As piston rings cycle back and forth in the cylinder, each cycle takes the piston ring through all three stages of lubrication. This cycling produces high levels of friction that rob horsepower from your engine. Fortunately, understanding how this occurs unlocks the secrets to reducing that friction, which, in-turn, unlocks hidden horsepower.
The tribologists at Total Seal use a tool called the Stribeck curve to engineer low friction piston rings. The Stribeck curve utilizes the formula Viscosity x Speed / Load to generate the lubricant film parameters. Thinking back to our water skiing analogy, the viscosity was the water. The speed was the velocity of the boat, and the load was the weight of the skier.
Following the logic of the Stribeck curve, as the piston nears top dead center on the compression stroke, the piston rings experience the highest load (from increased cylinder pressure) and lowest speed (as the piston comes to a stop). As a result, this is a source of high friction and higher wear.
As the piston begins to move down and accelerate (like the skier coming up from the water), both friction and wear decrease as the lubrication regime transitions from boundary to mixed-film and then to hydrodynamic.
Near mid-stroke the piston reaches maximum velocity (in some engines, this can be in excess of 100 feet per second). Due to those high speeds, friction begins to increase again as the lubrication parameter moves to the far-right end of the Stribeck curve. Taking all of this into consideration, Total Seal develops piston rings designed to overcome these frictional challenges.