page: Engine Tech: How To Break-in your High-Performance Street or Racing Engine written by Ben Alameda
If you have a High-Lift Camshaft, Start and bring the engine to Racing Temperature (160 degrees at least). Then let it cool down on its own and re-start the process again “half a dozen times or more”. If you have the patience to do this. The reason is for your “NEW” valve springs to be slowly “heat conditioned to its stressed environment”!
Once you have gone through your heat/cool cycle, Go out and slowly accelerate your engine to mid-RPMs and immediately let go of the gas and let it “Engine Brake” with out forcing it too much. Next go out to a faster speeds and let-off the gas and down-shift without forcing it from 4th to 3rd to 2nd and finally to 1st!
DO THIS ABOUT 6-12 TIMES AFTER YOUR HEAT CYCLING HAS BEEN DONE. AND IF YOU DO A “LEAK DOWN” CHECK – THE ENGINE RINGS WILL BE SEALED!
(This Engine ritual takes about 15 minutes and 4-8 miles)
2. from: mototuneusa.com
The Short Answer: Run it Hard !Why ??Nowadays, the piston ring seal is really what the break in process is all about. Contrary to popular belief, piston rings don't seal the combustion pressure by spring tension. Ring tension is necessary only to "scrape" the oil to prevent it from entering the combustion chamber.If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ...How can such a small amount of spring tension seal against thousands ofPSI (Pounds Per Square Inch) of combustion pressure ??Of course it can't.How Do Rings Seal Against Tremendous Combustion Pressure ??From the actual gas pressure itself !! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear intothe cylinder surface, to seal the combustion pressure as well as possible.
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