kzmille
05-31-2003, 08:08 AM
RVZoo
Registered User
Posts: 128
(5/28/03 7:35:41 am)
Reply
        How should you break-in your engine.
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Every mechanism need to “break-in”. To make it VERY simple, that means the moving parts that are in contact to each other must “file” and match each other. I think everyone agrees with that, right?
The debate usually goes around the decision to break engines in slowly like the owner manual says or doing it fast and hard like many racers and tuners say. How to take that decision?
Racers and tuners usually perform very fast break-ins because they don’t have the time to do a proper break in. I used the word “proper”. That means I’m getting into hot ground here. Let’s open the worms can: yes guys, the proper way to break in an engine is to run it close to the manual’s instructions and gradually building the way up. That means: if your engine is new, and the manual says not to exceed 6000rpm, do just that. I’ve heard them all: “manufacturers establish those limits so they’ll avoid higher warranty costs”, “they just want to prevent you to kill yourself by driving/riding too fast an unfamiliar machine”, etc. Well, guess what? They don’t. How do I know? Because I am a Design Engineer for a large car manufacturing company. What do I design? Well… Reciprocating Cranktrain components. That is: pistons, ring packs, piston pins and connecting rods. I work in close collaboration with the Design Engineer of the cylinder block. Also with the Test Engineer that designs the break-in protocol and all the tests performed to make sure the components are capable of withstanding what they should. I participate in the writing of the owner’s manuals and contribute in establishing those dreaded upper rev limits for new engines. And I can assure you: we do it strictly from a technical standpoint. No corporate politics there.
Now, let’s explore those limits and understand what they mean. They are NOT un-crossable frontiers. We are talking approximations here, OK? If you need to pass that 18-wheeler and go to 7000 (instead of 6000) your engine will not be “damaged”. You just need to stick “as much as possible” to the rule and avoid steady-state operation.
What happens when I reach that famous 600 miles mark? Now I can go straight to 7500rpm, right? No. Not right. It should be gradual. Increasing engine speed a little at a time until you start using 7500rpm regularly. Same thing when you reach the next mark that “allows” you to go to redline.
OK, then why should I break in the engine gently? Because engine speed determines linear piston speed. And linear piston speed (together with combustion chamber pressure, among many other factors of course) determines ring temperature. Ring temperature is important because it will determine the changes in crystal structure in the ring material. Break the engine in too fast and the ring will harden too much and will be harsher on the cylinder walls filing away the finish in a shorter time. It is as simple as that.
Yeah, sure, but the guy on that web page says all this is bs. Well, to me is bs what he says. If you break in an engine faster, it will surely reach maximum power much sooner. BUT, peak power will be slightly lower and will last A LOT less. If I have to schedule a short engine test, I request a short break in protocol. If I have to test the durability of an engine component, I must request the longest break-in protocol available or the engine will not live through the long test. Race engines are broken-in fast because they need peak power NOW and the engine life will be MUCH shorter than a road engine anyway. Oh, and those pictures in the web page with a beautiful clean piston compared to an ugly dirty one… It’s just BS! You’ll never ever see a piston as clean as that one, coming from a engine that was running for more than a (very) short time.
Cheers to all!
kzmille
Registered User
Posts: 63
(5/28/03 7:56:52 am)
Reply         How should you break-in your engine.
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Engines broken in hard and fast run faster sooner. Engines broken in carefully and properly run faster longer! It just depends which result you're looking for.If you don't keep your bikes very long and you believe all the hype you'll get good results from running it hard. If on the other hand you plan to keep your beloved machine for many years, you will not regret breaking it in with gentle loving care. It just depends which result your looking for.
During the first several hundred miles new engines are sheding wear particles at an ever decreasing rate. One reason to limit RPM during the first 600 miles is to allow this material to be flushed out without doing any more damage than absolutely necessary. Do you really want your new engine turning 10,500 RPM when the largest of these chunks are floating in the thin film of oil between piston and cylinder, plain bearing and shaft, ball and roller bearing, cam lobe and follower?
The biggest myth in this whole controversy is that the rings will not seat if not run at high RPM. I have torn down engines with freshly bored cylinders and new pistons and rings after a two mile easy test ride and the rings were completely seated. Rings will seat as long as the cylinder is round and not tepered. Remember its the combustion preasure that pushes the rings against the cylinder. Opening the throttle is what raises this preasure not high RPM.
This "high RPM", "run it hard" technique comes directly from racing. It is often necessary to have a racing engine ready to race in a very short time period. Racing engines are also often built with larger piston and bearing clearances. Two stroke engines are vastly different in this area because with every intake, power, and exhaust cycle the wear particles are blown out the exhaust.
In the early seventies the S.A.E did a study to determine wheather the common practice of honing cylinders during " in frame " overhauls was beneficial or harmful. They formed two major conclusions. First; after honing, the only way to remove all of the honing debris is to wash the cylinders with plenty of hot soapy water. Not very practical with the crankshaft lying there. If not removed by this method very high initial wear resulted. Second; if the cylinder was within servicable limits, not honing resulted in no ring seating problems whatsoever! Remember its the combustion preasure that pushes the ring against the cylinder.
Since reading about this study in the late seventies I have rebuilt hundreds of car, diesel truck, and motorcycle engines without honing and have had no trouble with rings not seating. In fact, the only time I have ever heard of a ring seating problem in over thirty five years as a proffesional mechanic and machinist was in engines with cylinders that were very badly worn out of round.
RVZoo
Registered User
Posts: 129
(5/28/03 8:27:01 am)
Reply         Thanks
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Thank you KZ.
I think your post goes deeper than mine and teaches me a few things I didn't knew. I'm glad someone with your experience and knowledge agrees to some extent with me and is willing to share that knowledge. Cheers!
DolbyGuy
Registered User
Posts: 42
(5/28/03 1:25:46 pm)
Reply         What to do now???
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Brand new Mille, just about 230 miles on the od.
So, I've just started breaking in my new Mille according to the advice I received on this forum (and through the alleged "BS" web site) and ran the last 50 miles or so at higher revs, occasionally approaching 10.5k in 1st.
I'm not a racer, and I plan on keeping my Mille until they pry it from between my cold dead thighs.
What have I done? Have I #$%ed up my beautiful new Mille? Should I bathe it in warm soapy olive oil while singing the Godfather theme softly into the cylinders?
kzmille
Registered User
Posts: 66
(5/28/03 2:26:39 pm)
Reply         How should you break-in your engine.
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If what you have read above makes sense to you just reread the directions in your owners manual and get back on schedule. And as punishment extend your break-in 100 miles.
DolbyGuy
Registered User
Posts: 43
(5/28/03 2:50:19 pm)
Reply         Are there nasty beasties floating around in my engine now?
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I can't tell what makes sense and what doesn't, as I'm not a mechanical engineer but rather an electrical one.
Most of my gear-head pals agree with the "run it hard" school of thought, but then again they're into the racing thing while I'm just starting out in the SuperBike world.
I want my Mille to run forever, along with a few screaming track days put in there once I learn how to ride it properly.
Wahhhhh!! What do I do? Are there nasty bits floating around in my cylinders now just waiting to lodge somewhere where they'll do the most harm?
Not being an aggressive sort, should I follow the book and keep it down for the next 400 miles?
Is this "break-in controversy" difference a subtle thing that only the demanding rider would notice and then only at the extreme top end?
Should I not sweat it and just go back to the book on this?
Will 50 miles of high revs give me grief?
kzmille
Registered User
Posts: 68
(5/28/03 2:55:24 pm)
Reply         Are there nasty beasties floating around in my engine now?
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Don't worry about it! As I said above just get back on schedule.
DolbyGuy
Registered User
Posts: 44
(5/28/03 3:05:28 pm)
Reply         Back to the book
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Damn. It was fun while it lasted.
At least I've got an idea what it might feel like when I get past the 600 (now 650) mile mark.
What a $#%@$ awesome machine!
DeTuono_
Registered User
Posts: 141
(5/28/03 4:31:40 pm)
Reply         Paging RinOz!
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Thanks for one of the most useful posts I've ever read.
I think one of the reasons for the myth of short break in is that most people get their info from local experts, and most of these are racers. And as 'Zoo and 'Mille suggest, these guys aren't interested in longevity beyond the end of season tear down.
It takes the Internet to get access to the guys who actually DESIGN break in regimes, and WRITE the friggin' instructions in the Owner's Manual. Thanks again guys.
Nick
RVZoo
Registered User
Posts: 131
(5/28/03 4:35:23 pm)
Reply
        Re: Back to the book
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I agree with KZ. Back to the book and enjoy it. Those 50 miles shouldn't make a significant difference in the life of your engine. Have you changed your oil? It could be a good idea, even if you don't change the oil filter. Change the filter too if it makes you feel better.
As KZ suggest, I would extend the break-in period slightly and pamper the engine a little. Let it warm up properly. Avoid steady engine speed. Avoid higher temps (low speed in heavy traffic, for example).
But don't get "stiff". Ride it and enjoy it. When you reach the "marks" increase engine speed gradually.
Are break-in results perceivable? Yes, but that doesn't mean your engine is going to blow. All things being equal, your oil consumption may increase a little bit earlier. It may not. And anyway, earlier than what? Every engine will have oil consumption anyway sooner or later.
Above all, enjoy your bike and don't worry too much. Cheers.
rustie6
Registered User
Posts: 451
(5/28/03 7:35:43 pm)
Reply         Oh BOY....More Break-In!
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Guys, I knew that bringing up the “break-in” subject would be as dangerous as bring up the “which oil is better” subject......you’ll likely get as many answers as there are posts! I’m very surprised at some of the strange comments here, but also surprised at some of the excellent ones as well.
While it is totally true that cylinder pressure is what seats rings, that is NOT the case with pistons. It takes high RPM to scuff and polish all the high spots off so the "non-round" piston conforms as close as possible to the "round" cylinder, but what certainly DOES effect the piston is HEAT! This is not just idle “racers banter”, but from one of the all time experts of piston engines....Gordon Jennings (who just recently died unfortunately). He had performed VERY EXTENSIVE dyno testing in the area of break-in and found that all piston engines responded extremely favorably to the “High RPM, LOW Load” method of break-in. Remember, this is NOT High RPM, High Load.....which could be very bad for a new engine (although most still survive even this abuse). High RPM/Load is “generally” the way most racers break-in their engines....it is indeed a fast way to seat components, but is certainly NOT the correct method!
Although there are many spinning and reciprocating items in an engine to actually “break-in” or “seat”, the pistons and rings are THE MOST important ones. Second on the list are cams and followers, but if NOT properly lubed, these can actually be the first components to fail. Lets just assume that the cam and followers are indeed properly lubed (which is the case in most engines today anyway). The last items in importance to seat properly are the main and rod bearings (in a plain bearing engine). These items can indeed fail early as well, but that would be very unusual. Bearing components are easily kept within a very narrow production tolerance range during manufacture, and have the least amount of “seating” to acquire during break-in.
Also, plain bearings can take a lot of abuse from many small debris while still function perfectly. This is because the relatively soft bearing surface (compared to a hardened crank journal) is designed to literally ABDORB small contaminants. The great majority of ferrous (magnetic) “floaters” will be removed by the magnetic drain plug. The majority of non-ferrous floaters will be absorbed by the filter (that’s it’s job). If the engine is not “making” any major amount of metal, you do not need to worry too much about “floaters”.....unless there is some major internal failure (or the mfgr is a sloppy builder....which I have seen!). So, it is very natural to initially see some ferrous metal on the magnetic drain plug, and if you cut open the filter, you should see some non-ferrous aluminum bits....as well as some bearing bits. What IS very important is that on successive oil changes, these ferrous and non-ferrous contaminants DECREASE. If not, you may have a far more serious problem than the method in which you performed the break-in.
The method of “High RPM, Low Load” seats rings absolutely perfectly, specifically because the gas pressure is indeed elevated behind the rings, driving them into the cylinder wall with just enough force to **begin** the “polishing process”.....but certainly not with enough time and effort to cause a failure. If carried out as recommended in first gear only (in the beginning break-in process), the duration and amount of gas pressure (and cylinder pressure) is very limited in quantity and time.....just perfect for rings = ring face pressure with low heat and short duration.
This method also allows the piston to achieve high RPM with very little heat input....which is ALL the piston cares about (heat). Too much heat will cause the piston to expand and possibly seize in a new, or recently bored engine. If you maintain only low RPM during break-in, the highest rub points may not get the friction necessary to polish them away. This can extend the break-in much longer than necessary, with absolutely NO BENEFITS in engine life. High RPM alone will NOT damage a normal high tech piston. If you were not aware, high RPM failures are rarely caused DIRECTLY by the piston (unless a valve fails first), but are rather from the failure of a ROD. Rod failures occur the great majority of times when at TDC on “valve overlap”, where there is little load from compression to help reduce the rod’s “stretching load” (which is extremely massive at this point).
A rod RARELY fails at BDC (which most people think is the case). The rod is in “compression” at that point, where the its strength is actually the greatest. When at TDC on valve overlap, the rod is in “tension”, and is where its strength is actually the weakest. So...the key is simply to NOT EXCEED the RPM limit. Otherwise, using high RPM in low gears is definitely NOT a danger to the engine....it IS designed to run at that RPM (and is usually governed at that limit anyway).
Then why do the mfgr’s post only an RPM limit and not explain the above dyno proven facts??? Easily answered.....how many new vehicle owners do you think would really understand all this info (even most “bike oriented” individuals)? Not damn many, I’ll tell you!
It is far, far easier for a mfgr to write a short declarative statement, “do not exceed xRPM”. The only problem here is that IF one of these individuals does indeed intend to pass a “lumbering” someone or something by adding more throttle WITHOUT downshifting to prevent going over some contrived RPM limit, you will indeed be lugging your engine, possibly creating more heat than a new piston can withstand, and DEFINITELY increasing cylinder & ring face pressures FAR BEYOND what the same engine would experience if downshifted, allowing RPM to increase. What is KEY and not refutable, is “Load vs RPM”. If done properly, the engine will seat its numerous components earlier, with better results AND longer engine life.....NOT shorter!!! So, just remember: **High RPM, LOW Load**.......NOT High RPM HIGH Load.
As to the condition of the cylinder wall, it only stands to reason that we expect them to be clean and free from debris. Soap and water is indeed one of the best methods to clean newly honed cylinders with....but be prepared to spray a light oil (WD40) as soon as you dry them, or rust will begin almost instantly!
RVZoo
Registered User
Posts: 134
(5/29/03 5:49:42 am)
Reply
        Re: Oh BOY....More Break-In!
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Some things you say are correct Rustie, but you're not taking into account the changes in crystalline structure that high rpm (even at low loads) will cause in the compression rings material.
I am not a metallurgist, so I couldn't go into great depth there even if I wanted to, but I can assure you I HAVE TO request a gentle and long break-in procedure if I'm going to run a durability test. If I go for the higher rpm (still low load), shorter, break-in protocol (we also have that one, as well as other 4 or 5 for different ones for different applications), the engine WILL NOT last (about 99% of the times) for the complete length of the durability test.
Believe me, longer break-in = more money. We are very, very careful about money these days. If I could be using shorter break-in protocols I definitely would. But I would just not get the results I'm looking for.
Oh, and by the way, if I am going to test the maximum power a given engine will deliver, I HAVE TO ask for the long-gentle break-in protocol as well.
One last thing: these break-in protocols are revised every other year, just to make sure we don't use any unnecessary dyno-cell-hour. The suits are always worried that we engineers may be doing things too carefully.
Cheers!
DeTuono_
Registered User
Posts: 142
(5/29/03 6:12:18 am)
Reply         Jennings
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... was one of the good guys. I'm sorry to hear of his death.
From reading his book, I infer that he got his break in info from racebike builders, not roadbike builders. 'Zoo's info still seems valid.
Nick
rustie6
Registered User
Posts: 454
(5/29/03 12:42:26 pm)
Reply         More Break-in
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Zoo,
The "crystalline structure" you refer to is entirely dependent on the type of ring you are testing (including it's thickness and weight). I must assume that the type installed in your test engine is standard gray cast iron......which indeed IS fragile and can be seriously compromised, especially if ring flutter occurs from OVER revving.
The "High RPM, Low Load" concept certainly does not suggest RPM any higher than what the engine was originally designed to handle, so the crystalline structure point is fairly moot.....even a fragile gray cast iron standard ring assembly will not be damaged, changed or otherwise compromised if RPM limits are not exceeded. What you may be dealing with in your testing is very likely specific to the engine type/design in your facility. I don't doubt for one second that you have found specific parameters that benefit your subject engine, but to transfer those unique circumstances to a motorcycle engine with entirely different ring materials and ring designs does not change the beneficial effects of RPM vs Load.....as long as maximum RPM is not exceeded.
As you know, the metallurgical structures all throughout the engine are toughened by multiple heat cycles, so even the most fragile components become more resistant to wear and fracture as the engine is heated and cooled. Properly performed, the crystalline structure of the rings, and all the other components generally get better as the engine ages. So if the testing you are performing is continuous, that may be another reason for your low RPM requirement.
FWIW, Jennings wrote many SAE papers as well. His info and testing was derived over decades of testing just about every engine type and usage imaginable. He did not limit himself to just one area (racing), but I certainly suspect he had his favorites (as we all do).
So goes the controversy!!!!
rsv racing
Registered User
Posts: 69
(5/29/03 1:49:09 pm)
Reply         break in!
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Well, all of your posts sound convincing, and being a computer/electronics expert I can't argue with anyone. So I guess I got the best of both worlds in my break in.....Kept it under 6K for first 650 miles (might have gone over 2 or 3 times at most) but did run it hard during that time. After 650 miles, I got it up to redline (lower gears) but not all of the time, mostly I got it up higher in the RPM as I got comfortable with the bike. Oh well, Its all good.
rustie6
Registered User
Posts: 455
(5/29/03 7:49:54 pm)
Reply         More Break in!
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RSV (and others),
Actually, with the sophistication of todays engines, this break-in stuff is not all that extremely critical in the final "real world" analysis with a stock bike. It can be "important", but certainly NOT seriously "critical". These bikes RARELY run 100k miles anyway....if EVER!!!......
I doubt you could actually hurt one of these Rotax engines regardless of break-in method.....including what I feel would be fairly harsh one = High RPM, HIGH Load.
The current metallurgy, engineering design, assembly methods and machining tolerances of todays bikes are so heavily computer controlled, that nearly every engine produced (especially Rotax) is almost a "blueprinted" engine anyway.
Only MAJOR internal upgrades will make substantial HP changes = Big Bore, Cams and higher compression. Even some of these drastic measures result in only small incremental HP improvements. All the multi-angle valve jobs, porting (NOT polishing), even bigger T/B's will not make much differences until you make the engine breathe deeper = that Big Bore thing, and/or higher compression.....which would be absolutely a BLAST on a Tuono......and my next project
If you break your engine in with either the "High RPM, LOW Load" method.....or the "slow method", I seriously doubt that there would be any pratical differences you would feel with your "BD" (Butt Dyno). Even with a sophisticated inertia type dyno (Dynojet), you would likely see little differences there as well......until you make those "drastic" changes.
THEN.....aftermarket pistons, rings and cylinder bore finishing will become seriously affected by the break-in method because of the increased "variables" now entered into the mix. That's when the "High RPM, LOW Load" method will come in verrrry handy.....
RVZoo
Registered User
Posts: 135
(5/29/03 8:03:02 pm)
Reply
        Re: More Break in!
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I think that's a fairly good point Rustie. And I'll gladly give you the set so we'll stop making DolbyGuy paranoid.
Don't be DolbyGuy! Relax and enjoy your bike!
By the way, since the days I used to drive an Alfa Romeo 33 back in '92 I always said cars should be designed in Italy, but built in Germany. I guess the aprilia-Rotax marriage is something close enough to that... cheers to all.
kzmille
Registered User
Posts: 69
(5/30/03 7:23:03 am)
Reply         More Break in!
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If high RPM low load is the "way" why not do it standing still in neutral?
rsv racing
Registered User
Posts: 76
(5/30/03 8:30:28 am)
Reply         mileage
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Putting 1000 miles or more a week, I hope it will last me 100K miles, I hope.
Gunslinger70
Registered User
Posts: 116
(5/30/03 9:15:27 am)
Reply         Re: More Break in!
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Kzmille, It’s my understanding that that is exactly what happens at the factory after assembly, during the test run, on a partially serviced oil tank, which I gather heat cycles rather quickly. That being the case, I think Rustie is right on point in saying that our method of break-in is not overly critical especially since the most important run (the very first one) was done for you.
Just a couple of thoughts about RVZoo’s assertion that the 6000rpm limit is not corporate politics, it does make a certain amount of sense from a liability stand point IMHO. 6000 RPM’s doesn’t allow for crazy speed and any problems in assembly (chassis and otherwise) would likely show before 600 miles without (hopefully) killing someone or catastrophically destroying the equipment.
On a last note, thanx guys, great posts.
V/r,
Registered User
Posts: 128
(5/28/03 7:35:41 am)
Reply
        How should you break-in your engine.
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Every mechanism need to “break-in”. To make it VERY simple, that means the moving parts that are in contact to each other must “file” and match each other. I think everyone agrees with that, right?
The debate usually goes around the decision to break engines in slowly like the owner manual says or doing it fast and hard like many racers and tuners say. How to take that decision?
Racers and tuners usually perform very fast break-ins because they don’t have the time to do a proper break in. I used the word “proper”. That means I’m getting into hot ground here. Let’s open the worms can: yes guys, the proper way to break in an engine is to run it close to the manual’s instructions and gradually building the way up. That means: if your engine is new, and the manual says not to exceed 6000rpm, do just that. I’ve heard them all: “manufacturers establish those limits so they’ll avoid higher warranty costs”, “they just want to prevent you to kill yourself by driving/riding too fast an unfamiliar machine”, etc. Well, guess what? They don’t. How do I know? Because I am a Design Engineer for a large car manufacturing company. What do I design? Well… Reciprocating Cranktrain components. That is: pistons, ring packs, piston pins and connecting rods. I work in close collaboration with the Design Engineer of the cylinder block. Also with the Test Engineer that designs the break-in protocol and all the tests performed to make sure the components are capable of withstanding what they should. I participate in the writing of the owner’s manuals and contribute in establishing those dreaded upper rev limits for new engines. And I can assure you: we do it strictly from a technical standpoint. No corporate politics there.
Now, let’s explore those limits and understand what they mean. They are NOT un-crossable frontiers. We are talking approximations here, OK? If you need to pass that 18-wheeler and go to 7000 (instead of 6000) your engine will not be “damaged”. You just need to stick “as much as possible” to the rule and avoid steady-state operation.
What happens when I reach that famous 600 miles mark? Now I can go straight to 7500rpm, right? No. Not right. It should be gradual. Increasing engine speed a little at a time until you start using 7500rpm regularly. Same thing when you reach the next mark that “allows” you to go to redline.
OK, then why should I break in the engine gently? Because engine speed determines linear piston speed. And linear piston speed (together with combustion chamber pressure, among many other factors of course) determines ring temperature. Ring temperature is important because it will determine the changes in crystal structure in the ring material. Break the engine in too fast and the ring will harden too much and will be harsher on the cylinder walls filing away the finish in a shorter time. It is as simple as that.
Yeah, sure, but the guy on that web page says all this is bs. Well, to me is bs what he says. If you break in an engine faster, it will surely reach maximum power much sooner. BUT, peak power will be slightly lower and will last A LOT less. If I have to schedule a short engine test, I request a short break in protocol. If I have to test the durability of an engine component, I must request the longest break-in protocol available or the engine will not live through the long test. Race engines are broken-in fast because they need peak power NOW and the engine life will be MUCH shorter than a road engine anyway. Oh, and those pictures in the web page with a beautiful clean piston compared to an ugly dirty one… It’s just BS! You’ll never ever see a piston as clean as that one, coming from a engine that was running for more than a (very) short time.
Cheers to all!
kzmille
Registered User
Posts: 63
(5/28/03 7:56:52 am)
Reply         How should you break-in your engine.
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Engines broken in hard and fast run faster sooner. Engines broken in carefully and properly run faster longer! It just depends which result you're looking for.If you don't keep your bikes very long and you believe all the hype you'll get good results from running it hard. If on the other hand you plan to keep your beloved machine for many years, you will not regret breaking it in with gentle loving care. It just depends which result your looking for.
During the first several hundred miles new engines are sheding wear particles at an ever decreasing rate. One reason to limit RPM during the first 600 miles is to allow this material to be flushed out without doing any more damage than absolutely necessary. Do you really want your new engine turning 10,500 RPM when the largest of these chunks are floating in the thin film of oil between piston and cylinder, plain bearing and shaft, ball and roller bearing, cam lobe and follower?
The biggest myth in this whole controversy is that the rings will not seat if not run at high RPM. I have torn down engines with freshly bored cylinders and new pistons and rings after a two mile easy test ride and the rings were completely seated. Rings will seat as long as the cylinder is round and not tepered. Remember its the combustion preasure that pushes the rings against the cylinder. Opening the throttle is what raises this preasure not high RPM.
This "high RPM", "run it hard" technique comes directly from racing. It is often necessary to have a racing engine ready to race in a very short time period. Racing engines are also often built with larger piston and bearing clearances. Two stroke engines are vastly different in this area because with every intake, power, and exhaust cycle the wear particles are blown out the exhaust.
In the early seventies the S.A.E did a study to determine wheather the common practice of honing cylinders during " in frame " overhauls was beneficial or harmful. They formed two major conclusions. First; after honing, the only way to remove all of the honing debris is to wash the cylinders with plenty of hot soapy water. Not very practical with the crankshaft lying there. If not removed by this method very high initial wear resulted. Second; if the cylinder was within servicable limits, not honing resulted in no ring seating problems whatsoever! Remember its the combustion preasure that pushes the ring against the cylinder.
Since reading about this study in the late seventies I have rebuilt hundreds of car, diesel truck, and motorcycle engines without honing and have had no trouble with rings not seating. In fact, the only time I have ever heard of a ring seating problem in over thirty five years as a proffesional mechanic and machinist was in engines with cylinders that were very badly worn out of round.
RVZoo
Registered User
Posts: 129
(5/28/03 8:27:01 am)
Reply         Thanks
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Thank you KZ.
I think your post goes deeper than mine and teaches me a few things I didn't knew. I'm glad someone with your experience and knowledge agrees to some extent with me and is willing to share that knowledge. Cheers!
DolbyGuy
Registered User
Posts: 42
(5/28/03 1:25:46 pm)
Reply         What to do now???
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Brand new Mille, just about 230 miles on the od.
So, I've just started breaking in my new Mille according to the advice I received on this forum (and through the alleged "BS" web site) and ran the last 50 miles or so at higher revs, occasionally approaching 10.5k in 1st.
I'm not a racer, and I plan on keeping my Mille until they pry it from between my cold dead thighs.
What have I done? Have I #$%ed up my beautiful new Mille? Should I bathe it in warm soapy olive oil while singing the Godfather theme softly into the cylinders?
kzmille
Registered User
Posts: 66
(5/28/03 2:26:39 pm)
Reply         How should you break-in your engine.
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If what you have read above makes sense to you just reread the directions in your owners manual and get back on schedule. And as punishment extend your break-in 100 miles.
DolbyGuy
Registered User
Posts: 43
(5/28/03 2:50:19 pm)
Reply         Are there nasty beasties floating around in my engine now?
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I can't tell what makes sense and what doesn't, as I'm not a mechanical engineer but rather an electrical one.
Most of my gear-head pals agree with the "run it hard" school of thought, but then again they're into the racing thing while I'm just starting out in the SuperBike world.
I want my Mille to run forever, along with a few screaming track days put in there once I learn how to ride it properly.
Wahhhhh!! What do I do? Are there nasty bits floating around in my cylinders now just waiting to lodge somewhere where they'll do the most harm?
Not being an aggressive sort, should I follow the book and keep it down for the next 400 miles?
Is this "break-in controversy" difference a subtle thing that only the demanding rider would notice and then only at the extreme top end?
Should I not sweat it and just go back to the book on this?
Will 50 miles of high revs give me grief?
kzmille
Registered User
Posts: 68
(5/28/03 2:55:24 pm)
Reply         Are there nasty beasties floating around in my engine now?
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Don't worry about it! As I said above just get back on schedule.
DolbyGuy
Registered User
Posts: 44
(5/28/03 3:05:28 pm)
Reply         Back to the book
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Damn. It was fun while it lasted.
At least I've got an idea what it might feel like when I get past the 600 (now 650) mile mark.
What a $#%@$ awesome machine!
DeTuono_
Registered User
Posts: 141
(5/28/03 4:31:40 pm)
Reply         Paging RinOz!
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Thanks for one of the most useful posts I've ever read.
I think one of the reasons for the myth of short break in is that most people get their info from local experts, and most of these are racers. And as 'Zoo and 'Mille suggest, these guys aren't interested in longevity beyond the end of season tear down.
It takes the Internet to get access to the guys who actually DESIGN break in regimes, and WRITE the friggin' instructions in the Owner's Manual. Thanks again guys.
Nick
RVZoo
Registered User
Posts: 131
(5/28/03 4:35:23 pm)
Reply
        Re: Back to the book
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I agree with KZ. Back to the book and enjoy it. Those 50 miles shouldn't make a significant difference in the life of your engine. Have you changed your oil? It could be a good idea, even if you don't change the oil filter. Change the filter too if it makes you feel better.
As KZ suggest, I would extend the break-in period slightly and pamper the engine a little. Let it warm up properly. Avoid steady engine speed. Avoid higher temps (low speed in heavy traffic, for example).
But don't get "stiff". Ride it and enjoy it. When you reach the "marks" increase engine speed gradually.
Are break-in results perceivable? Yes, but that doesn't mean your engine is going to blow. All things being equal, your oil consumption may increase a little bit earlier. It may not. And anyway, earlier than what? Every engine will have oil consumption anyway sooner or later.
Above all, enjoy your bike and don't worry too much. Cheers.
rustie6
Registered User
Posts: 451
(5/28/03 7:35:43 pm)
Reply         Oh BOY....More Break-In!
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Guys, I knew that bringing up the “break-in” subject would be as dangerous as bring up the “which oil is better” subject......you’ll likely get as many answers as there are posts! I’m very surprised at some of the strange comments here, but also surprised at some of the excellent ones as well.
While it is totally true that cylinder pressure is what seats rings, that is NOT the case with pistons. It takes high RPM to scuff and polish all the high spots off so the "non-round" piston conforms as close as possible to the "round" cylinder, but what certainly DOES effect the piston is HEAT! This is not just idle “racers banter”, but from one of the all time experts of piston engines....Gordon Jennings (who just recently died unfortunately). He had performed VERY EXTENSIVE dyno testing in the area of break-in and found that all piston engines responded extremely favorably to the “High RPM, LOW Load” method of break-in. Remember, this is NOT High RPM, High Load.....which could be very bad for a new engine (although most still survive even this abuse). High RPM/Load is “generally” the way most racers break-in their engines....it is indeed a fast way to seat components, but is certainly NOT the correct method!
Although there are many spinning and reciprocating items in an engine to actually “break-in” or “seat”, the pistons and rings are THE MOST important ones. Second on the list are cams and followers, but if NOT properly lubed, these can actually be the first components to fail. Lets just assume that the cam and followers are indeed properly lubed (which is the case in most engines today anyway). The last items in importance to seat properly are the main and rod bearings (in a plain bearing engine). These items can indeed fail early as well, but that would be very unusual. Bearing components are easily kept within a very narrow production tolerance range during manufacture, and have the least amount of “seating” to acquire during break-in.
Also, plain bearings can take a lot of abuse from many small debris while still function perfectly. This is because the relatively soft bearing surface (compared to a hardened crank journal) is designed to literally ABDORB small contaminants. The great majority of ferrous (magnetic) “floaters” will be removed by the magnetic drain plug. The majority of non-ferrous floaters will be absorbed by the filter (that’s it’s job). If the engine is not “making” any major amount of metal, you do not need to worry too much about “floaters”.....unless there is some major internal failure (or the mfgr is a sloppy builder....which I have seen!). So, it is very natural to initially see some ferrous metal on the magnetic drain plug, and if you cut open the filter, you should see some non-ferrous aluminum bits....as well as some bearing bits. What IS very important is that on successive oil changes, these ferrous and non-ferrous contaminants DECREASE. If not, you may have a far more serious problem than the method in which you performed the break-in.
The method of “High RPM, Low Load” seats rings absolutely perfectly, specifically because the gas pressure is indeed elevated behind the rings, driving them into the cylinder wall with just enough force to **begin** the “polishing process”.....but certainly not with enough time and effort to cause a failure. If carried out as recommended in first gear only (in the beginning break-in process), the duration and amount of gas pressure (and cylinder pressure) is very limited in quantity and time.....just perfect for rings = ring face pressure with low heat and short duration.
This method also allows the piston to achieve high RPM with very little heat input....which is ALL the piston cares about (heat). Too much heat will cause the piston to expand and possibly seize in a new, or recently bored engine. If you maintain only low RPM during break-in, the highest rub points may not get the friction necessary to polish them away. This can extend the break-in much longer than necessary, with absolutely NO BENEFITS in engine life. High RPM alone will NOT damage a normal high tech piston. If you were not aware, high RPM failures are rarely caused DIRECTLY by the piston (unless a valve fails first), but are rather from the failure of a ROD. Rod failures occur the great majority of times when at TDC on “valve overlap”, where there is little load from compression to help reduce the rod’s “stretching load” (which is extremely massive at this point).
A rod RARELY fails at BDC (which most people think is the case). The rod is in “compression” at that point, where the its strength is actually the greatest. When at TDC on valve overlap, the rod is in “tension”, and is where its strength is actually the weakest. So...the key is simply to NOT EXCEED the RPM limit. Otherwise, using high RPM in low gears is definitely NOT a danger to the engine....it IS designed to run at that RPM (and is usually governed at that limit anyway).
Then why do the mfgr’s post only an RPM limit and not explain the above dyno proven facts??? Easily answered.....how many new vehicle owners do you think would really understand all this info (even most “bike oriented” individuals)? Not damn many, I’ll tell you!
It is far, far easier for a mfgr to write a short declarative statement, “do not exceed xRPM”. The only problem here is that IF one of these individuals does indeed intend to pass a “lumbering” someone or something by adding more throttle WITHOUT downshifting to prevent going over some contrived RPM limit, you will indeed be lugging your engine, possibly creating more heat than a new piston can withstand, and DEFINITELY increasing cylinder & ring face pressures FAR BEYOND what the same engine would experience if downshifted, allowing RPM to increase. What is KEY and not refutable, is “Load vs RPM”. If done properly, the engine will seat its numerous components earlier, with better results AND longer engine life.....NOT shorter!!! So, just remember: **High RPM, LOW Load**.......NOT High RPM HIGH Load.
As to the condition of the cylinder wall, it only stands to reason that we expect them to be clean and free from debris. Soap and water is indeed one of the best methods to clean newly honed cylinders with....but be prepared to spray a light oil (WD40) as soon as you dry them, or rust will begin almost instantly!
RVZoo
Registered User
Posts: 134
(5/29/03 5:49:42 am)
Reply
        Re: Oh BOY....More Break-In!
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Some things you say are correct Rustie, but you're not taking into account the changes in crystalline structure that high rpm (even at low loads) will cause in the compression rings material.
I am not a metallurgist, so I couldn't go into great depth there even if I wanted to, but I can assure you I HAVE TO request a gentle and long break-in procedure if I'm going to run a durability test. If I go for the higher rpm (still low load), shorter, break-in protocol (we also have that one, as well as other 4 or 5 for different ones for different applications), the engine WILL NOT last (about 99% of the times) for the complete length of the durability test.
Believe me, longer break-in = more money. We are very, very careful about money these days. If I could be using shorter break-in protocols I definitely would. But I would just not get the results I'm looking for.
Oh, and by the way, if I am going to test the maximum power a given engine will deliver, I HAVE TO ask for the long-gentle break-in protocol as well.
One last thing: these break-in protocols are revised every other year, just to make sure we don't use any unnecessary dyno-cell-hour. The suits are always worried that we engineers may be doing things too carefully.
Cheers!
DeTuono_
Registered User
Posts: 142
(5/29/03 6:12:18 am)
Reply         Jennings
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... was one of the good guys. I'm sorry to hear of his death.
From reading his book, I infer that he got his break in info from racebike builders, not roadbike builders. 'Zoo's info still seems valid.
Nick
rustie6
Registered User
Posts: 454
(5/29/03 12:42:26 pm)
Reply         More Break-in
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Zoo,
The "crystalline structure" you refer to is entirely dependent on the type of ring you are testing (including it's thickness and weight). I must assume that the type installed in your test engine is standard gray cast iron......which indeed IS fragile and can be seriously compromised, especially if ring flutter occurs from OVER revving.
The "High RPM, Low Load" concept certainly does not suggest RPM any higher than what the engine was originally designed to handle, so the crystalline structure point is fairly moot.....even a fragile gray cast iron standard ring assembly will not be damaged, changed or otherwise compromised if RPM limits are not exceeded. What you may be dealing with in your testing is very likely specific to the engine type/design in your facility. I don't doubt for one second that you have found specific parameters that benefit your subject engine, but to transfer those unique circumstances to a motorcycle engine with entirely different ring materials and ring designs does not change the beneficial effects of RPM vs Load.....as long as maximum RPM is not exceeded.
As you know, the metallurgical structures all throughout the engine are toughened by multiple heat cycles, so even the most fragile components become more resistant to wear and fracture as the engine is heated and cooled. Properly performed, the crystalline structure of the rings, and all the other components generally get better as the engine ages. So if the testing you are performing is continuous, that may be another reason for your low RPM requirement.
FWIW, Jennings wrote many SAE papers as well. His info and testing was derived over decades of testing just about every engine type and usage imaginable. He did not limit himself to just one area (racing), but I certainly suspect he had his favorites (as we all do).
So goes the controversy!!!!
rsv racing
Registered User
Posts: 69
(5/29/03 1:49:09 pm)
Reply         break in!
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Well, all of your posts sound convincing, and being a computer/electronics expert I can't argue with anyone. So I guess I got the best of both worlds in my break in.....Kept it under 6K for first 650 miles (might have gone over 2 or 3 times at most) but did run it hard during that time. After 650 miles, I got it up to redline (lower gears) but not all of the time, mostly I got it up higher in the RPM as I got comfortable with the bike. Oh well, Its all good.
rustie6
Registered User
Posts: 455
(5/29/03 7:49:54 pm)
Reply         More Break in!
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RSV (and others),
Actually, with the sophistication of todays engines, this break-in stuff is not all that extremely critical in the final "real world" analysis with a stock bike. It can be "important", but certainly NOT seriously "critical". These bikes RARELY run 100k miles anyway....if EVER!!!......
I doubt you could actually hurt one of these Rotax engines regardless of break-in method.....including what I feel would be fairly harsh one = High RPM, HIGH Load.
The current metallurgy, engineering design, assembly methods and machining tolerances of todays bikes are so heavily computer controlled, that nearly every engine produced (especially Rotax) is almost a "blueprinted" engine anyway.
Only MAJOR internal upgrades will make substantial HP changes = Big Bore, Cams and higher compression. Even some of these drastic measures result in only small incremental HP improvements. All the multi-angle valve jobs, porting (NOT polishing), even bigger T/B's will not make much differences until you make the engine breathe deeper = that Big Bore thing, and/or higher compression.....which would be absolutely a BLAST on a Tuono......and my next project
If you break your engine in with either the "High RPM, LOW Load" method.....or the "slow method", I seriously doubt that there would be any pratical differences you would feel with your "BD" (Butt Dyno). Even with a sophisticated inertia type dyno (Dynojet), you would likely see little differences there as well......until you make those "drastic" changes.
THEN.....aftermarket pistons, rings and cylinder bore finishing will become seriously affected by the break-in method because of the increased "variables" now entered into the mix. That's when the "High RPM, LOW Load" method will come in verrrry handy.....
RVZoo
Registered User
Posts: 135
(5/29/03 8:03:02 pm)
Reply
        Re: More Break in!
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I think that's a fairly good point Rustie. And I'll gladly give you the set so we'll stop making DolbyGuy paranoid.
Don't be DolbyGuy! Relax and enjoy your bike!
By the way, since the days I used to drive an Alfa Romeo 33 back in '92 I always said cars should be designed in Italy, but built in Germany. I guess the aprilia-Rotax marriage is something close enough to that... cheers to all.
kzmille
Registered User
Posts: 69
(5/30/03 7:23:03 am)
Reply         More Break in!
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If high RPM low load is the "way" why not do it standing still in neutral?
rsv racing
Registered User
Posts: 76
(5/30/03 8:30:28 am)
Reply         mileage
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Putting 1000 miles or more a week, I hope it will last me 100K miles, I hope.
Gunslinger70
Registered User
Posts: 116
(5/30/03 9:15:27 am)
Reply         Re: More Break in!
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Kzmille, It’s my understanding that that is exactly what happens at the factory after assembly, during the test run, on a partially serviced oil tank, which I gather heat cycles rather quickly. That being the case, I think Rustie is right on point in saying that our method of break-in is not overly critical especially since the most important run (the very first one) was done for you.
Just a couple of thoughts about RVZoo’s assertion that the 6000rpm limit is not corporate politics, it does make a certain amount of sense from a liability stand point IMHO. 6000 RPM’s doesn’t allow for crazy speed and any problems in assembly (chassis and otherwise) would likely show before 600 miles without (hopefully) killing someone or catastrophically destroying the equipment.
On a last note, thanx guys, great posts.
V/r,