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    Producing Quality Computer Tools for Racers and Engine Builders since 1986

 

 

 

 

 

Piston Rings

What is a Piston Ring?

 

Piston Rings
Piston Rings - Image courtesy of diytrade.com
A Piston Ring is a thin circular ring that fits into a small groove in a piston. Because there is a gap between the piston and cylinder wall you need something to stop the combustion force from flowing in between the gap of the piston and cylinder wall. That is where the Piston Ring(s) come into play.

The Piston Ring increases the efficiency of the combustion by greatly reducing the Blow By. The less Blow By the more combustion pressure available to push on the piston to produce power.  Also, blowby can remove oil film from the cylinder wall, increasing friction and wear.

A great deal of design work has gone into minor details about piston rings, especially the shape of the outside face which rubs on the cylinder wall.  A well designed ring pack will contain combustion gases very well, help keep oil from entering the combustion chamber, AND keep friction low.  

Piston Ring Friction:  Piston ring friction contributes significantly to overall engine friction, so any reduction in ring friction can greatly improve engine power.  Sometimes race motors will give up oil control for lower friction.  Low friction rings are typically thinner and have less tension pushing them out onto the cylinder wall.  Also, the fewer number of rings, the lower the friction.  A low speed diesel could use 4 or 5 piston rings, where a race motor may try to get by with just 1.

 

Oil Ring

 

Oil Ring
Oil Ring - Image courtesy of advrider.com
The Oil Ring (for 4 stroke engines only) is the bottom ring. Instead of containing the combustion to the top of the piston, the Oil Ring collects, holds and distributes oil to the cylinder wall. At the bottom of the piston stroke the Oil Ring collects oil from the engine and holds it in the cup like areas of the ring and this allows it to distribute oil on the way up to the compression or exhaust strokes.

 

Programs that take Piston Rings into account

We have 3 programs that work with Piston Rings when conducting Engine Simulation: Engine Analyzer v3.4, Engine Analyzer Plus v3.4 and Engine Analyzer Pro v3.9.

And we have 2 other programs that take the Piston Rings into account when making calculations. Compression Ratio Calculator v2.3. And Engine Build Log Book v1.1 will document the Piston Rings used for future reference.




 

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