrees when we check right after landing? Would like to know of any other option other than purchasing another piece of equipment and installing something else in our planes. The only reason I ask is because like many of us out there I just paid a good hunk of change to have a motor rebuilt. Thanks

For the most part and in the way they are used yes, the infrared temp guns are useless. The temperature of our engines can change much faster than one would think. It could be the temps your engine hit 5 minutes into a 10 minute flight that does damage, damage from high temps are also cumulative. Your engine can easily drop 50-100 degrees on a down wind leg and landing approach then taxi back to the temp gun.

For an inexpensive and accurate means of seeing the high temps you're hitting in flight get a thermocouple temp guage from Venom racing. You can also use them to see what high temp your engine will hit in a single specific maneuver. They are also less expensive than many infrared temp guns. Use the search function in this forum, there has been much discussion on them here before. A member here, RTK, is also a very good source for info in these useful tools.

[Albatross]

This is an example of inflight twing engine temperatures + baffling (check the temperature plot at the bottom of the page):

http://www.geistware.com/rcmodeling/...es/baffles.htm

Would be interesting to know how these temperatures are doing by now as this engine is fully break-in.

I removed the Eagle tree data logger; I need to put it back. I will make some room in my schedule to put install this device back to the airplane; I will let you how it works.

[Tired Old Man]

You can add whatever value you desire to the temperature obtained from a temp gun and still know absolutely nothing about what temps your engine achieves in flight. The defination of useless is "having no value" so you cannot modify a result to obtain something useful. Good for R/C cars but a waste of money for planes unless all the running is done on a bench.

So temp guns for planes equates to useless, of no value or benefit, and never to be used for determining flight temps. Hopefully that clears up any contemplation of using a temp gun for checking airplane engine temps. Eagle Tree in flight telemetry for the best and Venom data logger for a peak and a low.

[reyn3545]

I don't want to discredit the use of a standard temp gun, it's certainly better than spitting on your cylinder head to see if it boils! Your motor isn't going to cook if it got to 300 degrees for 10 seconds, it's going to cook if it stays there for a while. If you only measure it once you taxi up to your pilot stand, you're probably not getting the hottest temp.

the Eagletree (or any other) monitoring system will give you detailed info about a lot of things going on in your motor, power system, servos, etc.. I like to put it in a new plane, use it while I'm working with baffling needs, etc.. then take ti out and put it on the shelf.

[ljaganna]

After reading some of these threads I went ahead & bought the Eagletree wireless telemtry system. One of the best purchases I made. It cost around ~350-400 for the 1st system, but their sensors are inexpensive, so I bought a whole bunch of the thermocouple & rpm sensors, and just put the eagletree's in flight recorder/Tx on velcro so I can move it from plane to plane in 20seconds. So this ended up being a great value....to get wireless telemetry on 5 planes for $500.

I've learned a lot with this system, especially about how useless the infrared guns are. Looking at in flight prop rpms & battery voltage was very useful also.

The Eagletree wireless telemetry systems are a great investment for any giant scale hobbyist.

[reyn3545]

Yep... I bought it back when I was running a Futaba radio system and wanted to know more about receiver temps (I won't go into the "problem"... it was amazing to find out how fast a plane can heat up just sitting out in the sun, how cool they run in the air with just a little airflow in the fuse, and how fast they heat up again... haven't left a receiver of any brand exposed to direct sun since then!