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Piston ring break in

Guys, what the general concensus for breaking in new piston rings on freshly honed cast iron cylinders?(original pistons). Fast up and down? or slow and easy?
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Old 07-27-2005, 08:54 PM
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Run it hard. On boost and on vaccum. You need the pressures to seal the rings against the ring grooves and the rings against the cylinders.
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Old 07-27-2005, 09:07 PM
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That's the consensus of what I've read also. In addition going back and forth (full load and backing down) pushes oil behind the rings in both directions to clean out all the particles being generated, in that area, from the ring and cylinder material.
-h
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Old 07-28-2005, 06:34 AM
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AS above with heat cycling.
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Old 07-28-2005, 06:51 AM
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I break them in by running them hard (below 5K for first 1k mi), and that includes deceleration/down shifting. And heat cycling is also important. This method works well for me, as the rings seat promptly.


Good luck.

Regards,
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Old 07-28-2005, 08:49 AM
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All you have to worry about is over temp. If the temp is normal or below, run the heck out of it. But if the temp goes up , back off untill it goes down.
Old 07-28-2005, 08:12 PM
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When you say heat cycling you mean taking the engine from normal RUNNING temp up and down and not actually shutting it down to cool Correct?
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Old 07-28-2005, 08:40 PM
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I don't think so. NEVER run your engine at higher than normal temps.

All the preceeding info on breakin is basically correct. By heat cycling I beleive they mean a cold engine, running to normal temp, and shutting down to get back to cold. I have not read anywhere where temp cycling is beneficial, its usually what wears things out. An engine is designed to run at a single temp. The closer you can keep the engine to that temp the better. All new cars hold temp very well and consequently are able to make a lot of power and still meet pollution reqs.

Ring break in is dependant on proper machine operations during rebuild. If done correctly the rings will be broken in within a few minutes and only one or two full throttle accelerations and decellerations will be required to finish the job. Common rebuilds do NOT utilize the proper steps to machine the cylinders so that the rings will break in this quickly, so you still do the same thing but several times and you must keep an eye on the temps so that they do not go higher than normal. If the temp does creep up, back off, let it cool. Some of the worst done rebuilds may require up to 12,000 miles for the oil consumption to stabilize (the rings are broken in at that point), but a proper job will have them broken in before you get the car home for the first time.

What are the proper machine steps? Final honing is the critical last steps. The surface finish must be within mfg specs, which for newer cars in on the order of 5 micro inches. In addition a step called plateau honing is required. A special hone is required for this step, which removes sharp peaks from the cylinder wall finish and proivides proper oil retention on the cylinder walls. These steps must also be done while using a torque plate to compensate for cylinder distortion due to the head bolts, and for the really anal types it must be done at operating temp of the engine.

Another assumption is that truly modern ring designs are used. Modern rings are ready to go, ie they have been machined to perfact circles and in theory do not need breaking in. Many euro rings are made using 200 year old technology so sometimes you just cannot get what you want. Euro talk is big but their tech lags somewhat. Mahle is a good company with current products. Most of the others may be somewhat out of date.

Last edited by snowman; 07-29-2005 at 07:00 PM..
Old 07-29-2005, 06:46 PM
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The three things going on per what I've read:
1. don't over heat the rings during the break in process, this is mentioned above.
2. breaking in the engine easy and slow can allow glaze to form, then the rings may take much longer to seal and in the mean time all the leakage does a number of bad things
3. rings are pushed against the cylinder wall because of the combustion pressure, that's why you run close to or at WOT and back down.

So I guess it is sort of balancing act, don't over heat, don't let glaze form and keep pushing the rings hard against the cylinder wall.

There are quite a few websites that talk about this controversial subject.

As Jack mentioned rings should seal very quick if all the proper machine steps are done. I think the factory has the resources to do the processes properly and keep things calibrated and maintained. I have very little confidence that any 3rd party aftermarket company can provide this as a reliable service. I could be wrong. I think this is the primary reason to follow some sort of break in "process".
-h
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Old 07-29-2005, 08:45 PM
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Heat cycling as in Waynes book. Initial run to temp for 10-15 min then shut down and allow to completely cool off. Repeat with progressively longer run times.
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Old 07-30-2005, 06:46 AM
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Hi,

If you are have a complete rebuild including cams then the first 20 minutes is meant to be at a constant rpm to allow the cam to bed in. If the rings bed in within a short time........how does the initial 20 minutes effect the rings?

Cheers

Mark......
Old 07-31-2005, 08:38 PM
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Correction on first 20 minutes. It is NOT at a constant rpm. The RPM should be constantly varied to prevent any abnormal wear patterns and to insure everything is lubed properly. The first 20 minutes breaks in the cam and in a properly machined engine a lot of the rings. The first wot finishes it off. On a race engine this is usually done on the dyno so when it goes into the car its GO time.
Old 08-08-2005, 06:15 PM
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Jack, If you are correct .... see if Wayne can list a correction. My understanding is that the first 20 was constant rpm and was constant because 2k rpm produced the smallest forces on the cam lobes.
-h
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Old 08-09-2005, 04:21 AM
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Hi,

Are there two trains of though here a conflict or a process misunderstanding?

If the rings need varied rpm and the cams constant rpm (20mins) what is the correct approach when both are new?

Cheers

Mark.....
Old 08-09-2005, 04:42 PM
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As far as ALL the engine books say is varied rpm for the first 20 minutes. Don't know of any exceptions to this. Min rpm is 2000. Main purpose is to insure sufficient oiling to the cam. At any ONE rpm the oiling may not be sufficient, consequently, the rpm is varied.

Last edited by snowman; 08-09-2005 at 06:58 PM..
Old 08-09-2005, 06:56 PM
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Jack,
That makes sense.....I can't imagine that say 1800 rpm or 2200 rpm is bad for the cam lob/bearing break in. Varying would allow different pressures and spray variations in case 2000 rpm +/-50 didn't provide some needed variation. I guess at this point I would be comfortable with 1800-2000 or 2000-2400rpm and vary back and forth fairly quickly for the first 20. I also guess that the cam bearings won't have an issue on my 89 as it seems the journals are big and lobe sets are supported on both sides. Just my 2 cents. BTw - what engine book would you recommend besides Wayne's?
-h
-h
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Old 08-09-2005, 09:01 PM
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Here's some interesting break-in info:
http://www.mototuneusa.com/break_in_secrets.htm
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Old 08-09-2005, 11:50 PM
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Yes....I have read that a couple of times. Seems like a lot of good information and I think generally follows the Wayne method. It is interesting to note that there are very few outside references.
-h
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Old 08-10-2005, 06:07 AM
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