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Piston ring coatings and uses.

  
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Piston ring coatings and uses.

 
Pontiacman8 Pontiacman8
Moderator | Posts: 5770 | Joined: 02/08
Posted: 12/04/13
08:03 PM

chrome moly again.
Lets clear this up.
First there are rings with no coatings.
Although referred to as cast rings,most of the various ring materials including cast and ductile can be used without coatings to perform well.
For light duty grocery-getters that will see moderate use,little high speed and heavy load use, and which are not subject to heavy dust or high heat, these rings work just fine. Infact, these are used more then any other type of ring for low dollar rebuilds and low end crate engines.
The second type is the chrome ring.It has a cast,ductile or steel base and a chrome plated face.The chrome is extremely hard and is resistant to scuffing and scoring.
In addition,The hard faced ring will not easily pick up grit like a plain-faced ring and so is recommend for use in dusty condition such as gravel pits, dirt track, and dirt roads.Instead of catching and trapping grit that can score up and/or accelerate cylinder wear, the grit is scraped off and dumped in the oil were it can be filtered out. Once quite popular - before the perfection of better coatings - There are some disadvantages in terms of engine life, sealing characteristics,and temperature resistance the can crop up.
Finally there is the moly ring. NOT chrome moly.It is either chrome or moly, but never both.( The idea of chrome moly was probably the result of a racer's  appreciation of chrome moly alloy tubing - a hole nuther thing.)
A moly ring has had a groove cut into it's face which is filled with molybdenum.
One way this is done is to insert a pure moly wire into the groove with a spray flame process. A lot of passenger car rings are made this way.
The other way is plasma moly which are used in high performance race engines.
This involves spraying a durable moly compound using a plasma arc process into the groove to fill it and permanently bond it with the ring base material.  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races

Pontiacman8
Pontiacman8
Pontiacman8