Flyboy Dave

My Feedback: (21)

Did anyone notice any similarities in what the author of the diesel tutorial said,
and what I said ? We are both talking about rubbing cast iron and steel together
in small aero-model engines.
__________________________________________________ ____
__________________________________________________ ___


The rules for Vintage diesel combat require the use of a non-schnuerle .15 cu. In.
diesel motor (plain bearing or stock PAW .15 BR) having a cast iron piston running
in a steel sleeve. We call this a ferrous piston/cylinder set-up, since both cast iron
and steel are ferrous metals.
_________________________________________________
Me:
For all practical purposes, lets assume that the engines we talk about have
plain steel cylinders, and cast iron rings.
__________________________________________________
2) Start the engine and run it slightly rich and a touch under compressed (smoky
and missing slightly ) for 4 minutes or so.
_________________________________________________
Me:
Shouldn't you warm up the engine for a minute (like you
would any other motor) then bring up the rpm's and let the parts expand to
their normal running clearances....which BTW, the manufacturer has gone to
great lengths to assure are correct.....then adjust the carb so the engine is
running correctly....and not over heating ?
__________________________________________________ ________
(3) Keeping the engine running, adjust the compression and needle valve for
fastest speed (leaned right out).
__________________________________________________
Me: OK, I only warmed my engine up for one minute.
__________________________________________________ _

The purpose of this is to get the piston as hot as possible to help it to grow
to its stable dimension as discussed above.
___________________________________________
Me: Yes, I discussed it above as well.
________________________________________
(4) Allow the engine to air-cool slowly but completely before restarting
_____________________________________________
Me:
Two five minute runs, with a cool down in between....and the engine is ready for business.
__________________________________________________ __________

Run it like this for one minute maximum, then stop the engine .

5) Repeat this process a minimum of 8 times or until the motor feels nice and
smooth throughout the stroke when turned over slowly. At this point, the
motor can be flown.
_________________________________________________
Me: OK, he says 8 minutes....I said 10 minutes, and he's talking about
racing engines.
_________________________________________________E nd
_________________________________________________

I didn't see anywhere where the author said to run the engine sloppy rich
for hours and hours, gallon after gallon. As a matter of fact, the procedure
for breaking in those cast iron pistons has undergone the same myths as all
the other engines on the Internet. After these silly stories are repeated
enough times, the become Internet fact....when in fact they have no basis
in truth whatsoever.

Which brings us back to the pretense:

"ringed engines take a very long time to break-in".

False. The cast iron ring and the steel cylinder liner begin the surface
mating operation instantly....and satisfactory bedding-in and normal
compression is attained in a very short time....10 minutes in my estimation,
if the engine is allowed to attain normal operating temperatures.

If the engine is run too cool, or run way too rich....it will take considerably
longer to break-in.

FBD.

DarZeelon

Dave,


Diesel model engines are very different from glow engines.

1. Their fuel typically contains much more lubricant; 25-30% Castor oil.

2. Their main combustible component (kerosene) also has lubricant properties.

3. When set too rich, a Diesel model engine will not 'four-cycle' as a glow engine would, and will not run cooler.
The sheer volume of the fuel will actually make it over-compressed and may even cause it to overheat.

4. When set too lean, a Diesel will never pre-ignite, or detonate, as a glow engine would. It will just mis-fire and will do it more, the leaner it is set.

5. Diesel model engines run significantly cooler than glow engines, so the MVVS .61 ABC Diesel comes with a glow head for break-in, that is replaced by the Diesel head, once you're done with this stage.
Otherwise, the colder Diesel running temperatures would inhibit a correct ABC break-in.

6. Despite the structural similarities of most smaller Diesels, to some ferrite glow engines (ring and piston) and due to the above facts, the recommended break-in technique for these Diesels has no practical bearing in this discussion.

Sport_Pilot

[ There is small amounts of oil in all gasoline, it is actually not a very refined distillate. When I say refined I don't mean octane, which has nothing to do with the refining process. I mean it has a wide range of thin or thick distillates, from a light oil to thin distillates. Only paint thinners and aircraft fuel is highly refined. Oil will not necessarily have a higher hydrocarbon reading, as oil is a longer molecule chain, it does not necessarily contain more hydrogen or carbon.


Many manufactures of the cheap weed whackers will not allow a ratio of more than 50:1.

Because the tolerance of rings and cylinders vary, the ring will be slightly oval shaped when in place, most of the break in is to allow the ring to mate into the cylinder and get rid of the gaped at two sides of the oval shaped ring. The exception is when the ring is honed to fit each cylinder as is done on many racing engines, especially drag engines, which may only get a few minutes of idling and a pumped throttle for a break in. Break in on a car can take thousands of miles, but initial ring seating takes minutes not seconds.

Flyboy Dave

My Feedback: (21)

Sport Pilot....

...I worked as a precision engine rebuilder full time for 15 years. I also did all
the cylinder boring, honing and ring fitting in production and racing engines of
all types....mostly two cycles. I don't know where you get your information,
but I know one thing for sure....

....if your rings are fitting "oval shaped" on the cylinder wall....tell the man you
want your money back.

Flyboy Dave.

Sport_Pilot

Take a ring out of the box and compare it to a circle. It may or may not be round, now pinch it till the gap is closed and compare it again. Many rings will be very close to a circle, some were closer to a circle out of the box. Now don't tell me it is a perfect circle for all ring gaps, cause it is impossible. You may not be able to tell the differance with your naked eye, but it is not the same.

Flyboy Dave

My Feedback: (21)

Rings are checked visually by pushing the ring into the cylinder, then pushing
it in a bit more with the piston crown, which will align the ring perpendicular
to the bore and straight. If you can see light between the ring and the cylinder
wall, the ring is not round, and should be replaced with a round ring.

That's the way it is....like I said., I bored-out cylinders and fitted rings every
day for 15 years.

There is no such thing that I know of what you said...."honing the ring". The ring
either fits, or it doesn't.

FBD.

Sport_Pilot

The fact that you can not see lignt does not make it perfectly round! You cannot see this with your naked eye! In fact most rings will be touching the wall all the way around, but with varing pressure.

ICE_MAN

Welp Might as well jump in with my experience..

I've broken in and run a couple Ringed engines and have 1 employed and one temporaril without a plane.
I took my sweet time breaking in both engines... Neither really rich.. But I tuned them for good transition and at the same time plenty of smoke..4 gallons through my ST 1.40 and it gained power and RPM every run still with the smoke trail...Then I leaned her out to peak and backed off the RPM's (500 to be exact)...

It now has more than 14 gallons through it and it starts 1 or second flip EVERY time, holds a tune great... Capable of turning an 18X6 at about 9,500 RPM Leaned out and easily tunrs 9,100 with a good smoke trail..

Probably the best running engine at our field with the least amount of fuss and gobs of power.

If you try to break in a ringed engine in 10 minutes then your engine will not last and will not hold a tune... Will not be reliable..

Flyboy Dave

My Feedback: (21)

The initial break-in on a ringed engine that places place very rapidly, doesn't
mean that additional bedding-in doesn't take place in flight. Initial break-in starts
the very second the engine fires up. Some Guys prefer to finish the bedding in
of the engine while flying it. Others may prefer to spend a couple hours or even
longer on the bench, infuriating their "favorite neighbors".

I contend that a lot of this time at the bench is wasted time, and wasted fuel.
Running the ringed engine sloppy rich is actually hindering the break-in process,
not helping it. How many times have you read where a Guy spent a couple
gallons of fuel on the bench, before the engine started acting right, or would
idle properly ?

I contend also, that once the engine leaves the protective custody of the engine
stand and enters the real world....that time will have very little if anything at all
to do with the longevity of that particular engine. Now the engine is going to be
subjected to all kinds of awful things. Heat, vibration, accidental lean conditions
that get the engine hotter than a pistol. The treatment the operator gives the
engine in the plane, as well as the fuel, oil, prop, muffler, cowling, ect.....not to
mention the careful tuning of the engine has all to do with how long the engine
will last....not what happened in the garage a few weeks ago.

The manner in which the engine is operated might have something to do with
it as well. An engine that is blasted back and forth in dives, full throttle, screaming
for every last RPM might not last as long as an engine that never really got much
over 2/3 throttle in it's life. One might go 10-20 hours, the other might go 100-200.

I've had pretty good luck with the ringed motors, running them since '69. I get about
15 years out of a ringed engine....if it stays in one piece.

This OS is a good example of a "once every 15 years ring-job".

FBD.

ICE_MAN

"I contend that a lot of this time at the bench is wasted time, and wasted fuel.
Running the ringed engine sloppy rich is actually hindering the break-in process,
not helping it."

Did I ever say I took my sweet time on the bench?? I ran about 5 tanks through it on the bench for around an hour... To get her tuned in and idleing properly.. Checking the engines vital signs ETC.
Then I threw her on the plane for the rest of the time! I just made sure to take it easy on them keep a good smoke trail.. Didnt fly it hard.. No Highspeed flying, no hovering etcetc.

Since yor compare to GAS two strokes.. (Motorcycles) How do alot of guys break in there gas plane engines? On the plane, slightly rich, takin it easy!

Rupurt

Nope they fly them, the guys who no things about rc gas engines say that altough the rings will bed in after some time running its a waste of time running them on a bench, unless of coarse there is a problem with the engine.

ICE_MAN

Rupurt.

I said on the plane.. Which mens FLYING them..

And as i stated the only reason I ran mine on the bench was initial set-up

Rupurt

Sorry, I tought you were asking.[8D]

ICE_MAN

What We have here is communcation failure

No Worries![8D]

laker500

My Feedback: (2)

Hello,
I have something that fits this discusion. In a previous job I did alot of work for the county. While working at the county's ambulance garage I had alot of discussions with the head mechaninc there. I remember discussing the ambulances and how they required engine overhauls quite often. I figured it was from the way they were driven but was corrected by being told it was from the way they were idled. The engines were all diesels but because they spent so much time ideling they would polish the rings and cylinders to the point they would no longer seal properly. And as someone had said before they lost compression and burned lots of oil. They would have to tear them down, replace the rings and hone the cylinders. So I am convinced we need to do some running in but then fly it like it was designed to be flown. Overheating an engine that was run for hours will still likely ruin it and to rich keeps them to cool to work properly as well. To much break in time I dont believe gets you alot but none at all gets you less. I think we should pay more attention to temperatures of the engines and then just fly them. Jeff

jessiej

Predicated upon the number of "right" ways to break in an engine there must be only a very few properly functioning model engines in existence.

jess

Jarsu

About the "hard break-in" for motorcycles etc. mentioned on the first page in this thread, [link=http://www.mototuneusa.com/break_in_secrets.htm]this link[/link] explains the method quite well. I quote the most important factor in this method: "How Do Rings Seal Against Tremendous Combustion Pressure ?? From the actual gas pressure itself !! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into
the cylinder surface, to seal the combustion pressure as well as possible.
" If this isn't done in the first moments of operation, the honing wears away from the cylinder without wearing the ring to match it properly due to too low pressure behind the ring.

I don't see why this shouldn't work on ringed model engines as well. So how to adopt this to an airplane engine? To build the pressure, one could do a vertical upline with full throttle, and for the cool down period, come down with the engine idling. So this is how I would do it: run the engine on the ground up to the point where I get it to run reliably (this depends on engine) but for example for an YS 4-stroke this would be a few minutes, then adjust the engine a little rich and go flying!

Having said that, with all the oil in model engine fuel, the proper seating of the ring can't be as big a factor in a model engine than it is in a car or motorcycle engine, the oil itself acts as a seal as well.

Flyboy Dave

My Feedback: (21)

JTS....[sm=thumbup.gif][sm=thumbup.gif]....

....two thumbs up for that review. That mechanic knows the same stuff
that I learned many years ago. I was fortunate as a young man in the mechanical
world. One....I grew up in my fathers automotive (commercial) garage an did all
the engine over-hauling and rebuilding from my age of 17, on up. And Two....when
I entered the motorcycle field at a Yamaha, Norton, Montesa, Hodaka dealership
I was blessed by the fact that the service manager was a professional AMA m/c racer,
and was the Pres. of the San Pedro M/C Club....which I was the youngest member,
and the parts manager (also in the club) was my best friend, and a m/c engine
builder. They took me under their wing, and taught me everything. The S. P. M/c
Club was a racing club in district 37 of the AMA, not a street club, although we did
of course have a few street riders....Triumphs and BSA's mostly. I rode a BSA to
High school.

Well....what do m/c engines have anything to do with our Aero-model engines ??
The short answer is.... with a very few exceptions....all internal combustion engines
are made with the same components, and are made out of the same materials.

Well then....what about the fuel, we use methanol (alcohol) ??
It doesn't matter what the fuel is....the fuel by itself doesn't lubricate the engine,
nor does the fuel by itself dictate the break-in procedure.

The young man in the review stated what I said, in that....the break-in starts the
instant the engine is fired up. The rubbing between the piston and ring (the bedding
-in or mating) doesn't last long.

Later if anyone cares, I will explain why a motorcycle technician is like 10 automotive
experts rolled into one, and give my secret technique for engine break-in....as well
as the reason why, and how I learned this technique....in 1965.

Right now I have two projects going....doing some ducting work to improve the
cooling on the variable drive on a new motor scooter (4-stroke) and finishing up
a Delta Vortex airplane.

FBD.

olstoney

My Feedback: (19)

Guys,
Dave really has his act together with his advice believe it or not, just my humble 2 cents worth. As one who has built NHRA drag racing engines for some time ( over 30 years), rings seat much more quickly than you think unless they are chrome, right Dave? That being said, we run 80% nitro at over 300mph with no water cooling at around 4.9 seconds or less in the 1/4 mile. The best part is we get to rip these engines down after every run to rebuild them in 45 minutes or less. That's of course unless we just blow them to smitherines on 80%. It's nothing more than a controlled explosion just waiting to happen[>:]. Single or twin cylinder model engines are just not that difficult. Just ask ex Top Fuel Champion Eddie Hill or Unlimited Hydroplane racer Dave Villwock who both fly pattern with YS four strokes.

jessiej

So did I! (1959-1961) Marked me as a hoodlum, yet I got none of the benefits Brando got.

jess

Flyboy Dave

My Feedback: (21)

Right on, Jess....life was good back then, huh ? A nice motoorcycle to ride
and a pretty girl to take to the dance on Saturday night.

Dave.

laker500

My Feedback: (2)

Hey Dave,
I would like to hear your super seceret technique for breaking in model engines. I am also interested in why it takes 10 bike mechanincs to fix a car as well, or whatever it was that you said.. [8D]
Just giving you a litle static there Dave, I am interested in your break-in steps though. Jeff

Sport_Pilot

This is what I was trying to say.

Flyboy Dave

My Feedback: (21)

I'm not going to bother writing a novel here about what I have learned in my
lifetime about engines. You know, there are lots of young enthusiasts who
are eager to learn everything they can about engines and such...and will
absorb every word the old mechanic says. They value the experience. Then
there are the guys who fiddled with a thing or two out in the garage, read a
couple articles about some mechanical device....get on the Internet, and pretend
they have a clue....nit-picking the old mechanic, and even arguing with him about
things that are just plain fact.

Here's a couple paragraphs I stole off that young mechanics motorcycle site.
__________________________________________________ ___________

Cognitive Dissonance

Psychologists know that when people are confronted by information that goes
against their pre-existing ideas, the result is cognitive dissonance, a sort of "static"
in the thinking process. It doesn't matter how smart a person is ... cognitive
dissonance occurs in highly intelligent people !!

When someone receives information that is opposite to what they think,
cognitive dissonance can discredit that information, so that the person won't
seriously consider it. In fact, if a new idea drastically opposes one's previously
held ideas, the threatening info won't enter their consciousness at all !!! The
idea becomes simply 'unthinkable' that it could possibly be true, even with things
that are totally obvious to an outside "impartial" observer.

Cognitive dissonance is a primitive, yet amazingly powerful self-preservation
mechanism which can completely override the natural human desire for truth !!!
It's also the main reason that it's so hard for some to re-think new ideas about
how horsepower can be achieved.
__________________________________________________ _________

I couldn't have said it better myself.

Flyboy Dave.

downunder

Cognitive Dissonance
You won't hurt a new ABC by running it in a rich 4 stroke.


Sorry, I couldn't resist