Today, dollar for dollar, is the 318 faster than the 340 ???

Jadaharabi said
From Grant rings in California.


Materials And Coatings


View attachment 1715779152Grant uses the latest materials and coatings available to keep pace with the growing trends in engine technology. We offer a variety of materials and coatings for piston rings ranging in diameter from 40mm to 340mm, in a wide variety of profiles and joint types.

We also offer different versions of piston rings sets to give you a choice of performance and price level. Whatever Grant ring set you choose, you can be assured that quality is built in.



The Ideal Ring Set For The Job
  • High-Strength Ductile Iron Material For Extended Life
  • Steel Material For Maximum Durability Under Extreme Load Conditions
  • Phosphate Coated (Plain) Gray Cast Iron Rings For Economy Re-Ring Jobs.
  • Chrome Coated Rings For Maximum Resistance To Wear And Scuffing
  • Plasma-Moly Coated Rings For Improved Lubrication And Seating


Plain Cast Iron Piston Ring Sets:
View attachment 1715779153These ring sets contain compression rings which are manufactured to precision specifications from high grade grey iron castings The top compression rings are black phosphate coated and normally beveled on the inside top, which gives a torsional twist characteristic or relieved on the lower ridge for oil scraping characteristics. The second compression ring is normally a scraper ring commonly used in the second groove. Oil rings are generally 3-piece circumferential style, which provide quick seating, positive oil control and long life.

Plain ring sets are identified with no prefix or a “P” prefix, example: 2271.020 or P2271.020



Chrome Cast Iron Piston Ring Sets:
View attachment 1715779154These ring sets have a top compression ring that is chrome plated for resistance to wear and scuffing. High strength iron is used where applicable. Intermediate rings are of Torsional twist design. Oil rings are of either circumferential design or Grant’s patented channel oil ring, both of which provide quick seating, positive oil control and long life.

Chrome ring sets are identified with a “C” prefix, example: C2271.020



Chrome Steel Piston Ring Sets:
View attachment 1715779155These ring sets have a top compression ring that is chrome plated and lapped for resistance to wear and scuffing, and faster seating. Steel material is used for high strength and excellent fatigue resistance. Intermediate rings are of Torsional twist design. Oil rings are of either circumferential design or Grant’s patented channel oil ring, both of which provide quick seating, positive oil control and long life.

Chrome ring sets are identified with an “S” prefix, example: S2271.020



Moly Piston Ring Sets:
View attachment 1715779156These ring sets have a top compression ring which contains a section of 100% pure molybdenum with a melting point of 4730° Fahrenheit (2610° C). This high melting point reduces scuffing; scoring and heat transfer from the piston to the cylinder block. Molybdenum increases lubrication, improves compression and adds longer life as well as working with today’s shorter skirted pistons. The oil ring included with these sets is a three-piece circumferential design, which allows uniform unit wall pressure and efficient oil control.

Moly ring sets are identified with an “M” prefix, example: M2271.020
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Nono of that changes what I posted. As the ring gets thinner it’s harder to keep the moly in the ring. It falls out. Rattle it a bit and it falls out. The correct way to keep oil on the cylinder wall is with the bore finish. Like I said, if your machine shop isn’t using a profilometer on the bores they have no idea what the actual finish is. As a side note, the moly filled ring was originally developed to use in dealerships and shops replacing a defective plain cast iron ring. You could install a moly ring and not hone the cylinder and it would seat, and carry enough oil in the moly to make it seal. Back when the cool guys were using cork bond finishes a moly ring was mandatory because there wasn’t enough RvK to retain the oil. Today, the oil is retained in the bores by proper bore finish and geometry. Thin rings and a proper understanding of bore finish has made the moly ring obsolete, regardless of what Grant or anyone else says. Like a belch from a bad onion the moly ring will hang around because too many refuse to move to new, better technology. I’d say the 1/16-1/16-3/16 ring pack is also obsolete but it’s still hanging around. And the even more archaic 5/64 ring packs that KB won’t update are hanging around too. It’s sad that people refuse to understand how much power it takes to run those big, heavy obsolete ring packages, and how much ring seal they give up using them.