Khizer

Hi Guys,

I have read a lot of posts that says during running-in don`t 4-cycle 2- Stroke ABC/ ABN Engines.
Well this is not true. I ve 36 OS engines all broken-in in the 4-stroke regimes and all running well. I never had any cylinder peeling either.

I also wrote a letter to OS engines Japan back in 2001 asking about this and they confirmed that peeling of liner is not because of running in 4-cycle regime but due to lack of lubrication caused by synthetic fuel and running engines in dusty environments e.g (areas where sea sand blows as most cases were reported in US)

I use a fuel which is a blend of 20 % pure Caster Oil and 80 % methnol since here in Pakistan Caster Oil is very cheap and hi-quality.When it comes to lubrication nothing does it like caster Oil , its onlt downside is vanish residue.

The Lubrication mechanics inside an engines are Hydrodynamic lubrication and boundary layer lubrication.The shear characteristics of Caster Oil are superb as evident from the Bingham diagram and this is the area where it beats synthetic oils. Since in America most of commercial fuels available are either synthtic or blend with caster they dont offer superior protection at low temperature this is point where break-in is done and peel off may occur.

So the major cause of peeling or engine seizure is not 4-stroke running of 2-stroke engine but it is function of the fuel used.

Just to give you an example of how fine my engines are still running by using this break-in method I am quoting My 61 SF ABC. I log my flights and I ve done 150 flights with this one and it is still running as good as new, turning a MA Race tip 12 x 6 @ 12700 , 80 Methnol / 20 Caster Fuel, Ambient Temperature 15 Celcius, Plug OS # 8 , Elevation 700 '

Khizer

2slow2matter

My Feedback: (1)

Back before I knew any better, I'd follow the "instructions" for 2 cycle breakin myself. I broke a particular engine in sloppy rich--with plenty of castor. Didn't want to hurt it. I ran somewhere between 1/4 and 1/2 gallon of fuel through it on the ground. About the second flight in the air (again, still rich, but not as rich), the bottom of the conrod shattered. I definitely believe that the conrod was damaged and weakened during breakin because the cylinder wasn't getting hot enough to expand properly. The constant high compression strokes at 7000 RPM's during breakin was too much for the conrod. These engines need to get hot during breaking. The idea of rich is for lubrication, not for cooling. If you keep the cylinder head too cool during breakin, you are asking for trouble. JMO. I have since broken in (ballpark figure) 12 to 15 engines--including mine and others--and have not had one single failure. I also have never broken in an engine that rich again.

jaka

Hi!
Your'e right! Running in is not rocket science! If you just avoid some of the pit falls like dirt and running lean our engines will just run and run and....
But the modern synthetic oils we have in Europe are better than castor oil in that they don't leave a lot of residue (black stuff) on the piston wall and combustion chamber.
Try them and you will never go back to "Old castor oil" for ordinary sport engines (Racing engines are a different matter). I do miss the smell due...there is no synthetic oil that smells as good as castor oil.

Regards!
Jan K
Sweden

Hobbsy

My Feedback: (102)

Amen, I've tried to say that for years, I have several AB? type engines that never had a pinch, they have lasted as long as the ones that did. I even had people tell me that converting AB? engines to Diesel would destroy them because they run too cool, not true. My three highest time two strokes, an old Webra .91 ABN, Fox .74 ABC and an Irvine .53 AB?, all converted to Diesel, the only one that had a pinch at the top is the Webra and it still does. A few folks have fussed about OS not having the correct instructions for AB? engines, they needn't bother because it doesn't matter.

downunder

As in when the oil can't be squeezed out fast enough by the pinch it develops enough internal pressure to compress the piston and expand the liner to maintain a clearance.

Khizer, you might be interested to read this experiment I did.
http://www.rcuniverse.com/forum/New_...2875125/tm.htm

DarZeelon

Khizer,


You should also read the thread on general tapered-bore break-in, as linked below.

It is true many tapered-bore engines will sustain no real damage, perhaps even none at all, from a four-stroking, rich break-in, as Brian wrote in the thread referred to, in post #5.

But why take any chances that anything does go wrong, as 2slow2matter wrote in post #2?


A tapered-bore engine is best broken-in as described in [link=http://www.rcuniverse.com/forum/Tapered%2DBore_Engine_Break%2Din_%2D_Upgraded/m_1850473/tm.htm]this RCU thread[/link].

Doing it as described there, at normal running temperature, low load and with the extra insurance of 25% oil, with added Castor, there is absolutely nothing else that can go wrong, as a result of this procedure.

And also, this type of break-in will be completed faster, with much less fuel waste.

If a new engine was assembled un-professionally, with incorrect clearances and badly manufactured parts and something is bound to fail, it will and a 'wet' break-in will not set it right anyway. So, why bother.

Just do a running temperature break-in procedure.


Brian,

This is not right. I personally heard a couple of tight engines, where the piston was squeaking at TDC, while they were running rich and cold. It was audible over the exhaust note.
This is what metal-to-metal contact sounds like. This happens only if the oil film was squeezed out!

Rcpilot

My Feedback: (78)

4-stroking an ABC engine during break in is the worst thing you can do to it. Your confused. Also--4-stroking an ABC during break in is NOT what leads to cylinder peeling. The cylinder peeling is from leaning the needles out too much and getting the darn thing too hot.

The only reason why OS advocates stupid rich settings during break in is because it saves them from warranty claims. If you break it in with a stupid rich setting--it won't seize up or fall apart--but your ruining the compression and longevity of the engine. OS doesn't care about that. They just want to make sure you don't blow it up while doing the initial break in--and then send it back for warranty. How long the engine lasts or how much power it puts out for the end user is of absolutely no concern to OS.

Good for you. Castor is a very good lubricant.

Again, your confused or mis-informed. Rich running is NOT going to make your cylinder peel. Lean running is what makes cylinders peel.

Well, which is it? Now your saying that 4-stroking is NOT the cause of peeling--rather fuel. I think the part about fuel is total BS. As long as you run any commercially available fuel with about 16--20% oil your going to be fine as long as you don't get stupid and lean it out too much

150 flights is nothing. Put another 500 flights on it and then get back to me about longevity. That engine would still be almost new if you hadn't slobbered a bunch of fuel through it while you broke it in. You probably took about 3yrs worth of life out of that engine by not following the advice of all these guys on RCU that have told people time and time again how to break in an ABC engine.

Had you listened to all the guys who KNOW how to break in an ABC engine, it would be putting out more power, and it'll last longer in the end.

My 61FX would turn just about any 12-6 prop at 12,500RPM with 5% fuel and 6000' elevation.


You still got some learnin' to do. Get back to us when you have about 750 flights on that motor and let us know what prop it's turning and how many RPM after all those flights. Nice try though.

Kweasel

My Feedback: (29)

Here's an example of ABC durability. I have an OS61RF in an old pattern plane. It does not have a pump so it must be tuned four-cycling rich with a full tank, at the end of the flight it will occasionally sag lean. This engine gets an extreme range of temperature every single flight, and from the very first tank of fuel. So far the liner is intact and still making great power. I'm sure it helps flying from concrete where little dust is ingested. Unless its an extremely tight engine, like an old Fox or Supertigre, just fly it.

downunder

Dar
It's good to see you've changed your ideas away from your original doomsday prophecies of "Run it rich for even one tank and you might as well throw away your engine" as I well recall you telling one newcomer.

Maybe it's worth repeating that my experiment wasn't to say an ABC should (or could) be run in slobbering rich but only to find out what damage might be caused instead of just going BAAA BAAAAA and following the sheep.

britbrat

What do Aussie girls have to do with engines?

RaceCity

Oh boy....is that an invitation for a classic (ie: filthy) response or what!

<GRIN>

'Race

FlyingPilgrim

My Feedback: (26)

Taper bore cylinders need to get hot in order for the parts to have the right clearance. If you run 4-cycle rich during break-in, you are allowing continued interference fit by not letting the cylincer expand enough from being too cool. That will cause premature wear at best, and as 2slow mentioned, could result in worse. I would not recommend that on a taper fit bore. run it rich, but not 4-cycle rich.

jessiej

I have not had a peeling liner myself, but from what I have read the problem was more due to improper manufacture than either rich or lean running, and was more a problem with ABN than ABC engines.

Hopefully someone more knowledgeable on the "peeling" issue will comment.

jess

Khizer

Rcpilot,

90 % damage to an engine occurs as a result of starting friction ( Taking the assumption that the engine is not run lean or overheated by over proping) when the engine is not wet with fuel.
I wish we had a lube for R/c engines which had polarized molecules to reduce this wear.

Once an engine is running a very thin film of lube 0.05 Micron Ra builds between the cylinder and the piston even though it is taper bore. This type of Lubrication is called Boundary Layer Lubriction.This protective layer consists of not only Lubricant but also methnol and is there as long as engine is running. In four stroke regime a lot of fuel comes from the exhaust in raw form along just fulfilling this duty.

In a running engine assume the piston speed is 10 m/s at this speed if there is no boundary layer lubrication than the metal may wear in micro seconds

A scientific approach to establish something concrete would be to check the compression with the compression guage with two test sample engines; lets say 61 FX`s.One broken-in in 4-stroke regime and the other at higher running speed each using same fule an prop broken-in with 2-litres of fuel and then checking the Compression of each engine.

I assume that the compression ratio in 61 FX would be about 10:1 or so.

Khizer

Motorboy

Khizer

The engine are allready overlubricated (between 15% and 33%) after the engine are primed and very very very little to damage the engine while starting the engine.. I has many modelengines from 1950 to modern engines.. they are still in good contition and good compression.

The castoroil is highly polar and has a great affinity for metal surfaces. Castor oil are better to care the engine than syntetics oil, read here: http://modelenginenews.org/faq/index.html#qa5

Jens Eirik

DarZeelon

Brian,


I did write in the tapered-bore break-in thread that the wear on the piston crown, will be greater if break-in is done four-cycling rich.
I also wrote that ABN engines will be more susceptible to peeling, in these conditions.

This peeling will not happen during the break-in. It is more likely to happen, however, when the engine is peaked-out (or run too lean), long after the break-in is completed.

The interference fit and contact of the piston in the sleeve during a cold, 'wet' break-in, will potentially weaken the bond of the nickel coating to the brass bore.

And...

Load will be imposed upon the nickel/chromium plating, even if no metal-to-metal contact occurs...
The oil-film relays the load to the surfaces, even when it remains intact, as fatigue wear in babbit, Clevite 77 and other bearing materials (in full-size auto engines) would indicate.

So even if wear cannot actually be seen, or measured, it could just be there nevertheless.


I am also saying that even if a four-cycling, rich break-in will cause no immediate visible damage, it is not the best, or even the correct way of doing it.

From your own testimony sometime in the past, you do the break-in of your own tapered-bore engines (and those you are entrusted with their break-in), in a method similar to what is described in the tapered-bore break-in thread.

I am not talking about your experimenting, to prove nothing will happen (...); just about your general practice.

NM2K

My Feedback: (14)

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If your castor lube is leaving black stuff on your cylinder/piston walls, you have inferior castor oil not suited for model use, or you are overheating the engine severely.

When using the proper type of castor oil, you will see NO varnish build up during break-in if the mixture is set properly. The only time that castor leaves varnish is during a lean run, or after a lot of running at normal mixture settings - and I mean a lot. This is why castor is superior to most synthetic oils available for our use.

I am not familiar with your synthetic oil, so I have no opinion regarding its superiority/inferiority and cannot comment in this regard. However, I have used castor oil for nearly fifty years and I can say without a doubt that anyone seeing a severe varnish build-up (light tan) or, worse yet, carbon (black) with little running, is either not using the same type of castor oil that I use to this day, or they are experiencing severe engine overheating. The latter can be caused by running the engine extremely lean, or not lean, but with insufficient cooling air/too much prop load. This opinion is based upon my experience with the castor oil that is sold for model use in the USA only.

I am beginning to suspect, after reading comments from Europeans about castor oil, that their castor is not the same as ours in the USA.

downunder

Which of course is totally at odds with the fact that after 45 minutes of extremely rich 4 stroking (with a head temp of only 145 F) my piston didn't even look as though it'd been run let alone show signs of wear (come on, you've seen the photos of it).

As for my "testimony", without twisting words around, what I said was that because the piston wasn't running in rich and had far more wear when done the usual way, I concluded that an optimal setting would be at or just beyond the 4-2 break and that's what I would use in future.

jaka

Hi!
TheCastor oil we used (got from the AMA )at the 1995 pylonracing world championships at Muncie were leaving a lot of black goo in our engines! Fuel was 80/20 "Riche's Brew"!

I don't think we have inferior Castor oil over here in Europe as we use Castrol M, castor oil. But the fact is, Castor oil leaves a film (black or brown) inside the engine that is constantly building up during time on piston sides and in the combustion chamber...and this is no good!
Using synthetic oil ...or a combination of synthetics and castor oil prohibits all this carbon build up.

Regards!
Jan K
Sweden

NM2K

My Feedback: (14)

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Hold it. Stop the music! <G>

Racing? I'm not talking about racing applications where the engines are stressed with high compression, etc. I'm talking about sport flying with normal engines.

Yes, there will be some carmelization over time, but you won't see it during break-in. And you will not see black build up from castor oil unless the engine is running too hot.

Another application that abuses the hell out of a glow engine, even during normal operation, is in a helicopter. My comments do not apply to any other usage of castor oil than in regular, medium compression, two-stroke glow engines that you will find at any flying field on an average day. No pylon racers, no hydroplanes, no helicopters, etc.

Now, I know that you are an experienced modeler and that you are knowledgable, so don't think I'm trying to discredit you or what you are saying. That would not be true.

jessiej

Jaka, how do you explain the fact that we in the USA do not suffer the alleged problems that seem to plague you when using castor?

jess

cyclops2

The RC glow cars use a hair dryer on the head to slightly expand it on the first few start ups to prevent squeaky starts. OFNA car engines recomends about 260F as a max head temp for + 28,000 in their ABC's.

LEAN over revs cause EVERY dam engine problem.

Flyboy Dave

My Feedback: (21)

Yo, Jess....

....do you think the AMA had the boys running straight 20% castor in the racing
engines for a "reason" ? ( heh heh )

Duh.

FBD.

DarZeelon

Jess,


It could be the 'varnish' and soot that plagues engines in some places is more a result of the gum...

BeNOL from Klotz is said to be 'degummed' as is Baker's AA Castor oil (and also Morgan CleanCastor).

My experience with BeNOL is that it burns pretty cleanly.

Take a look at this MVVS .49 head. It has nothing 'caked' on it and the varnish is no thicker than anodizing.

It has always been run with 20% oil, including between 50-55% BeNOL Castor and/or Castor oil contained in Model Technics Duraglow fuels and has accumulated over 70 hours of run-time.


In the far past, I have seen 'pharmaceutical' grade Castor oil produce gunk and soot, in amounts that you couldn't even imagine...

DarZeelon

Cyclops,


260 degreed Fahrenheit WHERE???

If you measure optically at the tips of the cooling fins, this is very easy to obtain.

If you use an extension thermo-couple, on the glow-plug gasket, to measure the temperature, it will not even idle this cold...


This is barely above the temperature of boiling water (212 F)...