Piston and Piston Rings: The Power and Efficiency

Piston piston rings are cylindrical engine components that are designed to take the load of engine combustion. Pistons are often referred to as the heart of an engine. Just like a heart pistons have different sections and components that help facilitate its job. 

Piston rings are the components of a piston that specifically help the piston properly bear the load of combustion while keeping the other components well-lubricated for the most efficient cycle. 

In an engine, pistons and piston rings play a major role in power and efficiency. They are one of the main reasons your engine produces power and burns more or less fuel. Damaged pistons or piston rings will cause you to see a drop in your vehicle’s power and efficiency. Let me give you a more detailed understanding of how these components do such a thing.

What you will learn about :

Pistons 

As I mentioned in the beginning pistons are engine components that are made to take the load of combustion. Pistons are usually made from high-temperature aluminum-silicon alloys. This material has great thermal conductivity properties for an application like this. Pistons are located in the cylinder of an engine block, where they move up and downward during the combustion process. Located above the piston is the combustion chamber where combustion takes place. Located below the piston are the connecting rods, crankshafts, and oil sumps which help facilitate turning the energy from combustion to mechanical power.

The Pistons are connected to the top or small end of a connecting rod via a piston pin. The connecting rod is connected to the crankshaft on the other end in the crankcase area of the engine. Once combustion happens the piston is the main peace that receives the load of the mini explosion pushing it downward. The connecting road which is connected to both the piston and the crankshaft is the main peace that transfers that energy from the piston to the crankshaft. 

For optimal engine power and efficiency, the combustion gases cannot pass around the piston into the crankcase. This is where the piston rings come in. The piston rings prevent this from happening by sealing the combustion chamber for proper intake, compression, power, and exhaust strokes.

Piston rings 

Pistons are designed in such a way to help facilitate the proper compression of a combusting cycle. Pistons are designed with ring-like spaces called piston ring grooves where the piston rings sit. Piston rings are another degree of separation between the piston and the cylinder wall to prevent metal-on-metal contact to eliminate wear. There are three piston ring grooves where three different piston rings sit. From top to bottom, the top ring is called the compression ring. The middle ring is in the middle obviously and the third ring at the bottom is called the oils ring. Each ring performs specific tasks ensuring proper combustion. Piston rings are usually made from cast iron and steel. The material of the piston rings is key since their job requires them to be strong and resistant to wear.

Piston rings function

Piston rings have four functions that are key to the combustion process of an engine. The functions are : 

• Creates a proper seal between the combustion chamber and crankcase ensuring there is no cross-contamination of combustion gases and lube oil mixing in either sphere. This is often referred to as blowby. 
• Improves the heat transfer from the combustion cycle unto the piston to the cylinder walls.
• Maintains the proper quantity of oil between the cylinder walls and piston. 
• Regulates engine oil consumption by scraping excess oil back into the oil sump. 

The Three piston rings 

The first piston ring that sits at the top of the piston, job is to create a proper seal from proper compression of the combustion cycle. The second piston ring located in the middle of all three has a double job acting as a secondary seal for the top piston ring and then a secondary oil scraper for the bottom oil ring. 

The oil ring’s main job is to prevent oil from entering the combustion chamber and regulate proper oil flow around the cylinder and back into the crankcase. The oil ring consists of three different rings sandwiched together. The top and bottom parts of an oil ring are scrapers that direct oil back into the crankcase. The middle ring of an oil ring is called the thin expander where its job is to maintain tension between the top and bottom rings of the oil ring. 

What are the signs of bad piston rings?

The most common sign of a bad piston ring is blowby which is the main function of all three rings to prevent. This is where the combustion gases slip past the piston into the crankcase. 

This type of issue can produce a few types of results which are : 

• Decreased engine efficiency 

• Decreased engine power

• Higher emissions 

• Increased Oil Consumption 

What causes piston rings to fail?

Failure of piston rings means that the temperatures inside the combustion chamber are higher than usual. These temperatures can cause the metals to expand only increasing the heat. The increased heat will make the rings more susceptible to wear and eventually fail. Increased heat in the combustion chamber can be caused by improper maintenance and putting the vehicle through harsh operating conditions. 

Piston ring replacement cost

Piston rings are located on the piston located inside the engine, particularly in the engine block with other crucial parts connected. The price of the piston rings alone can cost anywhere from $50 – $170 depending on engine makes and models. However, getting to the piston rings will require a full engine teardown to the heart of the engine. The labor cost can range anywhere from $1000 to $5000 depending on vehicle make and model. 

Conclusion

Pistons and piston rings are the components we have to thank for the proper combustion cycle of an engine. Without them, an engine wouldn’t be worth using. This is why proper maintenance and use of a vehicle must be taken into consideration to extend the lifespan of an engine. As the piston and piston rings have taught us, the engine is a bunch of components all working together to produce mechanical power. Each part plays a key role in getting that done and they all depend on each other for the system to work.