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Test stands for break in (not good)

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Test stands for break in (not good)

Old 05-13-2008, 09:55 PM
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RC Extreme power
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Default Test stands for break in (not good)

I know a lot of people think they need to break there engines in on a test stand or on the plane while not flying,

If you do this be care full and do not run for longer then a few min. at a time, You think that a lot of air is moving over the engine and cylinder but it is not, Most of the air is moving to the tips of the prop and not going over the engine, Plus most stands have a solid piece of wood behind the cylinder and air could not pass if it got there.

Even in the plane air is not moving over the cylinders and they will heat up if it is not flying.

I am rebuilding a engine now that was on a test stand and customer said he did not know what could have happened he just set it at about 3500 RPM and after 15 min. It just locked up, Well the cylinder and piston are cooked.

If you insist on breaking in with a stand or on the ground do it for short periods and let it cool between runs.

I will run maybe a tank through the engine while tuning and setting it up and then break it in where it will be running In the air


Milton
Old 05-13-2008, 10:32 PM
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Default RE: Test stands for break in (not good)

What engine is it?
Old 05-13-2008, 10:41 PM
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RC Extreme power
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Default RE: Test stands for break in (not good)

Ones that I sell, But put any engine under that condition and the same thing will happen.

Milton
Old 05-14-2008, 12:23 AM
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the Wasp
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Default RE: Test stands for break in (not good)

""But put any engine under that condition and the same thing will happen""

oh please, what condition, too lean ?, if you run it rich you wont have a problem !!
Old 05-14-2008, 01:36 AM
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Default RE: Test stands for break in (not good)

What a crock.
Old 05-14-2008, 06:08 AM
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Jake Ruddy
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Default RE: Test stands for break in (not good)


ORIGINAL: the Wasp

""But put any engine under that condition and the same thing will happen""

oh please, what condition, too lean ?, if you run it rich you wont have a problem !!

You should never run a gas engine rich... these aren't glow engines and all you do is foul plugs and stick rings.
Old 05-14-2008, 08:39 AM
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Default RE: Test stands for break in (not good)

Milton is correct. What he has seen with this engine is quite common, and the engine manufacturer doesn't matter. All can suffer the same fate. Few that run an engine on a stand for extended periods of time ever disassemble the engine and check the condition of the rings and cylinders after running. The vast majority just remove the engine from the stand and hang it on the front of the plane. They fail to notice that compression has dropped significantly, or if they do they might thnk that the lower compression was due to rings "breaking in". If they were to disassemble the engine they might find the compression loss was due to the piston ring beginning to stick at the exhaust port side of the piston.

Without cooling air additional to what the prop provides there is a good chance that the engine can be damaged by long runs on a stand. The prop does not provide very much airflow through the cylinders, and without having the air ducted through the cylinders the air from the prop has little cooling effect. Simply using the exhaust side of a shop vac with the hose directed to the side of the cylinder will provide much better cooling and permit long runs on a test stand. Monitoring the cht with a thermocouple and live data feed is also important. Temp guns are useless for even coming close to the actual cylinder temps.

I have the feeling that Milton's customer lied to him though. At 3,500 rpm it would have taken quite some time to cook the ring and coke up the engine. It was liklely run continuously at full throttle for quite some time. The oil and mix ratio selected will have contributed to the problem as well. As Jake noted, there is no point in running a gas engine rich.
Old 05-14-2008, 08:47 AM
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rmh
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Default RE: Test stands for break in (not good)

Experience
I have repaired broken engines ,broken airframes -broken battery paks
The common thread is the info provided must be carefully reviewed.
some people do provide usable info- regarding what happened to the item.
However when it comes to screwed up engines the reasons for the failure are often very "interesting"
Old 05-14-2008, 10:42 AM
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Default RE: Test stands for break in (not good)

ORIGINAL: Milton

Ones that I sell, But put any engine under that condition and the same thing will happen.

Milton
I was just wondering because I have run one of my Zenoah G62's (on a test stand) through several full tanks of fuel (32oz.) with no ill effects. I have since had it converted to EI and it is currently on my Giant Aeromaster. It flies like a bat of of h##l.
I am not saying a guy won't ruin an engine on a test stand and don't advocate doing it, I am just saying it didn't ruin my engine.
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Old 05-14-2008, 12:52 PM
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Default RE: Test stands for break in (not good)

""foul plugs""

you don't have to run it that rich !!!!

Jim
Old 05-14-2008, 12:58 PM
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Jake Ruddy
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Default RE: Test stands for break in (not good)

So tell me, just how rich is that rich? It doesn't take much... oil is either getting burned or building up.. there isn't much room in the middle.

Either way no sense arguing.. I dont even see the need for bench run ins anyhow.. throw it on the plane add Penzoil 50:1 tune it properly from day 1 and fly it. All this other stuff is a waste of time.

Next we will be talking about what oil to use again
Old 05-14-2008, 01:48 PM
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Default RE: Test stands for break in (not good)

2 strokes don't need oil, its in the gas
Old 05-14-2008, 02:02 PM
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the Wasp
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Default RE: Test stands for break in (not good)

I guess you didn't see that reply whereby the guy brakes-in his Zenoah G 80 twins on the bench by setting the RPM to 4000 and letting it set for a couple hours !!

"how rich" I ran my MVVS 35 about 700 RPMs below it's peak RPM on the bench, but I didn't run it to full throttle for a good 4 tanks,,

think about it, how much oil do you run in 5 gallons at 50 to 1, only about 15 oz, even less at 80 to 1, well in the 70s I ran 32 oz to 5 gallons in my Trials bikes, these are low revving engines and I very very rarely ran them over 15 MPH all day long, stop and go all day long and they never over heated never fouled a plug..

I ran my MVVS at 28 to 1 for the first gallon on the bench, then I leaned the mixer to 32 to 1 on the 2nd gallon on the bench,, 3rd gallon was 36 to 1 in the air, 4th gallon was 40 to 1 in the air..


""2 strokes don't need oil, its in the gas"" LOL Hughes LOL
Jim
Old 05-14-2008, 03:18 PM
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Jake Ruddy
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Default RE: Test stands for break in (not good)

It's just like an oil debate... some want to bench run them and some of us don't see the point. Thats 4 wasted hours when I could be flying it

Might also like to consider where Zenoah comes from.. its designed to take abuse which is part of the reason why they are generally heavier.. more material to help disapate the heat.

There are many rc engines that wouldn't stand up to that. They are designed to be light and powerful and require proper cooling. Just look at the fins (or lack of) and how thin they are.

My 60 has run from day one on 50:1.. 50+ gallons later still running like a charm and looks great inside.
Old 05-14-2008, 03:25 PM
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Default RE: Test stands for break in (not good)

now I will give you that, that was well said and understandable,,, thanks god I have a MVVS
Old 05-14-2008, 03:44 PM
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Default RE: Test stands for break in (not good)

Try running a BME 110 or an older 115 on a stand for a few hours without additional cooling air. You might get lucky, but the odds are against it if the rpm level is much beyond 50%.
Old 05-14-2008, 03:56 PM
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Default RE: Test stands for break in (not good)

Boy, did I open a can of worms, Lets just forget it and let them burn um up.

Milton
Old 05-14-2008, 04:39 PM
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Default RE: Test stands for break in (not good)

This is actually a good can of worms, thanks for opening it.

I just bought a new 57cc gas engine and I was about to mount it on the old test stand and get her going. It's easy to question how we could do harm. Open to the elements full prop wind over the cylinder compared to an enclosed cowled box of which most are not vented properly etc. I mean how much extra wind makes it past that spinning disk in flight anyway



Old 05-14-2008, 08:32 PM
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Default RE: Test stands for break in (not good)

Seems like to me...many of us are not wording or expaining what the heck they are trying to do or what they thought was done or went wrong! A test stand is just that...a stand made to hold a engine to test it...NOT BREAK IN. It is fine to test a engine on a test stand, and adjust it if need just a little bit. I say its helps break in to bring engine up to a temp that a run of about 2 min. Shut it down and let it cool completly. Do this a few times and you heat cycled the engine to help faster breakin. I have checked the temps of many short runs on many engines....and seen no overheating. I have a 4 cycle twin that runs within 1- 2 degress measured at the plug. Crankcases and carb intakes run about the same or even cooler than induction air. Hey the average plane and engine installation does not have to checked with all kinds of temp probes ect. Some guys on here are just to darn hi-tect with all the fancy gismos you think everyone else needs. Sure there may be a few special set-ups that need more ducts..ect....but if you read up on the plane and engine combo you are doing...you should be aware of special needs. Take it easy...run em and go fly. Capt,n
Old 05-14-2008, 08:57 PM
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Default RE: Test stands for break in (not good)

Ahh, but Captin, most won't do it your way, which is the correct way. They'll let the thing run through a tank or a gallon of gas while they go have lunch or play a video game. I've got an engine I just picked up today that has almost zero compression. Over heated on a stand was the cause. The fuel mix and tuning was as good as great instrumentation could provide, but someone forgot to turn on the blower.

As for how much air gets through the prop when it's running, here's a nice test. Go find a beekeeper or one of their supply stores. Obtain a smoker. If you're careful a road flare might do almost as well. Pump a bunch of smoke in front of the prop and watch what happens to it and how it flows. The results are enlightening.

Anything within certain bounds and limits is generally not harmful, but to excess is where the problems arise.
Old 05-14-2008, 09:25 PM
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Default RE: Test stands for break in (not good)

ORIGINAL: Pat Roy

If you're careful a road flare might do almost as well.
HE HE!! I can see the headline now!
Old 05-14-2008, 09:44 PM
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Default RE: Test stands for break in (not good)


ORIGINAL: Jake Ruddy

Either way no sense arguing.. I dont even see the need for bench run ins anyhow.. throw it on the plane add Penzoil 50:1 tune it properly from day 1 and fly it. All this other stuff is a waste of time.
A test stand sure makes it easier to tune exhaust system / prop combos compared to doing the cutting and checking on the airframe. If you are running a pitts muffler or something generic like that it is not particularly useful, but can be very useful with tuned pipes or canisters.

Mark
Old 05-14-2008, 09:46 PM
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Default RE: Test stands for break in (not good)

Hey Pat....I did have honey Bees...till one day I went near the hive and they came out stinging the _iss out of me. I got rid of them little suckers...fast. I may still have the smoker in my other garage! That sounds like a good test to do for a lot of engine fans! Best Regards Captn. ....Sick em up Josey Wells...I am taking you in!!! HA!
Old 05-14-2008, 10:06 PM
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Default RE: Test stands for break in (not good)

I once bolted a 20-10 (too small for flying, but just right for a light load and break in) on the front of a Zenoah G-62.

Hooked up the fuel line. 32:1.

Started it up and let it warm up about 2 minutes.

Full throttle.

Tuned it about 500RPM off peak.

Walked off to the shop to finish my new kit.

When the noise stopped (5g of gasoline later), I went outside and unbolted it from the stand.

Took it inside and bolted it to my plane.

Still flying it. About 40 gallons later. Runs great.

I don't break in my gas engines on a stand anymore. I think they run so good, you don't need to worry about the flame-outs and poor carbs like on a glow engine. Gas engines just RUN. Tune it up a bit and go fly it.

My point is, either way works, if you just apply a little common sense to the equation.
Old 05-14-2008, 10:31 PM
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Default RE: Test stands for break in (not good)

Monitoring the cht with a thermocouple and live data feed is also important. Temp guns are useless for even coming close to the actual cylinder temps.
Has anyone actually measured the cylinder and head temps on the test stand and in-flight with a recording instrument like the Eagle Tree Systems device? Just curious.

Bill

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