[Elcoman]

Is there a diffrence between plasma and moly rings? And which would be better for a street/strip BBC motor mostly street?

 

[Elcoman]

anybody?

 

[HP Hunter]

The plasma-moly and the standard moly rings use the same material for both. The difference is how the moly is installed on the ring itself.

The original moly rings use a fill type of moly between two outer rails, as technology improved the manufacturers were able to spray the moly on the outer face of the ring. This type will withstand more abuse than the filled type. Either type will do an excellent job when it's appropriate for the application.

The plasma faced ring is superior but more expensive. Some engines will need a stainless ring to survive. If your's is a street engine with some limited track use you will be fine with a filled moly ring. This type of ring
has mostly been supplied in the standard engine building kits where ring gaps are not hand fitted and the time to seat them is fairly quick with the moly.

Harry P. Hunter

 

[engineguy]

When moly was first used in piston rings, a groove was cut into the center of the ring and moly was applied to (filled) in this groove. Then the OD of the ring was finished. These rings were usually grey iron. In most cases, moly-filled rings still utilize grey iron base material for the ring.
In subsequent years, ductile iron has been used for top rings in high performance applications. As stated in a previous post, plasma moly is sprayed onto the face of the ductile ring, under very controlled temperature, and then the final OD of the ring is finished. Just about all high performance rings now use ductile iron or steel for the top ring, with plasma moly spray.
Filled moly and plasma moly have about the same physical characteristics and will work just as well in most applications. For severe usage (that's most of us), ductile iron or steel top ring with plasma moly face will survive much better.

 

[Elcoman]

Thanks for the replies. I am going to go with the plasmamoly.

 

[Elcoman]

I bought the Moly rings instead. Plasma was B/O until 4/26