"To verify the results, the test with the fractional rings was run twice. That ring package generated about 15 degrees higher water temperature and nearly 20 degrees higher oil temperature compared to the thinner metric ring set.
The results confirm piston-ring-to-cylinder-wall friction as a meaningful contributor to engine operating temperature, and identifying friction as the source of the heat was quite easy. The standard fractional rings reduced engine power by nearly 20 lb-ft of torque and more than 15 hp compared to the gas-ported metric ring set.
...
Motor oil provides as much as 40% of piston cooling, so a hotter piston would lead to hotter oil. However, in both the dyno and real-world tests, the oil temperature decreased along with the water temperature.
...
By going to thinner piston rings, friction can be significantly reduced, and the benefits are increased horsepower and reduced operating temperatures.
Does this performance increase come at a cost in durability? The answer is no. Back to the test at Shaver's—used oil samples were taken from each test cycle and analyzed by an independent oil lab. Those results revealed a 55% reduction in wear by going to the thinner rings.
...
Automakers have gone from thicker, cast-iron rings to thinner, steel rings over the last several decades. Why? Primarily to improve fuel economy, but as a convenient side-effect, today's engines also last much longer than before.
...
It's not hard to find off-the-shelf pistons these days with either 1.0mm/1.0mm/2.0mm or .043-inch/.043-inch/3.0mm ring grooves."
https://www.motortrend.com/how-to/piston-rings-versus-engine-temperatures/
The results confirm piston-ring-to-cylinder-wall friction as a meaningful contributor to engine operating temperature, and identifying friction as the source of the heat was quite easy. The standard fractional rings reduced engine power by nearly 20 lb-ft of torque and more than 15 hp compared to the gas-ported metric ring set.
...
Motor oil provides as much as 40% of piston cooling, so a hotter piston would lead to hotter oil. However, in both the dyno and real-world tests, the oil temperature decreased along with the water temperature.
...
By going to thinner piston rings, friction can be significantly reduced, and the benefits are increased horsepower and reduced operating temperatures.
Does this performance increase come at a cost in durability? The answer is no. Back to the test at Shaver's—used oil samples were taken from each test cycle and analyzed by an independent oil lab. Those results revealed a 55% reduction in wear by going to the thinner rings.
...
Automakers have gone from thicker, cast-iron rings to thinner, steel rings over the last several decades. Why? Primarily to improve fuel economy, but as a convenient side-effect, today's engines also last much longer than before.
...
It's not hard to find off-the-shelf pistons these days with either 1.0mm/1.0mm/2.0mm or .043-inch/.043-inch/3.0mm ring grooves."
https://www.motortrend.com/how-to/piston-rings-versus-engine-temperatures/
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