I was referring to common everyday shelf items we buy from our local parts stores, not some custom made one off jobs costing hundreds of dollars, or ring sets that most of us would never purchase
(or need) due to their high price tag.
Chrome moly is a term often misused when describing rings. Do a search for "chrome moly" rings and see what you come up with. Typically it will refer to a common moly ring rather than a high tech, super alloy, chrome moly steel ring set, used primarily for high end racing where budgets are not as stringent as our typical forum member.
To answer the question this topic is all about in the first place:
The guy at the shop said I shouldn't have put in chrome moly rings because they are for high RPM engines and they take forever to seat. Is this true?
Answer:
Speed-Pro top rings are manufactured from high strength Ductile Iron with an exclusive Plasma-Moly facing for instant seating, superior cylinder sealing and optimum durability.
In simple layman terms:
The single most important factor to be considered in selecting the proper compression (top) ring face coating material is the service requirements the engine will be operated under. Will the engine be subjected to unusual speed or load (high temp conditions), stop and go - short trip driving, occasional or regular strip use, or in a high dust or dirt environment?
The three popular types of compression ring face coatings are cast iron, moly, and chrome. Each has advantages of its own with respect to operating conditions. Plain cast iron is a durable wear surface in normal operating conditions and is less costly than the moly or chrome faced rings. Moly rings have a very high resistance to scuff and superior oil control capability. Chrome rings have good resistance to scuff (better than iron) but do not exhibit moly's oil retention capabilities.
For typical light duty service where the vehicle is not subjected to long periods of high speed or load operation and is run primarily on paved streets, plain cast iron is a good choice when not subjected to unusual dirt or heat conditions.
When faced with occasional or continuous high speed and/or load conditions (where the engine is subject to periods of high temperature ranges), moly is a good choice because of its scuff resistance and strength. Moly, which is an acronym for molybdenum, is quite porous in its applied state, which results in excellent retention of oil in the face of the ring. Moly also has the highest melting point of the three popular face coatings which results in its capability to live better under more severe operating conditions, or more specifically, to resist scuffing and scoring. Moly rings are better suited to performance engines in which the rings are expected to serve adequately, through-out the engines entire life.
In a dusty environment encountered while operating on dirt or unpaved roads, chrome is the best choice. As mentioned earlier moly, because of Its porosity, holds oil on the O.D. face of the ring which helps inhibit scuffing. Yet the pores on the material also can serve as a trap for foreign materials. Because the incoming air/fuel mixture will probably contain some abrasive contaminant in a dusty environment, chrome with its smoother O.D. surface, is a better choice. Chrome has more resistance to scuffing and scoring than cast iron, but somewhat less than moly.
Bottom line, this is a great topic with good information for all.
For more information on Speed Pro plasma moly rings:
http://www.federal-mogul.com/cda/content/front/0,2194,2442_897063_8682,00.html
