Chrome used today primarily by overseas oems and in industrial engines is a much harder non porous material.
Chrome moly rings break in.
Chrome s extreme density and hardness resists the impingement of dirt into the face of the ring which accelerates cylinder wear and actually contributes to the exhaust gases carrying some of the airborne contaminant out through the exhaust system.
This actually requires that during break in the ring come in contact with the cylinder wall.
Resistance to abrasive wear is considerably better than moly rings but the bores must be perfectly straight and round.
There are dis advantages to using chrome rings.
Molly rings are not as picky and they are easier on the bore than chrome rings.
The plain non chrome rings are softer and break in right away.
With today s rings especially moly faced versions this can be achieved in a very short period of time and certainly within 20 to 30 miles of street driving.
Many use them just because of the chrome and they take longer to break in because of this.
Hope that helped u.
The problem with many chrome faced rings was they were extremely hard and difficult.
Some feel that special honeing is required for chrome.
Break0in time is longer and the ends cannot be filled to increase the end gap.
Chrome has more resistance to scuffing and scoring than cast iron but somewhat less than moly.
Chrome faced rings were a popular option a few years back but now have also succumbed to progress and are rarely employed in modern performance engines.
In wot dyno testing likely the rings are seated by the end of the first few runs.
Most grey cast iron rings specify a 150 to 220 grit with 180 being what we recommend.
Also chrome rings should not be used on engine s that run on propane or natural gas.
Prior to plasma molly rings the easiest on the cylinders were cast then molly after that and finally chrome rings that wear real well but are real hard on the cylinder because they are a harder.
If you want to go modern than plasma molly rings are the way to go.
Chrome faced rings were popular at one time but have lost favor and aren t used much anymore by engine builders.
The chrome are considered stronger and used in most high perfornance high compression engines and those runing nos.