Better explanation of how piston rings work...

[RPC Products <rpc-prod@windstorm.stormnet.com>]

Here is something to better explain whats going on with the piston
rings...

Mark


How Piston Rings Work
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Most people know that piston rings provide a seal for upper
cylinder gas pressure.  Have you ever thought about how the
relatively light ring spring tension (about 30 psi) keeps
the high gas pressures (about 750 psi max) from rushing past
the piston.

Rings don't seal just by their spring properties.  Gas
pressure above the ring forces it down against the bottom of
its groove in the piston.  The gas pressure also gets behind
the ring, in the back of its groove, and forces it out
against the cylinder wall.  Normally this works well.

However, when piston ring acceleration exceeds the gas
pressure holding it in place, the ring lifts upward in its
groove (piston nears top of stroke and is being slowed to a
halt at TDC).  As the ring lifts, gas pressure releases
above and behind the ring, causing the ring to hit up
against the top of its groove.  When the pressure behind the
ring is released, high temperature and pressure combustion
gases escape down the side of the cylinder wall causing
piston and ring overheating.  This hammering of the ring
groove and overheating shortens engine life.

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