nitro stan

i did my TTR.28 similer to this method except i got it up to 220 as fast as i could, and drove the tank empty, put to BDC let it cool to 90 maybe cooler and repeted, as i dorve i would have to start leaning out up top to get to temps up to the 220 range. i did this for 11 tanks and started tuning for power. i only got about 15 tanks in it and it runs strong around 250 to 260*. cold pinch with no glow plug is very sli but compression is still very tight. my dyamite torque start box still has a hard time turning it over, when i shut it down and put my piston at BDC compression is still preety tight at over 200* temps

dmx434343

hmm any one comment on this? i have a engine coming in a few days and there are so many different ways i want to be sure i use the most effient way. I guess running at WOT sounds kinda scary to me even if it is a little rich...

highenergyfireball

That sounds very effective i never heard it done that way. For some reason i think probably the best. Awesome post. I will probably use that method.

Darkfae

I used the method CEN Berd posted, and I've had no problems. Actually the thing runs great. I've gone through a gallon so far.
I was WOT for short bursts minutes after starting the motor for the first time. Just let it warm up, and go.

dmx434343

when you guys are saying wot for short burst are you talking gradually getting up to WOT or just from a stop fully open throttle for 1 second then stop...

j_blaze

i used the trim, click and unscrew.

Darkfae

I was full squeeze on the throttle and let the truck rpm's climb till just about max, then let off, coast around the end of a figure 8, and back on the throttle till high rpm's again, let off coast around, rinse repeat for 2-3 min. Let cool, and do it again.

The only time I ever did the 1/4 or 1/2 throttle nonsense was bringing the engine up to temp.

I went through 5 tanks of fuel using this method. I started leaning the engine after 2 tanks, (approx 5 or 6 heat cycles). Only small amounts, just enough to get her to wind a little more. Remember to start out a little rich, but not crazy rich. You want the engine to get up to 200.

After the 5th tank, I tuned for performance.

Fuelman

My Feedback: (6)

Here's the readers digest version, Its been working just fine for the 40 or so years that ABC engines have been around:

[link=http://www.cooperfuels.com/Break-in.htm]Break-In[/link]

j_blaze

i used the drake method on the d21b and so far so good. took 6 tanks on the box 10 cold and 10 hot cycles and the MASSIVE pinch was gone. i had to heat it with the heat gun to get it to start! it still has mad crazy pinch but you can turn it over with the flywheel. i used another two rich tanks on the track. very impressive engine, i picked a good day too cause all the racers were there on a practice day. i gotta say the sts was no match for the modded rossi's and rb's, maybe with a little modding. temps were jumpy but never over 242, i had some fox gold series plugz that may not have been hot enough, engine quit a couple times.

highenergyfireball

Cen_Berd Thank you for the awesome input! Your right there are so many theories on breaking in these little marvels. That Explanation should be packaged with every R/C nitro Engine. You hooked it up. Good Looks my man.

rhysdejager

this is on a brand new os .18TZ

if i dont prime the fule line it starts, idels, then stall pretty must instantly
if i do prime it, the car reves really hard then goes to an idel then stalls
this happend wheither it was rich or lean, and still died if i turn to idel needle in

when your breaking it in, is it ok to lean it in so it doesnt gargle and hesitate when given throttle?
(ive put through 2 n a half tanks so far)

the first tank i ideled through
the second i drove around the track slows
(as the book instructed)

rhysdejager

i just read the nice long post about breaking in at WOT
and it seems a lot better way to break it in than what ive been doing
do you recomend i start again my breaking in, bring needles back to factory setting and do it that way?
i wasnt heat cycling either, i did it has the book said, idel a tank then drive slowly

what do you guy think i should do?

i dont have a temp gun, how do i know when i should stop and let it cool?

j_blaze

get a temp gun, like $25 well worth it.

rhysdejager

so theres no way around it? :P

muscleflex

when you guys say run it slightly rich near 4 stroking, exactly how many turns on the HSN? factory default is 2.5 turns so how many more turns to get it slightly rich?

downunder

If the engine was absolutely peaked at 2.5 turns then opening it another 1/2 to 1 turn should get it fairly close to being rich enough to 4 stroke. The sound is unmistakeable. I like to approach from the much too rich side rather than risk being too lean for even a moment.

muscleflex

^Thanks. mine is at 2.75 turn at the moment..so i might add another half to that to make sure so i can WOT for a bit when i continue breaking it in this coming weekend. :-)

rhysdejager

im using your method, the engine starts and runs
when you give it half throttle it goes and puffs out lots of smoke
but at WOT it dies, so a leaned it in a 1/4
is this ok?

*FULL-REVS*

this meathod makes perfect sence.... and quite honestly dont know why i didnt think of it...as my little brother runs a GP125 2 stroke race bike he rebuilds his motor for every round... when breaking in he tapes the radiator up to get his engine temp up...richens the hell out of his settings and then runs at WOT for 3 mins or so then lets the bike cool to ambiant temp.... and repeats this 6-10 times... people like cen_berd make sites like this what they are....thanks alot

telejojo

I break allmy airplane engines in on a stand WOT at peak until it getshot and back the needle back until it 4 strokes and cools down and then back to peak until it gets hot again and back to rich for 2 or 3 tanks or a gallon on a supertigre and have never had a problem,Engines run strong and idle great.You have to get it hot and lean to mate the parts,rich does nothing but lubricate everything so much it can't wear in.

brisbane010203

Does the same principle apply for the largescale gas engines

j_blaze

if you can adjust the mixture fron the drivers seat, yes.

ShoestringRacer

Cen Berd, your post #25 here about break-in was written by me several years ago here. I have posted it in full several times and in part in response to various break-in question threads. Here is one of them from 2004. See post #7:


http://www.rcuniverse.com/forum/m_16...tm.htm#1751444


I also posted it more recently and in slightly revised form to read better this past June '07 under my other user name here, wantsaneagle. See post #28:

http://www.rcuniverse.com/forum/m_58...tm.htm#5952276



I am glad to see it is being used, passed along, and understood by at least some people! I wrote it up after researching it because it seems impossible to get people to stop idling their new engines, to only lead to wrecking brand-new engines or drastically shortening their engines’ life span. (I also wrote it up because I destroyed my first nitro engine’s piston and sleeve by idling tanks from reading all the wrong advice online from people that didn’t know any better. They taught me lots of things - EXCEPT how to properly break-in, treat and understand a nitro engine!)


I see you joined here this October. Did you find my break-in write up here on RCU or has it made its way to another message board?


Here it is again with a few revisions since my June 2007 post under wantsaneagle:


Idling an engine, or letting it run slow during break-in, and 1/4, ½ throttle is all incorrect. You want WOT (wide open throttle) after it warms up. YES WOT, even when it is brand new. Although you want it on the rich side at this early stage. WOT is in order to bring it up to the temperature and fit that the sleeve was designed to run at. Anything less and you are just leading your engine’s piston and sleeve to an early death.

Yes, running at WOT slightly rich, but not 4 stroking rich is the proper way to do it. The following explains the proper way and WHY it is the proper way. Here is some further explanation I wrote a while ago for newbie nitro guys that were still doing that incorrect idling method:

As for break-in, there is a whole lot of misunderstanding about this and basic engine operation. I have read and studied a lot of information on this and also by Dave Gierke who writes in RCCA and Model Airplane News (also by AirAge) about RC airplane and buggy nitro engines and he's an expert. As well as Paris Racing, Stephen Bess, Clarance Lee, etc, in the research I have done over the last few years. It will take some time to convince yourself to bring a new engine to WOT but when you start to understand it and why it is correct, you will realize just how many people are completely breaking-in the engine totally incorrectly.


It’s important to learn the theory about how these engines run (2 stroke ABC, ABN, AAC - we are not talking about nitro ringed engines here which are different and therefore broken-in differently), and how to break-in, especially because I see WAY TOO MANY people using the wrong procedure of idling many tanks of fuel through the engine or running it very slowly during break-in. That is unnecessary and damaging which I will explain. Although we use the term “break-in”, by its word alone it is misleading because people wrongly assume it means to slowly and gradually bring an engine to tune by idling tanks of fuel but you will see why this is incorrect and unnecessarily wastes fuel too! Please be patient and read further to understand.

These engines use a sleeve around the piston to make the seal (piston doesn't have a ring) and it operates properly only with sufficient heat so that the sleeve can expand to its designed operating size and fit. (these engines are also referred to as “tapered bore” which implies their lack of a piston ring to seal the combustion chamber) All engines will be tight - that’s what people call “pinch”, especially when new, so on the initial runs, you want to have it get up to temp, so it can run how it is was designed to. By the engine getting hot the sleeve expands to the size it was made to run around the piston - properly sealing the combustion chamber for operation. When it is not running it is contracted more and the pinch will be more noticeable (the engine really shouldn’t be turned over without the purpose of starting it to prevent excess piston/sleeve wear). The pinch is what allows the cylinder to have compression because there is no ring on the piston to seal the combustion chamber.

By idling tanks and tanks through, or running overly rich and cool, the sleeve just wears MORE against the piston because it is not hot enough to expand to its operating size. Idling is cool operation, cool means the sleeve doesn’t expand, if the sleeve doesn’t expand, the piston just grinds away against it, destroying the ‘pinch’ which wont allow any compression. Even 1/4 or ½ throttle wont generate enough heat to prevent excess wear and/or help the break-in process. And by doing that you are prematurely wearing out and ruining your engine. The piston/sleeve is designed to operate at running temps. Not letting this happen by running cool and rich on the bench leads to premature wear. By idling away tanks of fuel I GUARANTEE you are doing more harm than good. As long as the engine is warmed up first, you don’t have to drag out bringing it up to temp when it is brand new. It wont hurt or damage the working parts. These engines are very simple 2 stroke machines. They do not have extensive moving parts such as valves, cams, lifters, springs, etc. or even piston rings (like 4 strokers) so all this extra gentle, overly rich, cool operation is completely unnecessary (and worse it’s harmful and will decrease the piston/sleeve life).

(in fact back when these ringless, tapered bore engines were first developed and used in airplanes with control lines attached, they didn’t even have carburetors, they were fixed at permanent WOT; in fact these engines are ideally suited to WOT operation all the time. Throttling them only lets the temp decrease and lets the sleeve contract, but the ideal condition for an ABC, ABN, or AAC tapered bore engine is the engine running at WOT operation.)

HOWEVER, the sleeve around the piston can be a delicate thing to maintain and it is not forgiving of improper treatment. The break-in is the most critical time when the most damage can be done by improper operation. And improper treatment of a piston and sleeve by running it at a temp it is not designed for is damaging. (either too cold or too hot, both are just as detrimental) Most often this is done by running it too rich which makes it too cold because the rich mixture doesn't generate enough combustion heat for proper sleeve expansion. Just as damaging can be an excessively lean run. If it is run overly lean for any length of time it will destroy the sleeve. (that is why fuels with castor oil as part of the lube mix are very good because they better tolerate the too high heat of a very lean run and will help to save the sleeve if it is not run too lean for too long. Avoiding an overly lean run is essential when you know enough enough about engine tuning to avoid it. Racers typically run very lean to get the most performance but their piston/sleeve needs more frequent replacement as well)

Running a 2 stroke engine slow and rich makes it '4 stroke' which means it fires every other revolution, and that generates even less heat. ‘4 stroking’ is indicated by that ‘burbling’ or stuttering, hesitant sound instead of the crisp clean ‘whine’ when it is running 2 stroke as designed. It causes damage and wastes fuel as well! Using a fan is absolutely not necessary on it. Most important is to 'heat cycle' the engine about 5 to 10 times to relieve the parts of manufacturing stresses. The heating to running temp and the cooling is what relieves the metals which is what the break-in really is. HEAT CYCLING REALLY IS WHAT BREAK IN IS ALL ABOUT. (I even think break-in should be called “Initial Heat Cycling” instead so that people understand what and why they are doing it.)

But heat cycling doesn’t mean 1/4 throttle runs or bench running with the tires spinning which doesn’t allow a load. (it is much easier to break-in a car motor on an engine stand with a properly sized propellor but doing it in the car is ok if done properly)

You run the engine in the car for 2 - 3 minutes at a time going to full throttle on straight line passes (yes, WOT, don’t baby it), ideally on a smooth paved level surface, after briefly warming up of course, and then shut down and repeat after the engine has fully cooled. Let it cool down completely. Heat cycling is the name of the game. You want it to come up to temp for a brief time - 2 to 3 minutes, and cool down and repeat. VERY IMPORTANT: after shutting down, adjust the flywheel so that the piston is at BDC (bottom dead center) so that it does not get stuck in the contracting/cooling sleeve, as can often happen. (If the piston should accidentally get stuck in the sleeve, heat the cylinder with a heat gun or hair dryer which will expand the sleeve to free the piston from the sleeve.)

During these initial runs YOU WANT the temps to be at least 200 F but not above about 250 F. But don’t get carried away and overly focused with temp gun readings - people often times chase their tails with temp guns because of variables of readings and also it’s really not that necessary. As long as you see a good amount of blue smoke from the pipe you know you are running rich enough. After break-in, running temps above about 250F is fine. (In fact nitro engines perform best when run 250-300. Below those temps they are less efficient and less powerful and more wear is occurring to the sleeve and piston because the sleeve is not fully expanded. However, going by the mixture is more important than trying to measure temp, etc. which you may wind up doing inconsistently. The mixture setting on the High Speed Needle (HSN) is critical in the first runs. It should be a rich and not lean setting. However it should not be so rich that it 4 strokes. - 4 stroke operation means the excess fuel causes the glow plug to ignite the mixture every other stroke and is defined by a very burbling sound when running. (Yes, two stroke glow ignition engines can “4 stroke” in the combustion cycle contrary to what you might think. It is very easy to hear this when you have the engine on a stand and can hear immediate changes to mixture adjustments) (the stock instruction book settings are usually quite rich and may need leaning on the first runs from book settings)

Also, to start a brand new engine it is sometimes worthwhile to heat the engine with a heat gun or hair dryer if it has a very tight piston/sleeve fit and you are having trouble turning it over to start it up. This will expand the sleeve some, and when you turn it over the piston will not excessively rub, or even get stuck in the sleeve (as sometimes can happen). Preheating really works well. You do want to run it on the rich side, but you want it to come up to temp also, just not more than 2-3 minutes in beginning runs, in order to keeps temps around 230 - 250. Listen carefully to the exhaust noise or ‘note’, as you do not want it to be ‘4 stroking’. If it is, it needs to be leaned slowly until it runs 2 stroke. You can tell it is 4 stroking if it is very “boggy” and “hesitant” in acceleration and running. If it is making that “burbling” sound then it is 4 stroking which means it is running too rich and therefore too cold. If you are getting boggy and burbling sound when you go to WOT turn the HSN very gradual increments and you will hear it at some point clear up with a clean 2 stroke sound.

Everyone thinks they have to run it super cool and check to be sure temps are low. That's not what it is about. The reverse is true! Cool operation is damaging operation. Little, if any, break-in will occur unless it is heat cycled properly.

The manufactures can’t make a piston/sleeve turn over smoothly at room temp, because when the engine runs the sleeve will expand and there will be no seal at operating temp. See how that makes sense?!

So preheat it if necessary and don't run it cool, and heat cycle it, and you'll be good to go! After you have done this several times then you can gradually lean out the HSN to get best performance, but it should then be richened up just rich of peak to ensure it lasts long too. Running it at max peak rpm will lead to the shortest useful life of the piston and sleeve. If racing that is fine but if you are just playing and bashing you may want to run just a little richer than that peak setting. Racers pistons and sleeves don’t last nearly as long because they race them so leaned out to get best performance, but you cant do that too long. After the HSN is set then it is time to set the low and/or mid range needles and idling setting.

I see a lot of people idle the engine for a tank and then they let it cool off thinking that they are "heat cycling" it. However, because they are not running it up to WOT it is not generating enough heat to be of any use to a breakin/heat cycle. So, inadvertently by idling they are just letting the engine sleeve and piston wear and grind away the taper at the top from the cold tight fit that they are allowing to happen when idling away on the bench. Research has shown that basically no break-in effect takes place AT ALL unless the engine is allowed to come up to operating temp and for at least 2 minutes. So if you are idling away and then let it cool there is zero break-in/heat cycle benefit. But if you want to wear away the sleeve and piston fit and therefore wreck an engine, then prolonged idling will definitely do it for you!

As you do several 2 - 3 minute runs, you will see the engine come alive right before your eyes. It will respond to throttle quicker, accelerate better and show its power right in front of you.

So to paraphrase a proper break-in is:

Run the engine for at least five 2-3 minutes runs bringing the engine to WOT passes during those runs. Let it cool down between each run and make sure you move the piston to BDC by turning the flywheel manually.

If you use that (proper!) method you will quickly, properly and efficiently break-in a new nitro ABC, ABN, AAC (non-ringed) engine. You wont waste time, effort, and fuel by mindlessly letting it idle away destroying the piston and sleeve.

I hope this is helpful!!

P.S. If you want to hear it from him, read Dave Gierke’s article in the January 2002 issue of “RC Nitro” magazine!

j_blaze

2 gallons, still kicking, woohoo!!

j_blaze

broke in the second sts d21b today. took about 30 minutes, 1 bottle+1 tank full, temps were 190,200,210,210 and 220 with 140's in between. loving the drake method so far.