Notices
Glow Engines Discuss RC glow engines

New ABC...sloppy rich running

Old 04-14-2005, 02:31 AM
  #1  
Thread Starter
 
downunder's Avatar
 
Join Date: Oct 2002
Location: Adelaide, AUSTRALIA
Posts: 4,527
Likes: 0
Received 1 Like on 1 Post
Default New ABC...sloppy rich running

I've retitled the thread because it seems too many focussed on the words "break in" and therefore missed the point. If there's anyone alive today who hasn't seen the original thread it's at
http://www.rcuniverse.com/forum/m_28..._1/key_/tm.htm . The main reason I've started this thread is to condense the 5 (so far!) pages of the original (BTW, I loved the part about "it's hard to hit a moving target" ).

But to sum up, we've all heard that if a new, unrun ABC is run too rich from the getgo or even during the break in period for any length of time at all then there's a likelihood that this rich (as in 4 stroking rich) running could cause immediate and permanent damage. This damage can be anything from excessive wear on the piston through to breaking rods because of "compression-tension" cycling of the loads. However, I'd never seen anything by any manufacturer specifically warning against running in a 4 stroke, they all seem to say run it rich but there's never a proper definition of "rich". The closest I've seen was a point barely above the break from a 4 stroke into a 2 stroke mode. Now this is fine if you've run engines before and know what the 4 stroke sound is like but what does a newbie do? All he knows is that the engine is running and makes a noise. Now very few newbies will go out and buy a Jett, Nelson or Profi as their first engine so all this talk about damage is directed against sport type engines.

OK, so that's what we've all heard but I've had to wonder if there's any truth behind it or is it all just hearsay? Years ago I decided that if I ever got a new ABC (cheap ) I'd consider it expendable and put my money where my mouth is and see what happens by running it extremely rich right from the start. And not for just a short time, I wanted to really wring it's neck over an extended period to give it every chance to show damage. It had nothing to do with trying to run it in, simply to find out if it would be damaged. From what I'd learned playing with model engines for over 45 years plus over 21 years as an aircraft engine fitter (including 3 years as an apprentice doing nothing but theory and practical training) I was fairly confident it'd survive ok but I wanted to know for my own satisfaction. If I was wrong then I'd have learned something.

Preamble (rambling?) over, down to business. I picked up a brand new Bluebird 51 for $40 (about US$30) from "you-know-where" so here was my chance. I only had one shot at doing this experiment so I had to eliminate as many variables as possible. I chose to use a 9x6 wood prop to keep the loads down because I was more interested in piston wear than rod wear. I chose to use a fuel with 24% oil (1/3rd being castor) and zero nitro for two reasons. The first was that I wanted the engine to run as cool as possible and didn't want a low oil content contributing to excessive wear, the second reason was I already had it mixed

The first tank was done in 3 runs of 2 minutes each in a solid 4 stroke at 11.7K with a head temp of 175F. The second tank was slightly richer at 10.3K and 160F and the third tank at 8.7K and 145F (when I could hold the head for maybe 5 seconds before it became uncomfortable). By now it had a total of 18 minutes. To check for any wear I'd twice taken off the muffler and looked at the piston through a magnifying glass and couldn't see any signs at all. It still looked brand new. The pinch still seemed to start at the same place but at this point I had an idea about how to check it a little more scientifically. I took out the plug and mounted a degree wheel in front of the prop. This allowed a very fine feel for the start of the pinch and was occurring at 45 degrees BTDC. For rod wear I put the piston into the pinch to lock it in place then checked the freedom of movement at the prop tip. This was about 1/16" and never varied.

I continued running it very rich until it had done 45 minutes at which time I figured that surely there'd be signs of damage if it was ever going to have any so I stripped it down for a close look (and here I'm going to cheat and do a cut and paste from the first thread) but note that where I use the word "wear" I'm not talking about damage, I'm talking about things you'd expect to see in an engine that's been run.

On the piston, the only evidence of any wear was the beginnings of the ring you usually see close to the crown. Most of this was on the transfer side of the piston with only a hint of it beginning on the exhaust side. The photo shows the transfer side. There was no detectable play in the wristpin bosses in the piston.

The liner was starting to show signs of smoothing out because the cross hatching was getting faint. One area between the front transfer and the boost port had taken on a very high polish like a mirror.

Now for the rod (and I know it's not one of the squeaky tight high performance engines). It's difficult to show in the photos because of reflections etc but the upper surface of the rod bush is taking on a nicely polished finish while the bottom half still has the original machining marks. This tells me there was definitely none of this "piston jamming in the pinch and the rod dragging it down" going on. In other words, no "compression-tension cycling" of the rod. One myth busted at least and it came as no surprise to me.

(End of cut and paste ).

One thing I'll add here which I didn't think important at the time was that with the head off I turned the piston just into the pinch and measured the point it began to pinch with a depth gauge. This was .075" BTDC and was the equivalent of about 30 degrees BTDC (I also used a shorter backplate screw to stop the liner from lifting).

My conclusion from what I saw in this engine? Absolutely nothing abnormal. My opinion is that it was barely showing signs of even running in. Once again though, I'm not advocating this as a way to run them in, simply that in this test with this engine (which seems to be a typical off the shelf ABC sport engine) running slobbering 4 stroke rich caused no harm at all.

The next post will be the results of running it in as close as possible to the "do it my way" thread
Attached Thumbnails Click image for larger version

Name:	Jh17137.jpg
Views:	52
Size:	38.2 KB
ID:	258026   Click image for larger version

Name:	Cy77568.jpg
Views:	55
Size:	36.0 KB
ID:	258027   Click image for larger version

Name:	Bg94184.jpg
Views:	44
Size:	22.1 KB
ID:	258028   Click image for larger version

Name:	Un34359.jpg
Views:	48
Size:	33.6 KB
ID:	258029  
Old 04-14-2005, 03:34 AM
  #2  
Senior Member
 
DarZeelon's Avatar
 
Join Date: Apr 2003
Location: Rosh-HaAyin, ISRAEL
Posts: 8,913
Likes: 0
Received 2 Likes on 2 Posts
Default RE: New ABC...sloppy rich running

Brian,


This is from the manual for Super Tigre engines:
-----------------------

The ABC engine break-in process is similar to the ringed engine break-in
process with one major difference:ABC engines are not run as rich
as ringed engines in the early process.
Choke and start your SuperTigre ABC engine in the same manner as
detailed above in the Initial Running and Break-in (Ringed Engine).
Let it warm up for 30 seconds,and then advance the throttle to full. Now
slowly lean the high-speed needle while you listen to the engine. As you
lean the needle, you will hear the engine increase in RPM. At some
point, you will hear the engine sound like it’s jumping up and down in
RPM.The exhaust sound will be jumping up and down in pitch. You want
to continue to lean the engine until it’s running mostly at the higher-pitch
sound, with just an occasional break to the lower sound. Let the engine
run at this setting for five minutes.

------------------------------------

If the ABC engine will sustain no (?) damage from being broken-in as rich as a ringed piston engine, why do you suppose Super-Tigre tells the user to do the break-in less rich; just lean of the point where it breaks into a two-cycle (with occasional four-cycle 'burping')?


Since you are out to fail the method I described in my thread; to bust "myths", are you sure you can be completely objective as to the final results?

Do you think your testing on two examples of one cheap engine, from 'you know where' will produce results that can be trusted?

This goes for both negative and positive results, of-course.
Old 04-14-2005, 04:09 AM
  #3  
Banned
 
Join Date: Mar 2003
Location: Tokoroa, , NEW ZEALAND
Posts: 3,848
Likes: 0
Received 0 Likes on 0 Posts
Default RE: New ABC...sloppy rich running

I don't think anyone is going to win this debate by being totally one-sided or by allowing ideology to over-ride reality.

Downunder's results would indicate that when run with *more* oil than most people would use (ie: I have never run a modern engine with 24% oil, not even during break-in) and *if* that engine is not too tight to start with, then an ABC can be run new out of the box in an excessively rich condition without inflicting damage that is visible within the first hour or so of operation.

However, DarZeelon may be correct in his assertions also - because we don't know what would happen if "off the shelf" fuel, with a high synthetic content had been used, what might happen after more running, or how a "tighter" pinch may have affected results.

For example -- fatigue in aluminum (conrods) is something that can occur insideously. The rod might look just fine one moment and then fail completely the next -- without any ovalling of the journals (especially if they're bushed properly).

Downunder has shown that *his* engine, run with *his* fuel and with a quite light load appears at this stage in its life to have suffered no damage.

It would be risky however, to consider this to be any kind of proof that it's okay to run all ABC engines slobbering rich for extended periods.

So I figure why take the risk?

I'll continue to run my ABCs in by simply using an inch less pitch (or diameter) on the prop, tuning them just shy of 4-stroking, putting a tank through them on the ground and then flying the living snot out of them.

Using this technique, my ABC engines seem to keep getting better for at least the first 10 hours of operation and then remain good and strong for as long as I care to keep flying them.

Chances are that a "rich" run or two won't significantly hurt them -- but if mine begin 4-stroking for any reason while I'm flying then I land and lean them out a bit.

Both DarZeelon and Downunder are right, it's just that each is also a little bit overstating their case perhaps and the real truth may be closer to what I've tried to get across in this posting.
Old 04-14-2005, 05:07 AM
  #4  
Thread Starter
 
downunder's Avatar
 
Join Date: Oct 2002
Location: Adelaide, AUSTRALIA
Posts: 4,527
Likes: 0
Received 1 Like on 1 Post
Default RE: New ABC...sloppy rich running

With the engine reassembled I did what I should have done in the first place and went to the field to use their test stand so it could all be done at once

I used the same fuel for the same reasons but fitted a 10x6 APC prop because that's closer to what the average modeller would use. The first run was for 2 minutes at 13K with a head temp of 300F which worried me but I was going by the book and it gave the occasional misfire into a 4 stroke (only for an instant). Subsequent runs I chickened out and richened it very slightly so that for the next 18 minutes it ran at 12.7K at 290F.

When it reached 20 minutes total part way through the 4th tank I was at the point (or just past) where the book says they're run in so I began slowly leaning it out. It peaked and held nicely for the recommended one minute at about 14K which I thought was OK for zero nitro and a lot of oil. I might add (because I just gotta say it ) that the needle valve was quite insensitive and gave me a fine control over the mixture (another Myth busted??).

So bring it home and strip it down once again.

First, remove muffler and look at the piston. There was just a hint of the matte finished "ring" at the top. Fair enough, that might get more pronounced with more running.

Turn the engine over with the plug still in and I could feel a pinch so take the plug out and put on the degree wheel. The pinch started at 42 degrees which was virtually the same as it had always been. No problems.

Take off the backplate and it was like brand new, no hint that the rod had touched it and started to give the swirling marks you usually see (the swirls are quite normal BTW).

Take off the head and there was a trace of discolouring beginning on the squish band (I've included a photo of the head because I like the shape and the large tapered squish band) and also on the piston crown.

Time to use the depth gauge on the pinch....hmmmm...I'll come back to that!

Remove the liner and the cross hatching is somewhat fainter, in fact it's almost disappeared from the transfer (thrust) side. It looks fine though.

The piston looked fine on the exhaust side with that barely discernible matte ring as I mentioned before but it didn't extend all the way around. On the transfer (thrust) side there was a very bright polished line about 1/8" down from the crown which varied in width erratically. I'm not too keen on that.

The big end bush in the rod now showed evidence of polishing on the lower (supposedly non load carrying) surface. I didn't expect to see that.

The next thing I wanted to check was the pinch with the loose piston and liner so I reoiled both with straight castor and pushed the piston up with my finger. It nipped at .130" before TDC. The actual measurement was .310" but deck height is .180". This sounds to be very good but brings me to the part where I said earlier I'd come back to it.

Recall (or re-read if you must ) that I went to use the depth gauge to check the nip while the piston and liner were still in the engine. With the head off there wasn't any nip! The piston turned over TDC as smooth as silk. That was something I most definitely didn't expect. This did not happen after that first 45 minutes of rich running. That time there was a definite pinch with the head removed. Now I could only feel a pinch using my finger but assembled there's quite considerable leverage from the prop and the very small rod angle so close to TDC. Even by turning the crankshaft the rod leverage overcame any feel I might have had.

I then reassembled the engine minus head and still there was no pinch so I fitted the head and the pinch returned! Obviously something strange was happening so I loosened the head screws. No pinch. I began retightening in the normal cross pattern a bit at a time (as I'd done before) but this time I turned the piston over TDC as I added a bit of tension to each screw. If a screw caused any pinch I'd loosen it and try another. My assumption here was that any pinch must be caused by some distortion of the liner (considering we're working with virtually zero clearances) but eventually I found a sequence that allowed the head to be fully tightened and yet no pinch.

Why did this happen? I can only guess that because the head isn't made from the same alloy as the piston it then expands and contracts more from hot to cold. The liner has no option but to follow the head because of the clamping pressure between the head and crankcase. I'd be interested to know if anyone else has noticed this.

Now my conclusions from running in as perthe book. From the 20 minutes I saw far more wear than the 45 minutes prior with very rich running. This wear includes the bright ring on the thrust side of the piston, the polishing on the lower side of the rod bush and that strange loss of pinch. What affect these might have on the life of the engine or power is impossible to say, it may have no affect at all and could even have happened if I'd continued running it rich for another 10 hours or more.

As far as I'm concerned if I was to run in another ABC I wouldn't go any leaner than the break from a 4 stroke and for considerably longer than 15 or 20 minutes. I'd put up with 20 minutes bench running but keep the same tune for flying until it had maybe an hour or more before slowly leaning it out. This is only what I'd do and that's all I wanted to find out from my little experiment.
Attached Thumbnails Click image for larger version

Name:	Pn37426.jpg
Views:	52
Size:	27.3 KB
ID:	258034   Click image for larger version

Name:	Zu64997.jpg
Views:	42
Size:	32.8 KB
ID:	258035   Click image for larger version

Name:	Uz68813.jpg
Views:	52
Size:	19.6 KB
ID:	258036  
Old 04-14-2005, 05:47 AM
  #5  
Banned
 
Join Date: Mar 2003
Location: Tokoroa, , NEW ZEALAND
Posts: 3,848
Likes: 0
Received 0 Likes on 0 Posts
Default RE: New ABC...sloppy rich running

Could it be that the combination of very high levels of oil (24% *is* high) and slobberingly rich running (meaning that a *lot* of oil was present) in the first runs caused very little wear -- but also did very little to run the engine in.

Maybe the leaner runs produced the wear patterns you've noticed as a normal part of the running-in process.

Remember that running in involves the wearing of parts so that they achieve satisfactory operating clearances so to do this *some* wear must occur.

Maybe people will be a little less worried about the effects of a rich-run with their ABC -- that's fine (if they're using 24% oil with a fairly high castor content) -- otherwise we can't tell.
Old 04-14-2005, 06:29 AM
  #6  
My Feedback: (12)
 
piper_chuck's Avatar
 
Join Date: Jun 2004
Location: Columbia, SC
Posts: 8,044
Likes: 0
Received 0 Likes on 0 Posts
Default RE: New ABC...sloppy rich running

ORIGINAL: downunder
The main reason I've started this thread is to condense the 5 (so far!) pages of the original (BTW, I loved the part about "it's hard to hit a moving target" ).
I'm glad I was able to provide a bit of humor.
But to sum up, we've all heard that if a new, unrun ABC is run too rich from the getgo or even during the break in period for any length of time at all then there's a likelihood that this rich (as in 4 stroking rich) running could cause immediate and permanent damage. This damage can be anything from excessive wear on the piston through to breaking rods because of "compression-tension" cycling of the loads. However, I'd never seen anything by any manufacturer specifically warning against running in a 4 stroke, they all seem to say run it rich but there's never a proper definition of "rich". The closest I've seen was a point barely above the break from a 4 stroke into a 2 stroke mode. Now this is fine if you've run engines before and know what the 4 stroke sound is like but what does a newbie do? All he knows is that the engine is running and makes a noise. Now very few newbies will go out and buy a Jett, Nelson or Profi as their first engine so all this talk about damage is directed against sport type engines.
For reference, here's what K&B says about running an ABC engine too rich:
ABC engines are designed to run at operating temperatures, NOT COOLER temperatures. RUNNING THE ENGINE TOO RICH WILL RUIN THE FIT. If the operating temperature is not reached, the piston is prematurely worn from lack of clearance. You do not want to "break-in" an ABC engine at a very rich setting. Just a slightly rich setting for the first 30 to 45 minutes of running is adequate.

And about break-in and running:

A model engine makes sounds that will tell you how it's performing. You'll have to listen very carefully for them, recognize their message, and make adjustments to the fuel control needle valves accordingly. The mixture of fuel and air is controlled by the amount of fuel metered by the needle valve.

SLOPPY RICH MIXTURE running is characterized by a very slow, irregular, sputtering exhaust sound. The exhaust gas will be very smoky and contain many droplets of oil. NEVER RUN AN ABC ENGINE AT THIS SETTING. The cylinder is not able to heat properly and the fit will be ruined in a short time.

RICH MIXTURE running is characterized by a slower, sometimes irregular, sputtering exhaust sound. The exhaust gas will be smoky and probably contain small droplets of oil. NEVER RUN AN ABC ENGINE AT THIS SETTING. The cylinder is not able to heat properly and the fit will be ruined in a short time.

FOUR CYCLING or SLIGHTLY RICH running is a rich type setting, but it is fast enough to pull the airplane. This is the setting you normally look for before launching the airplane because the engine will run leaner when airborne.

PEAKED OR TWO CYCLE. As the main needle is closed (clockwise), it reduces the amount of fuel mixed with the air drawn into the engine. At a specific point, which varies with each engine, air temperature, altitude and relative humidity, the exhaust note will change quickly into a smooth, powerful note. If the needle is closed further, the note will stay smooth, but will weaken. The peak occurs just at the break point from a rich setting and further leaning will ruin the engine. A lean setting raises the engine heat above the safe point, reduces lubrication, and destroys glow plugs due to high combustion temperature. This is very harmful to the engine and your investment. Learn to tune the engine before flying. Remember, a little rich is always preferred for long motor life.



AIRBORNE BREAK-IN

1> BREAK-IN running should be done with the recommended propeller at a slightly rich setting. You want the engine to be at running operating temperatures. The needle valve should be set at a point just into this range from a four cycle setting. Fly the plane at maximum throttle for 2 minutes, then throttle back to half throttle for approximately 30 seconds. Repeat this sequence until approximately 20 minutes of accumulated running time has been obtained. Additionally, certain maneuvers, such as "CUBAN EIGHT'S", that allow the engine to load and unload are recommended. AVOID PROLONGED CLIMBING MANEUVERS AT MAXIMUM THROTTLE.

2> After the first 20 minutes change to normal size prop and fly an additional 15 minutes. Continue to run the engine at a slightly rich setting and fly your normal pattern.

3> After the above break-in period, run the engine at a normal peak needle valve setting. This should be a little on the rich side because engines run leaner in the air. 5% - 15% nitro may be used.

BENCH BREAK-IN

NOTE THAT THE ENGINE MUST BE FIRMLY MOUNTED ON A SOLID TEST STAND. DO NOT CLAMP ENGINE IN A VISE. Muffler may be used during bench break-in.

The initial bench break-in period is also approximately 15 minutes (15 minutes bench and 15 minutes airborne). During this time, use the recommended break-in propeller and run the engine at a slightly rich setting. It is best to run the engine for a full 10 minutes, then allow it to cool. Heating and cooling is not beneficial to an ABC engine as you what it to run at operating temperatures, not cooler temps.

1> Start the engine and run it at a rich full throttle for about 2 minutes, then let it fast idle (about 3500 rpm's) for 30 seconds. Repeat this sequence for about 10 minutes of running time.

2> Increase the full open throttle time to about 3 minutes followed by a 30 second idling period. Do this for an additional for 20 minutes.

3> Install the engine in your aircraft using an normal size prop.

The manuals for several other ABC engines I own also warn that running the engines too rich will cause damage, premature wear, etc. These engines include Webra and a Tower .75.

I'm in complete agreement with XJet, there are plenty of warnings against running ABC engines too rich, so "why take the risk?"
Old 04-14-2005, 07:25 AM
  #7  
Senior Member
 
Join Date: Jan 2002
Location: Arcen, , NETHERLANDS
Posts: 6,571
Likes: 0
Received 2 Likes on 2 Posts
Default RE: New ABC...sloppy rich running

OK folks, Lets hear what MVVS says about running in <their> engines. (they used to be squeecky tight when new)

Start the engine at half throttle, and run it four stroking rich. Every now and then, move up the throttle setting. If the engine sags, then go back to the half throttle rich setting running. The engine is run in enough for flight when it does not sag any more.

What does this tell us.
An ABC or ABN or whatever combination except steel and meehanite, will behave differently than what we old farths were used to.
Each manufacturer has his own material specifications which determine the amount of temperature rise for a given dimensional change.
In MVVS I found that a slight warming up resulted in loosing the very tight squeeking fit, which returned when the engine had cooled down almost to room temperature. This shows a very small temperature coefficient for the piston material. These engines will not be hurt by a slobbering rich running in. I even found, than when up in the air, and chasing hell, the engine could overheat and loose power, untul allowed to cool again by running at rich half throttle. Since no metal contact was present during these hot runs, no wear was evident after inspection. When run in well, this phenomenon disappeared.
It also seemed that the piston showed some "growth" during the first runs, and relieving the lower liner half by honing instantly restored full power on engines that showed longer times than the usual short sagging period during running in.
Other manufacturers probably use a different alloy, which will not allow this kind of running in, so I would be very carefull to not follow the manufacturers recommendations, be it slobbering rich, or just lean of that.
Know your engines, and believe what you see and experience. There is no magic involved. Just plain physics. Including the fact that a piston can expand the cylinder to a large extent when it rides on an oil film. Pinch start should be tested with the piston bone dry!
I also experienced the fit change by carelessly tightening the head screws. I now take my time to do it right.
Old 04-14-2005, 08:35 AM
  #8  
Senior Member
 
Join Date: Jul 2003
Location: no city, AL
Posts: 2,613
Likes: 0
Received 0 Likes on 0 Posts
Default RE: New ABC...sloppy rich running

Who would haver dreamed Downunder's experiment would generate so many responses. If I didn't know better I'd think some toes had been stepped upon, or perhaps a sacred cow had been gored

jess
Old 04-14-2005, 09:24 AM
  #9  
Thread Starter
 
downunder's Avatar
 
Join Date: Oct 2002
Location: Adelaide, AUSTRALIA
Posts: 4,527
Likes: 0
Received 1 Like on 1 Post
Default RE: New ABC...sloppy rich running

ORIGINAL: jessiej
Who would haver dreamed Downunder's experiment would generate so many responses.
Yeah...I'm glad I didn't start a post on my variable compression glow head. Imagine what would have happened then? Why mess around with what the manufacturers give you? Don't they know best? Ah well, I'll just use that one quietly every time I fly

Pe, that's interesting about the MVVS, I hadn't heard that one before. I wonder what the "other" MVVS dealer will say
Old 04-14-2005, 09:26 AM
  #10  
Senior Member
 
Join Date: Jan 2002
Location: Arcen, , NETHERLANDS
Posts: 6,571
Likes: 0
Received 2 Likes on 2 Posts
Default RE: New ABC...sloppy rich running

Hey Jess, You should know better than to gore a sacred cow. Bad JuJu.

Yes Downunder showed that not all tales hold up very well when scrutinized. There are of course a few factors which bias his engine towards his conclusions, but that is nitpickin' (or should it be: "his conclusions to his engine" ??)
Let the use of that grey mass we have prevail.

Great job Downunder!
Old 04-14-2005, 09:48 AM
  #11  
Senior Member
 
DarZeelon's Avatar
 
Join Date: Apr 2003
Location: Rosh-HaAyin, ISRAEL
Posts: 8,913
Likes: 0
Received 2 Likes on 2 Posts
Default RE: New ABC...sloppy rich running

ORIGINAL: piper_chuck

..................

SLOPPY RICH MIXTURE running is characterized by a very slow, irregular, sputtering exhaust sound. The exhaust gas will be very smoky and contain many droplets of oil. NEVER RUN AN ABC ENGINE AT THIS SETTING. The cylinder is not able to heat properly and the fit will be ruined in a short time.

RICH MIXTURE running is characterized by a slower, sometimes irregular, sputtering exhaust sound. The exhaust gas will be smoky and probably contain small droplets of oil. NEVER RUN AN ABC ENGINE AT THIS SETTING. The cylinder is not able to heat properly and the fit will be ruined in a short time.

FOUR CYCLING or SLIGHTLY RICH running is a rich type setting, but it is fast enough to pull the airplane. This is the setting you normally look for before launching the airplane because the engine will run leaner when airborne.

PEAKED OR TWO CYCLE. As the main needle is closed (clockwise), it reduces the amount of fuel mixed with the air drawn into the engine. At a specific point, which varies with each engine, air temperature, altitude and relative humidity, the exhaust note will change quickly into a smooth, powerful note. If the needle is closed further, the note will stay smooth, but will weaken. The peak occurs just at the break point from a rich setting and further leaning will ruin the engine. A lean setting raises the engine heat above the safe point, reduces lubrication, and destroys glow plugs due to high combustion temperature. This is very harmful to the engine and your investment. Learn to tune the engine before flying. Remember, a little rich is always preferred for long motor life.

Chuck,


If I understand this correctly, the settings above are in order of richness; from the richest mixture to the leanest (not including a damaging lean-run...).

If so, what is described here as 'FOUR CYCLING or SLIGHTLY RICH', is not what I mean when I talk about four-cycling, in which the engine actually fires on alternate revolutions.

This will actually happen when the mixture is 'RICH', or even on when 'SLOPPY RICH'.


Maybe the different understanding of this term is what prompted Profi to use it in their break-in instructions?


My definition of 'SLIGHTLY RICH' means the engine is clearly firing on nearly every revolution, yet is not peaked and it does emit a smoky exhaust, with some unburnt fuel and oil droplets.

But calling such a setting 'FOUR CYCLING' is a bit misleading, or rather completely misleading.

I believe you will agree on this issue.
Old 04-14-2005, 10:06 AM
  #12  
Senior Member
 
DarZeelon's Avatar
 
Join Date: Apr 2003
Location: Rosh-HaAyin, ISRAEL
Posts: 8,913
Likes: 0
Received 2 Likes on 2 Posts
Default RE: New ABC...sloppy rich running

Brian, Pé,


Copied word for word, directly from the instruction included with an MVVS .49:

-------------------------

RUNNING IN

The engine should be run-in out of the model. The flight air-screw and the FAI fuel i.e. 80% Methylalcohol and 20% Castor oil are used for running in of an engine with glow plug. The self ignition engines are run with 45% Ether, 30% Kerosene and 25 Castor oil. A fuel should be fitted into the fuel tube.

The engine is set for medium revolutions with a richer fuel mix. After 15 min. of running tune the engine for top speed. If it will run for one minute without speed drop, then the running-in period is finished. If the revolutions drops, the procedure must be repeated...
----------------------------------

Pé, please open the instruction and you will see it as I did.

It does not say 'four-cycling', or anything else....


So I adopted the procedure most appropriate for this type of engine.
It is what I described in my thread.

This is what one of the other MVVS dealers says, Brian.
Old 04-14-2005, 10:25 AM
  #13  
Senior Member
 
Join Date: Jan 2002
Location: Arcen, , NETHERLANDS
Posts: 6,571
Likes: 0
Received 2 Likes on 2 Posts
Default RE: New ABC...sloppy rich running

Dar, What is your point?

Can you set the engine at a rich medium rpm setting without four stroking? (and go by the book)
I can't, unless I use 25% nitro.
Example. a 3,5cc engine determined to run at 16,000 static, set for 8000 - 9000 rpm running in on a MA 8x6 prop. It is four stroking when at a rich mixture. When not, it is way too lean. I need about two 50 cc tanks to get the engine to best rpm. After that, I fly (MA 9x4 prop), and try to rev up the engine as high as possible, diving the plane etc.
This procedure gave me excellent results for competition engines, so I do think the manual meant just that.

Other ABC engines I run in full bore, just rich off peak, which seems best. Not MVVS though. They use a different metallurgy; I still have to ask just what.
Old 04-14-2005, 10:55 AM
  #14  
Senior Member
 
DarZeelon's Avatar
 
Join Date: Apr 2003
Location: Rosh-HaAyin, ISRAEL
Posts: 8,913
Likes: 0
Received 2 Likes on 2 Posts
Default RE: New ABC...sloppy rich running

Pé,


I asked Mr. *vajda about that, in a phone conversation.

He first said just run it as you would any ABC engine. The metallurgy is the same as any other ABC engine; a high silicon aluminium piston and a chromium plated brass sleeve.
He even said to just run the engine and fly it.

Medium revolutions does not mean half the RPM of maximum revolution.
So the best treatment, from my experience so far, the engine at 75-80% of its maximum flight prop HP is the most appropriate way to get the results.

That would mean 90-93% of the RPM on the flight prop, or the maximum flight prop RPM, on a 1" smaller prop.

At half the RPM any engine makes only 1/8 of its intended usable HP.
This setting cannot even get the engine warmed up enough to break it in.


My ABC customers are all still using their original piston and sleeve.
Some have already accumulated as much as 70-80 hours on it.

So my technique cannot be too flawed, can it?
Old 04-14-2005, 11:16 AM
  #15  
My Feedback: (12)
 
piper_chuck's Avatar
 
Join Date: Jun 2004
Location: Columbia, SC
Posts: 8,044
Likes: 0
Received 0 Likes on 0 Posts
Default RE: New ABC...sloppy rich running

ORIGINAL: DarZeelon
If I understand this correctly, the settings above are in order of richness; from the richest mixture to the leanest (not including a damaging lean-run...).

If so, what is described here as 'FOUR CYCLING or SLIGHTLY RICH', is not what I mean when I talk about four-cycling, in which the engine actually fires on alternate revolutions.

This will actually happen when the mixture is 'RICH', or even on when 'SLOPPY RICH'.
I agree that K&B's description of the term four cycling appears to be different that other (most?) people's use of the word. However, I don't see it as very relevant, because the instructions don't use the term four cycling, they use the term slightly rich. When you read the description of slightly rich, without fixating on the term four cycling, it's pretty clear that they meant the backed off from peak setting, that sport fliers (the ones who want their engines to last) use.

Most sport fliers I know don't set their engines for absolute peak, this is an area of performance that's usually only needed for people who race, or feel the need for speed, and are willing to pay the price of buying replacement parts or engines. They also don't try to fly at a setting that you would call four cycling. They usually fly at a slightly rich setting.
Old 04-14-2005, 12:46 PM
  #16  
Senior Member
 
Join Date: Jan 2002
Location: Arcen, , NETHERLANDS
Posts: 6,571
Likes: 0
Received 2 Likes on 2 Posts
Default RE: New ABC...sloppy rich running

ORIGINAL: DarZeelon

Pé,


Large snip

My ABC customers are all still using their original piston and sleeve.
Some have already accumulated as much as 70-80 hours on it.

So my technique cannot be too flawed, can it?
Dar, The question in this thread is not about flawed techniques, but about running in rich, even very rich.
Your technique works, and so does mine. You run in the first two tanks at higher power levels, whilst I dont. I just get the engine running with plenty of oil to wash away any first wear particles before I turn the heat on. This is what works for me. After this type run in I even ran engines as low as 10% oil without damage. (I prefer 20% oil though).
So this gives Downunder some foothold doesnt it?
I believe it is not rocket science, and I never wrecked an ABC engine in it's first runs. Only one, but that was a diesel, and I was 13 years old when that happened, and it wasn't ABC either.
Old 04-14-2005, 03:47 PM
  #17  
My Feedback: (16)
 
w8ye's Avatar
 
Join Date: Dec 2001
Location: Shelby, OH
Posts: 37,576
Received 9 Likes on 9 Posts
Default RE: New ABC...sloppy rich running

Those few of us that are so vehemently idealistic must realize that we do not have actual control over what JOE BLO does with his new engine.

We can only suggest....

The rest is up to the owner...

Enjoy,

Jim
Old 04-14-2005, 04:12 PM
  #18  
Senior Member
My Feedback: (9)
 
Join Date: Dec 2001
Location: Breckenridge, TX
Posts: 123
Likes: 0
Received 0 Likes on 0 Posts
Default RE: New ABC...sloppy rich running

Well,
I just got in a new OS 46 AX and I intend to break it in sloppy rich on Cool Power.
If it breaks,I'll just get another one.
Mike
Old 04-14-2005, 04:18 PM
  #19  
My Feedback: (12)
 
piper_chuck's Avatar
 
Join Date: Jun 2004
Location: Columbia, SC
Posts: 8,044
Likes: 0
Received 0 Likes on 0 Posts
Default RE: New ABC...sloppy rich running

ORIGINAL: w8ye
We can only suggest....
The sad part is that even with all the collective "wisdom" that's focused on these threads, there is not a unified suggestion. No wonder beginners get confused.
Old 04-14-2005, 06:13 PM
  #20  
Senior Member
 
Join Date: Jul 2003
Location: no city, AL
Posts: 2,613
Likes: 0
Received 0 Likes on 0 Posts
Default RE: New ABC...sloppy rich running

[No wonder beginners get confused.]

And sometimes experts.

jess

Old 04-14-2005, 08:46 PM
  #21  
My Feedback: (21)
 
Flyboy Dave's Avatar
 
Join Date: Mar 2002
Location: Pinon Hills, CA
Posts: 13,847
Received 5 Likes on 5 Posts
Default RE: New ABC...sloppy rich running

Gentlemen, we need to standardize our terminology about richness.
Some keep quoting K&B's description of sloppy rich running. I think
they are off the charts, and not in line with a "real world" examples.

Let me offer my version, in a scale that I have devised. I think it is
pretty accurate in the general sense of two cycle engine operation,
to include the small aero-model engines.
__________________________________________________ ______

From lean to rich:

0. Engine not getting enough fuel to run.
1. Engine ran but was set too lean. Overheating and seizure resulted in
engine damage (repairs are needed before engine will operate again)
2. Engine is running, but is slightly lean with some over heating.
3. Engine is running properly, but should be richened for sustained
high speed operation.
4. Engine is slightly rich, will sustain high speed operation.
5. Engine is set rich, and will sustain high speed operation, as well as
extreme load operation.
6. Engine is set overly rich, RPM and power are down somewhat from
peak, excessive smoke from exhaust.
7. Engine is set way too rich, power and RPM are way off peak. Excessive
smoke is seen and engine is cutting out. (breaking into 4-cycle)
8. Engine is set sloppy rich, into a four cycle mode. Engine is no longer
exhibiting two cycle performance, power and RPM have dropped to
where normal flight maneuvers cannot be performed. Raw unburned fuel
is misting out of exhaust on every other revolution, smoke is excessive.
__________________________________________________ _________
This is where I draw the line. K&B calls this point "slightly rich".
I disagree with K&B's assessment, or description of rich running.
Trying to define stages of richness past this point is moot, because
not only is power down to the point where flight is becoming unobtainable
the plug is going to drown, and the engine will quit anyway.

Keep in mind that a two cycle engine running wide open can ingest
an astonishing amount of fuel, and keep running. A four cycle motor
cycle engine will not run past the #5 area above. It will cut out and
misfire, just like it has an ignition problem.

If one was to take K&B's silly assessment of engines running in a stage
9 or 10 in my example....how would you "RUIN" an engine that
just died from the plug drowning, and the fire going out ? Who's
going to operate their engine in a ridiculous fashion way past a
four stroke ?

I will state, IMO to say that an engine that is firing every other stroke,
and spitting raw fuel out the exhaust....is running "slightly rich"
is absurd ! [X(]

FBD.
Old 04-14-2005, 08:59 PM
  #22  
Senior Member
My Feedback: (9)
 
Join Date: Dec 2001
Location: Breckenridge, TX
Posts: 123
Likes: 0
Received 0 Likes on 0 Posts
Default RE: New ABC...sloppy rich running

We're talking break in here,not flying.
I'm still going to run my brand new OS 46 AX @ #7 on the bench.
Again,if it breaks,I'll buy another one.
What's the big deal?
We're not talking home mortgage here.
Mike
Old 04-14-2005, 09:02 PM
  #23  
Senior Member
My Feedback: (9)
 
Join Date: Dec 2001
Location: Breckenridge, TX
Posts: 123
Likes: 0
Received 0 Likes on 0 Posts
Default RE: New ABC...sloppy rich running

BTW,
I'm with downunder here.
I found out from my old SuperTiger ABC days that you can run these engines rich,and not hurt them.
Go look at what the control line guys do.
Thats where my training comes from.
Mike
Old 04-14-2005, 09:15 PM
  #24  
My Feedback: (12)
 
piper_chuck's Avatar
 
Join Date: Jun 2004
Location: Columbia, SC
Posts: 8,044
Likes: 0
Received 0 Likes on 0 Posts
Default RE: New ABC...sloppy rich running

ORIGINAL: Flyboy Dave

8. Engine is set sloppy rich, into a four cycle mode. Engine is no longer
exhibiting two cycle performance, power and RPM have dropped to
where normal flight maneuvers cannot be performed. Raw unburned fuel
is misting out of exhaust on every other revolution, smoke is excessive.
__________________________________________________ _________
This is where I draw the line. K&B calls this point "slightly rich".
I disagree with K&B's assessment, or description of rich running.
This is NOT what K&B calls "slightly rich". It is what they call sloppy rich, just like you did. K&B's definition of sloppy rich is very similar, though not as detailed, to your number 8. I've posted it before, no need to repeat it. I will however, repost their definition of slightly rich:

"SLIGHTLY RICH running is a rich type setting, but it is fast enough to pull the airplane. This is the setting you normally look for before launching the airplane because the engine will run leaner when airborne."

I don't know how you set your engines before launching the airplane, but I certainly do not set it according to your number 8, which you said is equivalent to K&B's slightly rich. I set it mine in the 4 or perhaps 5 range on your scale, which most people, including you and K&B, would call slightly rich.

Old 04-14-2005, 09:23 PM
  #25  
My Feedback: (21)
 
Flyboy Dave's Avatar
 
Join Date: Mar 2002
Location: Pinon Hills, CA
Posts: 13,847
Received 5 Likes on 5 Posts
Default RE: New ABC...sloppy rich running

Chuck....you are miss-quoting the factual info that YOU posted from the
K&B site....

"FOUR CYCLING or SLIGHTLY RICH running is a rich type setting, but it is fast
enough to pull the airplane. This is the setting you normally look for before
launching the airplane because the engine will run leaner when airborne."

FBD.


Thread Tools
Search this Thread

Contact Us - Manage Preferences Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.