Quote:
Originally Posted by yupetc
On SAPS you'll get degradation to the catalysts only if you're experiencing excessive oil loss through combustion into the exhaust. This can stem from worn piston rings which gets you high amount of blow-by into the PCV ducting, back to intake, into combustion, into exhaust, etc. You'll also get excessive oil loss through worn piston rings or compromised cylinder walls where oil gets lubed onto the cylinder walls, then piston rings do a bad job at scrapping the oil back down, letting that oil get through combustion then the exhaust. If I remember correctly, it's the sulfuric components after combustion of oil that gets the catalysts all gunked up, I am not a chemist, so correct me if you discovered else chemicals doing this harm. But whatever it'd be, it's the oil passing through that'll work against the catalyst; and that's why in my earlier post I refer to how a car driver need to know the health of their engine and oil loss characteristics to consider using full SAPS. Nowadays the bearing gaps and piston-cylinder wall clearances are on a much tighter tolerance for emissions and efficiency, you'll almost have no issues running full saps unless you're riding on a oil-leaky motor (internally). Our N55's when the valvecover is working well, has a good PCV oil catcher. And our factory spec'd piston-wall clearance and ring gaps are pretty tight. Like I was saying, if you're not losing oil just from operating the engine, I think you can run full SAPS without much worrying.
On your 3rd pic, it still doesn't reveal much semblance to misfire events, at least not [...]
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Thanks I really Appreceite you input! This was my first rod bearing install on a BMW and I have been trying to piece together the knowledge to understand what the wear was -that explanation makes total sense!
It looks like I might be adding a 2nd N55 2011 e91 335i so no doubt will be upto the same again soon
