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(Steven Shelikoff) wrote in message ...
On 23 Jul 2003 07:02:18 -0700, (basskisser) wrote:

(Steven Shelikoff) wrote in message
You should probably learn to read a little better. I said that the
pressure against the top of the rings is less than the pressure in the
cylinder. You've already stated that's impossible. But you were wrong
yet again. Now you're finally starting to understand why you were wrong
... maybe. We'll see.

Steve

Now, let me get this perfectly straight. You are saying

1. that the pressure on the TOP of the rings, due to compression is
LESS than the pressure in the rest of the cylinder?? heehe!!!

Uh, no. Please learn to read. I said that during the power stroke, the
pressure against the rings is less than the pressure in the rest of the
cylinder. However, it's also true that the pressure against the top of
the rings is less than the pressure in the rest of the cylinder during
the compression stroke. This is due to the fact that the rings don't
produce a 100% seal and let some of the compressed mixture by them and
that escaping gas has to pass through the thin turbulent gap between the
piston and the cylinder.

Whoa here, won't that layer of viscous oil on the cylinder wall (the
one you claim is there getting burned) create a seal? It MUST, if as
you've stated, it is viscous enough to cause a pressure at the rings
of "several times" the compression of the engine.

But the difference isn't nearly as great as
during the power stroke. You can laugh all you want. It only shows
your ignorance.

No, it shows YOUR stupidity.

2. But, on the same hand, magically, the pressure on the bottom of the
ring is GREATER than the pressure in the rest of the crankcase?????

Exactly. Because the ring is moving down and pushing oil out of the way
as it does so. When it's moving back up, that's not the case anymore.

3. The pressure on the bottom of the rings is "many times greater"
than the 100 or so psi of the combustion chamber? How much? is it 1000
psi? 1,000,000 psi????

Why don't you figure it out for yourself. I've already posted
everything an engineer needs to do so. But I'll tell you what I will
do, I'll give you some feel for how much force is against the rings *if*
the oil being wiped away is at a peak pressure of 1000 psi.

HOW IN THE HELL does the oil get to anywhere NEAR "a peak pressure of
1000 psi??

Say the
cylinder it 3" in diameter and the gap between the piston and cylinder
is 0.005". Also, assume that the gap is totally filled with oil, which
really isn't the case but it is a max case possible force. The area is
3*pi*0.005=0.047 sq in. At a peak pressure 1000 psi, the oil exerting a
max case force of 47lbs against the rings as they are trying to wipe it
away at a very high speed, the top speed of the piston as it moves down
the cylinder.

In actuality, the film of oil that the rings are pushing aside is really
much less than 0.005". Some studies have shown that to prevent
excessive wear, you want an oil film thickness of at least 5 microns.
So we'll use 5 microns as a "min case", or minimum force that the oil
might exert against the rings. 5 microns is about 0.0001975 inches. So
the area in this case is 3*pi*0.0001975=0.00186 sq in. So in this min
case, 1000 psi of peak oil pressure exerts about 1.86 lbs of force
against the rings as they move at their highest speed down the cylinder.

In reality, the oil film thickness that the rings would be trying to
push away would be somewhere between the max of 0.005 and the min of
0.0002. So at 1000 psi peak pressure against the bottom of the ring,
the force would be somewhere between around 2 lbs and 47 lbs. That's
certainly within the realm of possibilities, so 1000 psi is also within
the realm of possibilities.

However, like I said, you have everything you need to figure it out.
You can figure out a representative peak piston speed knowing the stroke
and rpm of a sample engine. You can figure out the pressure/force that
oil of a certain viscosity would exert against something pushing it at
that speed. Give it a go. Let's see just how good a structural
engineer you really are, as this should be right up your ally. I'll bet
you come up with a number that is much greater than 100 psi.

Will you bet that, as you've stated prior that I'll come up with a
number that is "many times" greater than 100 psi? Or are you changing
your story to just now say "much greater"? There is a huge difference
here.

Steve