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Usage of motoroil
On Thu, 17 Jul 2003 12:35:15 GMT, "Joe" wrote:
snip Again, I ask a simple question. If the rings, on a properly broken in engine seal well enough to keep molecularly small exhaust gases from getting INTO the crankcase, They don't "seal well enough to keep molecularly small exhaust gases from getting into the crankcase" . Where do you think crankcase pressure comes from? From GM: "If we could perfectly seal the combustion chamber between piston and cylinder wall, there would not be any appreciable cylinder block pressure. But, in fact, while piston rings attempt to do the job for us, in the best applications they can seal only about 95% or less of the pressure developed in the combustion chamber. This "blow-by", comprised mostly of unburned mixture of air and fuel, needs to be managed back into the intake stream for emissions purposes." http://service.gm.com/techlink/html_.../200103-en.pdf at a pressure of approx. 100 p.s.i., how in the HELL does something molecularly larger (oil) make it through the same rings at a third of the pressure? How? Very simple Asslicker, a piston goes down on the intake stroke, the combustion chamber is now under a vacuum. At this time the crankcase is ALWAYS under pressure. Couple this with oil rings that do not remove *all* of the oil from the cylinder wall, nor provide a 100% effective seal, and you get oil in the combustion chamber that will be burned/consumed once the power stroke comes along. Note that this isn't the *only* reason that oil gets past the rings but since you are stuck (once again) on pressure differential as your reasoning I thought I would post this (again). What's really going to blow his mind is the fact that oil is getting past the rings in one direction at the same time as combustion gas is getting past the rings in the other direction. Of course, the oil is burned shortly after it makes it's way past the upper ring, past the top of the piston and is exposed to the full heat of combustion in the cylinder. Steve |
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