Spark ignited engine brake-in procedure

[ebola]

Its quite interesting, that many perfomance engine builders do not agree on engine break-up procedure.There are opinion, that for perfomance break-in engine has to be rewed right after warm-up and have to be loaded hardly, and has to be used with mineral oil only.With best efforts to understand this theory, I cant realise a superiority of mineral oils, and also high load break-in procedure against ordinary easy break-in.What experienced engineers think about that? Maybe there are some resourses on the net to read? Some proper research?
Thanks
Andrius

 

[Rob45]

You might want to consult a dictionary before your next posting, but as I understand your question(s), you are asking about whether to use mineral (vs. synthetic?) oil for new engine break-in, and what a good break-in procedure should be?

First, I'd strongly recommend following whatever break-in procedure a manufacturer specifies, and these procedures can vary somewhat since different manufacturers build engines to different tolerances.
The object of engine break-in is to get various parts, especially piston rings and cylinder walls, seated to each other without scuffing or other damage.
This is best done by avoiding high-heat and high load conditions for a period of time; the length of this period of time will depend on the accuracy of the original machining and the fit of the parts.

My own experience suggests that a sizable number (say 40 - 50 times) of brief periods (2 - 4 seconds) of acceleration in a lower gear up through 2/3 - 3/4 of the maximum engine rpm will give a good break-in. I've run literally thousands of vehicle pass-by noise tests, and a number of the test vehicles I've used uniformly had excellent performance and no oil-consumption for many years thereafter. Other points to consider are that the break-in should only be done on a warm engine, and that prolonged periods of constant-speed operation should be avoided.

Regarding mineral vs synthetic oils: there's no reason I can think of not to use a synthetic oil for break-in. Many high-performance vehicles are shipped this way.
Unless the engine was so poorly-made that the manufacturer is counting on the poorer lubricity of mineral oil to allow scuffing and wear to remove the "high-spots" in the bearing surfaces!

 

[patprimmer]

As is mostly the case, I pretty much agree with Rod.

Synthetic oil does a fine job for break in, but it is more expensive than mineral oil. I like to change oil very quickly on a new engine so as to flush foreign bodies and the by products of break in from the engine, so the long life aspect of synthetic oil is wasted.

Break in procedures are influenced by many variables. A modern well prepared race engine with roller cam can be broken in in a few minutes after a fast idle warm up, with a few very short full throttle bursts and fast idle rest periods.

Fast idle keeps oil circulation up and aids warm up.

Short power bursts bed the rings.

Fast idle rest periods allow the wear surfaces to cool off and thereby avoid scuffing.

It depends mainly on camshaft and follower type, bore finish and bore clearance.



Regards

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