I agree, Proptop. It's that some readers may take some of the contentions the wrong way, especially if they are new to Engines. Nobody is squelching anything.

Interesting thread.

I will just add that I have not melted an engine in a while

Break in proceedures vary like politicts. The methods I used are documented in many threads.

Bob

You must be reading the instructions that come with your engines......

The problem for some folks as they grow old (me) is that what is said at different times lose their context in time - over time. Admittedly, what I paraphrased in a previous post may have occurred many years ago. Seems like just yesterday to me.

You make two good points, Dar.


Ed Cregger

I always thought a heat cycle type break-in would stress relief parts and do a final microscopic polish of mating surfaces.

Quote:

ORIGINAL: PlaneKrazee

I always thought a heat cycle type break-in would stress relief parts and do a final microscopic polish of mating surfaces.

PK,


As I wrote earlier, the first part of your post; heat treating does not take place at the temperatures the parts of the engine attain during break-in. So it would not be wise to expect them to be stress-releaved to any extent.

The mutual polishing of the moving parts does happen; so sealing is optimized and friction minimized.


EDIT: Typo

There is some advantage to heat cycling, but it is not stress relief. It helps prevent localized overheating. That is overheating at a high spot that is so small it can not be detected by normal observation. It also helps with clearances caused by expansion and contraction of the metal. For example the first cool down period is a good time to retorque the head and backplate screws. I suspect this is what is refered as stress relief in the past. But to an engineer this means tempering.

http://www.pmpco.com/annealing/annealing.html

http://www.riheattreating.com/heat-t...ecialties.html

http://www.tristateflame.com/annealing.htm

Do the temperatures in our engines not reach 300 degrees as you posted?

Here.. http://www.rcuniverse.com/forum/fb.asp?m=10551179

It's a shame when facts get in the way of a good argument...

I apologize if I've upset you.

Quote:

ORIGINAL: Broken Wings

Quote:

ORIGINAL: DarZeelon

Quote:

ORIGINAL: PlaneKrazee

I always thought a heat cycle type break-in would stress relief parts and do a final microscopic polish of mating surfaces.

PK,


As I wrote earlier, the first part of your post; heat treating does not take place at the temperatures the parts of the engine attain during break-in. So it would not be wise to expect them to be stress-releaved to any degree.

The muutal polishing of the moving parts does happen; so sealing is optimized and friction minimized.

http://www.pmpco.com/annealing/annealing.html

http://www.riheattreating.com/heat-t...ecialties.html

http://www.tristateflame.com/annealing.htm

Do the temperatures in our engines not reach 300 degrees as you posted?

Here.. http://www.rcuniverse.com/forum/fb.asp?m=10551179

BW,


Let me first ask you one question... Is it or isn't it the objective of the break-in, to soften the high-silicon aluminium piston, or the chromium plated sleeve?

Since we both know the answer to this question, could you please stop wasting my time, by bringing up the issue of heat treating/annealing over and over again???


And yes; as I wrote, the temperatures of the metals in glow engines, do not often exceed 300°F, so no type of non-ferrous metal annealing takes place; not that it should.

In an ABC engine it's the piston, not the liner that wears to size.

What doesn't make any sense (to me)... If we are talking materials and temperature is when you write;

"Metals do react to heat. But not the metals that our ABC engines are constructed from..." Why is that?

If you feel that I'm wasting your time, Please feel free to move on.

BW,


When you quote me, please include the entire passage: "Metals do react to heat.
But not the metals that our ABC engines are constructed from; and not at the temperatures they reach inside a running glow engine."

If I was unclear, I meant that when metals heat to their normal operating temperature in an ABC engine, because they do not heat up to a higher temperature range, where they can become annealed, it does not take place.
And also, none of us want the piston to become ductile, while the engine is running...

My presence in this thread is, I believe, of importance.

Your questioning regarding annealing/heat treating; because they neither happen, nor are these precesses of any use in glow engines; is simply wasting your own free time and mine.


The question was about the importance of the break-in procedure... If you have anything to add on the matter, please do.
If you want to talk about annealing/heat treating of metals below 300°F; why don't you start your own thread to discuss it.

I will reply if and when I see fit.

The lower temp for annealing is the temp that the process must cool through. The higher temp is the temperature the product must be at or near before the annealing procceswill begin. The slow annealing process for most brass is over 600 degrees and brass will not lose any hardness unless above 500 degrees.

Hugh,


So, also according to your words, heat treatment does not acutally take place during the break-in of a glow engine.

With the exception of the meehanite-steel engines' piston, no size-stablization happens either.


So, in any AB(X) engine, the only objective of the break-in is to achieve optimal part-mating, through mutual polishing...
Maybe the cast-iron ring (in engines with ringed pistons) also needs size stabilization, through heat-cycling; and also optimal part-mating, through mutual polishing.

I think the late George Aldridge knew more about engines than anyone on this thread. I will follow his advise. I owned two engines he fitted, both dyked ringed, both with very strong compression after heat cycle break-in.

Dar,

I'd like to know, what makes you an engine expert? Have you designed/built custom engines, raced or competed?

PK,


I'll begin from the end. No, I have not extensively modified any model engine.
I also never competed, or raced with model glow engines.
I only broke many of them in and overhauled and rebuilt many more, using stock or replacement parts.

That is my experience, from which I learned a great deal (many don't learn).

I did overhaul 38 real car engines and hot-rodded several.

I am no engine expert, but my understanding of their dynamics is probably a lot better than the next Joe.
If you read [link=http://www.rcuniverse.com/forum/m_1850473/tm.htm]the tapered-bore break-in thread[/link], you'd see it compiles techniques written by; among others, the persons you mentioned in your last post.


As to heat-cycling; do you actually think alternating the temperature of a high-silicon aluminium piston, from 150°F to 250°F and back, constitutes 'heat-cycling'?
I can tell you it has no effect whatsoever on the metal. You can search any text book, or professional web site that you like; and you still won't be able to refute my words.

These words 'heat cycling', when used to 'typefy' a break-in procedure for an AB(X) engine, are nonesensical; less than 'buzz-words'.


When meehanite-steel engines are discussed, cycling the temperature of the piston, between room-temperature and ~200-275°F, does have an effect of stabilizing the growth of the piston.
This is also true to a degree, as far as the cast-iron ring of a ringed engine is concerned.

Mmmmm......

I'm going to go pop some corn for this show!

I don't recall George Aldrich claimint any heat treatment other then iron pistons. Heat cycling does not in itself imply heat treatment. As I said before it helps prevent overheating and helps with setting the screws and other parts in.

Here's the deal-sometime's it's hard to keep a thread open and unmoderated if a report or complaint is made about it getting heated up too much. We are getting close here, so everybody go run an engine for a few minutes........

Edit for grammar

I fired up a new SC .15 today, true ABC. I run it rich but not four-stroking, shortish runs are good and helps to avoid overheating while also giving me time to contemplate...

just a small hint, It doesn't take much heat to loosen up an ABC piston and liner assembly " try this yourself with a set by heating in a toaster oven at 100' F . This said, anything in a rich two cycle range will NOT cause any harm to an engine of this type. As Downunder has proven beyond a doubt. All you have to do is avoid a lean condition during the first 20-30 flights. The conrod and crankpin require the mose TLC during the first dozen runs to avoid welding the crankpin to the rod bushing lower end due to lack of oil.

Thank you for the reponse. I do not believe I have refered to heat treating or annealing, I have said heat cycling. I am not going to argue with anyone. I will continue to break-in engines based on thier build and will give complete cool downs between runs. Makes me happy.