breaking in the engine
 

A guy told me at a hobby store to idle half of gallon of glow fuel to break in the engine. To me that sounds to much and that like $10!!!!

breaking in the engine
 

The guy at the store is an idiot. Don't listen to him. The purpose of breaking in an engine is to get it to OPERATING TEMPERATURE so that surfaces mate against each other.

If your engine is ABC (non-ringed) running it at idle and low temperature conditions (less than 1/2 throttle) may cause excessive wear of the cylinder taper (causing loss of compression and premature engine death).

If your engine is ringed, running it in at low temps will not harm it but will not break it in either.

Use the search function on this website and you'll find many responses on how to break in an engine. Another good bet is to open the little booklet that came with your engine and read it. It probably gives a recommended engine break in procedure.

Re: breaking in the engine
 

Sounds like the guy at the hobby shop is out to make some more money off of you.

Follow the manufactures instructions in the book that came with the engine.

Also, before you even turn over the engine remove the glow plug and add about 4 drops of after run oil or Marvel Mystery oil in the hole. Another 4 drops in the intake. Slowly turn over the engine to get it oiled replace the glow plug. Now follow the instructions in the book.

breaking in the engine
 

I hear bad advice all the time, from many sources, but bad advice from your hobby shop is unforgiveable. Idling half a gallon serves no purpose other than to waste glow fuel, and as Homebrewer said, may actually cause more harm than good.

breaking in the engine
 

Watch out for the instructions that come with the engine. I've seen ABC engines come with instructions that are for ringed engines. Doing that can kill the engine. Idleing a 1/2gal though an ABC engine is just about the worst thing you can do to it.

On the other hand, doing an ABC style break-in on a ringed engine can seize it up.

ABC engines need to get to full temp quickly. Don't run them blubbering rich.

Ringed engines need to be brought up to temp slowly, and run cooler (richer) for a while, don't lean them out from the start.

There are a lot of really good how-tos out there. If the how-to you read doesn't distinguish between ringed and ABC, find another one.

breaking in the engine
 

Here's a stupid question (okay, so the only stupid question is the one you don't ask . . . I didn't ask this soon enough):

How do you tell the difference between an ringed and ABC engine? I followed the directions that came with the engine to the letter when I broke it in. I didn't even consider the possibility that the manual might me wrong. Although I don't know why; I work in IT and every manual I read has at least one, huge error in it.

I have a OS .46 FX and the directions stated to set the needle valve to certain position, set the throttle to 25% and start the motor. Then I brought the motor up to full throttle and opened the needle valve until the engine went into "4-cycle mode" and held it for 10 seconds, then closed the valve until the engine went into "2-cycle mode" and held for 10 seconds. I repeated this until I emptied one tank.

When that was complete, I refueled and started the engine with the needle valve in the initial start position and throttle at 25%, and then set the needle value to where it "just breaks into 2-cycle operation" and ran the motor between 25% and 75%, with an occasional run up to 100% (couldn't help myself; I had to bother the neighbors a little :) ). I did that for one tank while I practiced taxing.

At the field, other than adjusting the idle valve, my instructor said the engine was fine and it started on the first crank every time. But, have I screwed my motor up?

breaking in the engine
 

This might be a totally ignorant question here, but here goes...

I'm building my first model at the moment, and I'm getting close to the point of running the engine in (I hate to use the term 'breaking in'... tempting fate there ;) ) I've never even heard one of these little two-strokes running before (O.S. 46LA) but I'm guessing that it's going to be pretty noisy. My question is, is this process going to be noisy enough and go on long enough to cause my neighbours to come out of their houses and beat me with baseball bats? If it could indeed provoke some display of domestic violence, has anyone built some kind of muffler box to run the engine in / run the engine in their basement with a cunning arrangement of plastic hosing and extractor fans venting the exhaust to the outside world?

I quite like my neighbours, and I'd hate for them to viciously kill me.

Cheers,
Neil.

breaking in the engine
 

My lawn mower is louder than the .46 I have, so treat it like you are going to run your mower for 15 minutes. If you are neighbors have a problem with that, then maybe you can run the engine at your air field (and let your neighbors mow your yard since it bothers them so much).

Actually, I'm not that big of a jerk; before I ran my engine I chatted with my neighbors and have an agreement; I'll run the motor at a decent hour, and if it should bother them, they promise to call nicely and let me know (then they will break out the baseball bats). Honestly though, it isn't any louder than a lawn mower, so it shouldn't be a big deal.

And in this month's issue of the magizine you get with your AMA membership, there's an arcticle on setting up an engine test bed inside. Looked perfect for those cold, windy, winter nights.

breaking in the engine
 

There's no reason you can't "run-in" your engine at the field. I ran 3 tanks through mine just getting the mixture and throttle linkage/servo/radio settings sorted out.

breaking in the engine
 

Honestly though, it isn't any louder than a lawn mower

True but they have a high pitch that gets on some peoples nerves.

Try and see what happens

breaking in the engine
 

Thanks for the tips, guys. I'll look out for that engine test-bed article! Sounds like a nice geeky project that I can add to my work bench :D (less 'bench' and more 'bridge of the USS Enterprise' at this point)

Cheers,
Neil.

breaking in the engine
 

Here's a thought, break in your engine while you're mowing the lawn :idea:

Admiral, the simplest way to see if your engine is ringed, is to remove the muffler, and turn the prop until you see the top of the piston. If you see the ring, it's ringed!

breaking in the engine
 

Oh come on, every time I have finished running that engine I tighten all the bolts on the head and muffler. After flying this weekend I went to tighten those bolts again and they finally didn't need to be tightened, although I will still check them after flying. I just don't want to take the muffler off and go through all of that again :)

Oh well, I'll check that when I get home tonight. It will give me a reason to head to the basement after dinner :D Using the break in method I described above, I guess that I should be hoping I have an ABC engine???? If it is ringed, am I in trouble?

breaking in the engine
 

Whats a ABC engine? O yeah the engine for the plane is a mini Hemmi. J/K

breaking in the engine
 

AdmiralHam,
If it's ringed, and still running well, it's fine.

ABC stands for Aluminum, Brass, Chrome. It means an Al piston running in a Chromed Brass liner. The liner is cut in a taper, so that the bore is smaller at the top than the bottom of the piston stroke. That's why new ABC engines have that "bump" or "grind" at the top of the stroke. That's a GOOD thing, not a mistake. As the engine heats up, the liner expands faster than the piston, and at full temp, you get the right piston-liner seal and the right compression. You want to avoid running them cold because you don't want to wear down the fit when the engine is cold, as all you will do it loose power when it hits full temperature. That's why you don't run an ABC engine at idle or overly rich for long when new. All you are usually breaking in is the con rod and wrist pin fits, you aren't adjusting the piston-liner fit, you want it tight. ABC engines also handle being run overly lean fairly well, since the overheating condition just causes the liner to over-expand so the engine looses compression and runs poorly. ABC engines produce a bit more power than ringed engines in the smaller engine sizes, but they do wear out a lot faster, a ringed engine will usually last about 3 times as long under the same conditions. As a side note, OS engines aren't actually ABC, they are ABN, they use nickle instead of chrome on the liner, and early versions of the FX line had a problem with the nickle flaking off on overly hot/lean runs, eating the engine. As far as I know, that's been fixed though.

Ringed engines (usually) use an aluminum piston and a liner that is steel. They have an iron or steel ring around the top of the piston. There is a slight gap in teh ring, so when the engine is cold, they appear to have less compression, the total opposite of an ABC engine. As the engine heats up, the ring expands and seals against the liner and closes the gap. When breaking in a ringed engine, you are seating the ring to the piston and liner, and that's best done with lots of cool oil, running slowly at a lower temp, exactly the opposite of ABC. If you overheat a ringed engine bad enough, the ring can "seize", or expand too much so that it develops too much friction with the liner and stop the engine. After this, it's usually time to replace the piston/ring/liner. Sometimes you can break a con rod this way, though it's less common. So you don't want to overheat your ringed engines. Oh, because you have the ring in there, ringed engines also handle eating a bit of dirt better than ABC engines. The ring will tend to help seal up really small gouges in the liner. ABC engines can't do this, so you have to be more careful about dirt.

As an amusing experiment, find two engines, one ABC and one ringed in about the same size. Flip them through compression a few times cold. Then start em up, and run them to get them good and warm. Stop them, and then flip though compression again. You should see that the ringed engine has MORE compression when hot, while the ABC engine has LESS than when it was cold.

These days, I think all engines in the .46 and smaller classes are ABC or ABN. If someone knows of a ringed .40, let me know, please? It used to be that you could get the same engines in ABC or ringed. At the time, the ABC ones costed more and produced a bit more power. The funny thing is that ABC is actually cheaper to make, which is a big reason that the small engines are all ABC now. I have two OS .32F engines from years ago. One is ABC, the other is ringed. I can't tell them apart with out taking off the muffler :) So, in the end, it really isn't a huge deal either way.

As long as you don't routinely overheat your engine, or do an extremely long and cold breakin, or overly fast non-breakin, you really won't hurt most engines either way. You may not produce absolute max power from it, but generally, most guys don't care if they loose 2k rpm because they broke it in overly fast. (I have 3 Mag .28 ABC engines. Last weekend, one tached at only 16.5k, the other was over 18k. But I fly combat, so I noticed that power drop. Flying sport, most guys wouldn't notice or care, and wouldn't be pushing 18k anyway. But it looks like time for a new piston/liner in one of my engines).

(for all that blather, I don't consider myself an engine expert. I don't rework them (other than parts replacements))

breaking in the engine
 

Get a used Mo Ped. Muffler at a motor cycle shop, A peace of hose and clamp it to plane muffler . That will kill noise you would not believe how quiet the can be, Works on gas and glo engines!

breaking in the engine
 

Well i just break in my engine and if my neihbors have a problem they can come over lol. But because im a kid i don't know if they would be more or meanies (dont want to cuss) or be more cool about it. Wait what if i do it in my garage with grage door closed and put towels all the way on the edge of the door. J/K!!!! that would kinda kill me. But thanks guys. should be getting my plane next week :)

breaking in the engine
 

I just read a thread a couple days ago where someone was complaining about that very problem with an FX engine, so it looks like they haven't fixed it yet.

breaking in the engine
 

I know this is going to sound totally ignorant, but what is the difference between an engine "2-stroking" and 4-stroking"? I know the difference between a 2 stroke and 4 stroke engine, but not sure what OS is referring to in there instructions.

Thanks

breaking in the engine
 

You can tell by the sound of the engine running whether it is "2-stroking" or "4-stroking". Running it very rich will cause it to 4-stroke, meaning that it only fires once every other compression stroke.

breaking in the engine
 

Thanks,

I thought it was something along those lines but was unsure. Will be breaking in my engine this weekend if the weather is nice. :)

breaking in the engine
 

I've heard, but am not sure about this, that when a 2-stroke is "4-strokeing" it isn't actually fireing every other revolution, it just sounds like that, it's really an acoustical trick caused by the prop, exhaust frequency, your typical muffler, the raw (liquid) fuel in the exhaust, the cooler exhaust temps, and the human ear's responses to different frequencies. Don't take my word for it though. I read that somewhere, but I forget my source, so I can't go verify that info.

Anyway, as TailDragging said, it means run rich enough that the engine sounds like it's hitting every other stroke, it's pretty obvious, once you hear it, you'll know it.

breaking in the engine
 

My neighbor has a real annoying barking dog, so I run in my engines to do my best to pay him back! No, we don't talk much.

breaking in the engine
 

I always used to think that the 4 stroking sound was simply because the very rich mixture slowed down the flamefront to the point it was still burning when the exhaust port opened. So instead of getting a "bang" out the port each time you got a "wumpf" instead. It turns out I was wrong and they do actually regularly skip one power stroke.

If you go to the web page I do for my club at http://www.holdfastmac.com.au/tech.html and click on the top link for the Super Tigre 46 you'll get to a graph (the first graph) which shows the actual torque developed at all points over a couple of revs while 4 stroking.

The reason WHY it skips a beat still isn't known for sure but the best guess is that the rich power stroke contaminates the next charge to the point it's unable to fire but when it clears out the exhaust then the next charge is combustible.

But that's not the end of the mystery about how these apparently simple engines operate. You'd expect that if it's only firing every second rev then it'd have half the HP or a bit less. But in fact they develop about 75% the HP as it would firing every stroke. This is usually put down to be because the incoming charge that WILL fire is less contaminated than a normal 2 stroking charge so more power can be extracted from it.

breaking in the engine
 

Wow, that's come really cool data. Very interesting.