Tex 40 is still classed a lightweight thread v 92 = tex 92
you can break Tex 40 with your hands, V 92 / tex 90 will cut you before it breaks
heavy weight thread are sold by the pound and don't usually have yardage marked on the label. a small cone of V 92 = 1/4 lb @ $18.
last spring I did a few denim quilts ( kings) I quilted one using V 92 and used almost a full cone. my biggest expense on that one was the thread
you'll find a chart in this
http://www.thethreadexchange.com/miv...ad-information