Datsun Roadster Forum-311s.org

any gearhead out there that agrees with this technique for proper engine break-in???

http://www.mototuneusa.com/break_in_secrets.htm

The guy looks happy with his results...

The hard facts everyone knows:

Wear is directly proportional to load and proportional to the cube of the speed of the mating surfaces. This means that a little increase in load gives a little increase in wear, a little increase in speed yields a big increase in wear. A big increase in speed yields a huge increase in wear...

How these fundamentals apply to break-in:

Break in is the process of "wearing" surfaces to the point that the wear is uniformly distributed. The "high" spots that are left from the fabrication process, be it machined, cast, whatever are worn down to the point that all of the high spots are gone.

My 2 cents:

Engineers that have studied these "phenomena" for a long time suggest low speed and load to break-in the parts of a newely fabricated device. The reasoning is simple and complex. The simple factor is that the particulate that is worn away is small enough not to do considerable damage when it finds a new home (most likely a cylinder wall or main bearing where you guessed it, it causes more wear). The second reason is on a metalurgical basis, if the stress in the region exceeds acceptable limits for the material, not only will it be worn away, but usually the heat treatment in that region will be lost and a larger chunk of material will come away with it. This means heavy galling and a wekened region of material. This will really show up in the main bearings that are intended to be a soft pillow for the crank. There will be long streaks of foreign and native material dug into them...

I see no reason why the wear-in process would stop if done in a gradual manner vs. beating an engine early. If his hypothesis was correct, engines would run forever without weraing out...

OK, maybe that was my 3 cents worth...TR