BoatBanter.com - View Single Post

On 16 Jul 2003 11:21:50 -0700, (basskisser) wrote:

(Steven Shelikoff) wrote in message

--------------------------------------------------------------------------------

Whenever an engine's piston rings are replaced whether in part or in
entirety it is necessary to break in the engine. Piston rings are
replaced at a complete engine overhaul or repair, top overhaul or
single cylinder overhaul or repair.

When we refer to engine or cylinder break in, we are talking about the
physical mating of the engine's piston rings to it's corresponding
cylinder wall. That is, we want to physically wear the new piston
rings into the cylinder wall until a compatible seal between the two
is achieved.

Proper engine break in will produce an engine that achieves maximum
power output with the least amount of oil consumption due to the fact

Notice it said LEAST amount, not none.

Notice it said consumption. Did you notice?

Of course. Is that why you posted this? Because you saw the word
consumption? What a simple minded fool you are.

Okay, NOW we're getting somewhere. Please try to follow. DO you still
contend that consumption and burned mean the same thing? Yes or no.

I contend that for the purposes of this discussion, burned is a subset
of consumption. I further contend that when the GM reference says that
the oil on the cylinder wall is consumed in the combustion process
during the power stroke, that IS the exact same thing as saying it is
burned. I further contend that when YOUR reference says "This oil is
burned each and every time the cylinder fires" when it's talking about
oil that gets past the rings, that oil is also burned.

So now we're getting somewhere. Please try to follow. DO you still
contend that NONE of the thin film of oil that's on the cylinder wall
and consumed in the combustion process during the power stroke is
burned? Yes or no.

that the piston rings have seated properly to the cylinder wall. When
the piston rings are broken in or seated, they do not allow combustion
gases to escape the combustion chamber past the piston rings into the
crankcase section of the engine. This lack of "blow-by" keeps your
engine running cleaner and cooler by preventing hot combustion gases
and by-products from entering the crankcase section of the engine.
Excessive "blow-by" will cause the crankcase section of the engine to
become pressurized and contaminated with combustion gases, which in
turn will force normal oil vapors out of the engine's breather,
causing the engine to consume excessive amounts of oil. In addition to
sealing combustion gases in the combustion chamber, piston rings must
also manage the amount of oil present on the cylinder walls for
lubrication. If the rings do not seat properly, they cannot perform

Notice it said that the job of the rings is to manage the amount of oil
present on the cylinder walls for lubrication, not wipe all the oil away
as you have said.

Where does it say that? I can't find ANYWHERE where it says "the job
of the rings is to manage the amount of oil present on the cylinder
walls for lubrication, not wipe all the oil away". Now, would you say
that if you had enough of a seal to "seal combustion gases in the
combustion chamber", that oil would get past that seal? Absolutely
NOT.

Your stupidity is now approaching the point of absurdity. You can't
even read what you posted. And now, I quote directly from it only a few
sentences above the quote and you say you can't find it? Here is the
direct quote from YOUR cite:

"In addition to sealing combustion gases in the combustion chamber,
piston rings must also manage the amount of oil present on the cylinder
walls for lubrication"

HOW IN THE HELL can you read that, and then conclude, that the rings
leave oil to be burned? It says......M A N A G E, get it? That means
in a sense to keep it at a minimum, or not at all. NOW, you stated

Yes, it says manage it. Which means to keep it at a minimum. It
further says that the oil must be there for lubrication. So "manage"
cannot mean "not at all" or there would be no required oil for
lubrication.

above that the post said "the job of the rings is to manage the amount
of oil present on the cylinder
walls for lubrication, not wipe all the oil away". It does not, in
fact say that. You've added the "not wipe all the oil away". YOU said
that. The cite did not.

You're such a stupid moron that you don't even know when I'm quoting
your reference and when I'm not. I'll give you a hint: If I say I'm
quoting it or if I put quotes around it, then I'm quoting it.
Otherwise, I'm not. You'll find neither is the case when I said "not
wipe all the oil away." That is what YOU say the rings do, i.e.., they
wipe ALL the oil away so none is left on the cylinder walls. Am I
stating your position correctly, that you believe ALL of the oil is
wiped away from the cylinder by the rings on their way down? If that is
your position, it disagrees with your cite which says AND I QUOTE: "In
addition to sealing combustion gases in the combustion chamber, piston
rings must also manage the amount of oil present on the cylinder walls
for lubrication". I.e., the cite is saying there must be some oil
present on the cylinder walls for lubrication and one of the jobs of the
rings is to manage that amount and prevent excessive oil on the cylinder
walls.

this function and will allow excessive amounts of oil to accumulate on
the cylinder wall surfaces. This oil is burned each and every time the
cylinder fires. The burning of this oil, coupled with "blow-by"
induced engine breathing, are reasons that an engine that hasn't been
broken in will consume more than its share of oil.

Notice that it says if it burns excessive amounts of oil, it's
*consuming* more than it's share of oil, not that consuming no oil is
the normal case. The normal case is consuming it's share of oil, by
burning the non-excessive oil from the cylinder wall surfaces.

Again, consumption. Read it please.

Yes, it says the engine will consume more than it's share of oil by
BURNING it, both from the cylinder walls and from "blow-by" that gets
reintroduced to the combustion chamber through the breather. Do you not
see that? Sheesh.

When a cylinder is overhauled or repaired the surface of it's walls
are honed with abrasive stones to produce a rough surface that will
help wear the piston rings in. This roughing up of the surface is
known as "cross-hatching". A cylinder wall that has been properly
"cross hatched" has a series of minute peaks and valleys cut into its
surface. The face or portion of the piston ring that interfaces with
the cross hatched cylinder wall is tapered to allow only a small
portion of the ring to contact the honed cylinder wall. When the
engine is operated, the tapered portion of the face of the piston ring
rubs against the coarse surface of the cylinder wall causing wear on
both objects. At the point where the top of the peaks produced by the
honing operation become smooth and the tapered portion of the piston
ring wears flat break in has occurred.

When the engine is operating, a force known as Break Mean Effective
Pressure or B.M.E.P is generated within the combustion chamber.
B.M.E.P. is the resultant force produced from the controlled burning
of the fuel air mixture that the engine runs on. The higher the power
setting the engine is running at, the higher the B.M.E.P. is and
conversely as the power setting is lowered the B.M.E.P. becomes less.

B.M.E.P is an important part of the break in process. When the engine
is running, B.M.E.P. is present in the cylinder behind the piston
rings and it's force pushes the piston ring outward against the coarse
honed cylinder wall. The higher the B.M.E.P, the harder the piston
ring is pushed against the wall. The surface temperature at the piston
ring face and cylinder wall interface will be greater with high
B.M.E.P. than with low B.M.E.P. This is because we are pushing the
ring harder against the rough cylinder wall surface causing high
amounts of friction and thus heat. The primary deterrent of break in
is this heat. Allowing to much heat to build up at the ring to
cylinder wall interface will cause the lubricating oil that is present
to break down and glaze the cylinder wall surface. This glaze will

Apparently there must be oil present on the cylinder wall even on a new
engine being broken in.

That's the reason for break in....jeez!

You think oil present on the cylinder wall of a new engine is the reason
for breakin? Wow, are you confused.

Oh, my god, you are WAY beyond stupid!!!! What an ignorant statement.
You have JUST shown in one statement how much you DON'T know about
engines. The reason for break in, which is clearly stated in the post,
is to make an adequate seal betweeen the rings and cylinder wall. Did
the B.M.E.P. even hit that pea brain of yours? Apparently not. Again,
please tell me, if the rings can seal well enough to keep gases out of
the crankcase, which are sometimes in the area of 100 p.s.i., and
molecularly much smaller than oil, how can the oil, with larger
molecules, and under less pressure, make there way INTO the chamber?
Let's see, gases, mostly air, can't get past the rings under 100
p.s.i. but oil, at about 35 p.s.i. can....interesting.

Is THAT the problem you're having? Visualizing how oil can get past the
rings during the power stroke as the piston is going down? I'll give
you a hint: the pressure of the oil against the rings as they are moving
down the cylinder at a high rate of speed during the power stroke is
MUCH greater than 35 psi. I'll give you another hint: the pressure
inside the cylinder is not constant everywhere. Just where do you think
some of the low spots in the pressure is? Hint: it's near the upper
side of the rings. I'll give you another hint: because oil is a viscous
fluid and also because it is designed to create a thin film that on a
molecular level resists being broken, there is more at work here than
just the simple pressure difference between the oil below the ring and
the gases above the ring.

I'll leave it to you to figure out how much higher than 35 psi the oil
pressure on the bottom side of the rings is. Knowing the viscosity of
the oil, the speed of the piston and the pressure of the ring against
the cylinder wall, you should be able to figure it out for yourself.
You should also be able to figure out for yourself how much lower the
pressure at the upper side of the top ring is than say, at the top
surface of the piston by using some typical values for the clearance
between the piston and the cylinder and typical values for how much
below the top of the piston the upper ring is. Let's see just how good
at math you really are. You claim to be an engineering math whiz.
Prove it.

All I can say is WOW. You must not have even read your own cite if you
can't even find the parts I quoted from it.

Again, show me where it says that the job of the rings is "not to wipe
all the oil away". Where IS that? Your getting so good a spinning, you
should go help your president.

Where it says, and I quote, "In addition to sealing combustion gases in
the combustion chamber, piston rings must also manage the amount of oil
present on the cylinder walls for lubrication"

If the rings wiped *all* of the oil away as you assert, there would be
*none* on the cylinder walls for lubrication. That goes against what
your cite says the job of the rings is.

Steve