I started with a Road Rage post in another thread:

[QUOTE]Originally posted by Road Rage

 

My head hurts now...

 

dude, you lost me at tribolgist....

 

Jeez, only one fledgling tribologist? - what do they teach in schools these days - recycling, dinosaurs, and Global Economy conspiracies?

Jankemi:

You are on to it, and there is a lot lost in the transation, I agree. Tribomutation.

Let's look at the dynamic forces at play here. Other than the cylinder bore, the main mechanical component is what? - that's right, the two upper rings, and the oil control rings. And the third element is the cylinder bore - its inherent trueness, its porosity, and the uniformity of its casting are in play. The fourth element is the uniformity if the crank and rod, and how tight their tolerances are as they reach the top of the stroke, and "wiggle". The 5th element is that hottie from the movie with Bruce Willis.

In the old days of Dad's Oldsmobile, the castings were sloppy, the rings very tight, and the cast iron not very "fine" in grain. So the tribomutaton layer would be very thick, with plenty of "smooshing" as you call it - great name. This explained why some cars ran for 200k miles, and some were "Smokey Joes" at 60 k - it was a crap shoot.

Today, ring lands are much lower in pressure, and the blocks and/or cylinder liners are much better castings, and more uniformly machined. The tribomutation layer is smaller, and breakin more uniform - hence the likelihood of yu and I purchasing two Accords on the same day, driving for 5 years, meeting over a beer, and having similar stories of glory and delight are much more likely.

I think one can make a case for the gradual breakin guidelines - break in hard with high rpms, and the resurfacing is likely to be non-linear, until the design tolerances of the various components is realized. Sort of like the smooth brushstrokes of Vermeer vs. Van Gogh's "attack" of the canvas with his oils. And I would not rule out the chemical oxidative possibilities of too much heat too soon in the "smoosh" lifecycle. You might get power quickly, but perhaps risk that the accumulated smoosh material might glob up enough to pull a ring enugh o pit or slightly bend it. Imagine taking a large aluminum snowshovel and pushing it with consistent force down a sidewalk, compared to runnin with it - which produces te better result?

Now, it would be very interesting to get the author's opinions about what the carbon fiber material does in our engines - I would speculate that similar forces are at work, but would not rule out that the combo of hydrogenated chemical action at the surface might react with the carbon to form a particularly uniform, smooth, and hard surface - just what you would need to sustain high rpm use, and provide longevity. Combine that with the precision machining, and all the other S2K goodies and you get what we get - sewing machine engines that last forever.

 

Presumably the presence of carbon in the tribomutation layer in iron cylinders is a result of the lubricant molecues breaking down somehow. I can't see how the iron cylinder would have enough carbon in it to form a layer of near 100% carbon. It is also interesting that they ignore the normal surface roughness that we associate with honing or machining. That roughness is 1000x or so the thickness of the tribomutation layer, yet apparently has little influence on wear.

If the tribomutation layer thicknes is determined at break in, then break in lubrication is of utmost importance, assuming of course that lubricant somehow influences the layers' formation. The 15 hours that they estimate for layer formation corresponds roughly to the 600 miles generally used for engine break in.

The plasticity of the tribomutation is also interesting. They treat the carbon/iron oxide layer as a liquid with a viscosity & flow.

Also - the nanometer scale implies that the tribomutation layer (10-70nm) is only a few molecues thick (approx .2nm for an iron atom) and that quantum-electrodynamics must play a role. Also - it seems like the lubricant molecues would be quit large in relation to the sizes here.

Well - I'm still going to follow the owners manual & break it in softly.

--Mike

 

Mike, how does this relate to our non iron cylinders?

 

It probably doesn't . The properties of silicon might be much more relavent. I'm not sure that I've ever read the composition of the S2000 linings - I remember a big ceramic debate a while back but don't recall that the actual material was determined.

FRM (Fiber-Reinforced Metal) doesn't tell us what the fibers are made of. Could be horsehair for alI know.



--Mike

 

Interesting discussion gentlemen - thanks!

 

one of the fringe benefits of owning an S2k is the depth and breadth of knowledge that owners can tap into on this site. (and even non-owners, but it's more fun to be the former )

thank you!

 

[QUOTE]Originally posted by jankemi
It probably doesn't . The properties of silicon might be much more relavent.