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(Steven Shelikoff) wrote in message
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, 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?

Because the pressure of the oil against the rings as they are moving
down the cylinder wall is many times greater than 100 psi. And because
oil molecules tend to stick together in a thin film. That's one of the
properties that makes oil a good lubricant. What will really blow your
mind when you think of it is that oil can get past the rings on the
power stroke, where the pressure in the cylinder is much greater than
100 psi. However, the pressure against the rings from the top is
nowhere near as high as the pressure in the cylinder due to the tight
clearance between the piston and the cylinder. If the rings had to face
the full pressure of the combustion gasses in the cylinder (as the would
if there was a lot of space between the piston and cylinder) they could
never do their job of keeping combustion gasses out of the crankcase.
As it is, they only have to seal against the small amount of gasses that
make it between the piston and the cylinder.

Steve

Okay, here we go. You are now claiming that the pressure in the
crankcase, at the time that a piston is moving down the cylinder, is
"many times greater than 100 p.s.i.????? Are you just plain flipping
NUTS? Let's say it's an eight cylinder motor, okay? Using YOUR
analogy, then, with eight cylinders, there is almost always a cylinder
moving "down". SO, just how many times 100 psi should my oil pressure
gauge show? Should it be 500 psi? 600psi? Now, because it is
essentially ONE vessel ie: the crankcase, there can not be a
differential in pressure, so don't even try it. That would be akin to
saying that the pressure is different in one side of an air compressor
tank than it is in the other side. NOT.

Now, there is the EXACT same amount of pressure of the gasses on the
rings, in pounds per square inch, as there is on the top of the
piston. VERY simple physics.