The IM# system is unique to the Hexcel Corp which manufactures rod blanks. It's the Hexcel company's own internal quality standard rating number system that is unique to the Hexcel Corp. I read that it pertains to the number of graphite fibers in the rod blanks somehow. The less fibers use the higher the modulus number rating. Lower numbers of graphite fibers used means the wall of the tublar blank are thinner. High Modulus means that each fiber is stiffer than a lower modulas rated fiber and less fibers are needed to make the rod as stiff as needed. Stain rating is another system that is use to rate the way the rod behaves I saw that either in a link that someone posted in here or in a magazine somewhere. I think it was an online article that someone posted the link to in the Bill Dance Fishing Talk Forums. I suspect that the G Loomis Rods that are rated IM-8 are better than the IM7 rated rods but I am not really sure.
Here is the link to the article in case you miss it in the other posts on this thread.
http://www.flwoutdoors.com/article.cfm?id=141123
But the other companies have tried to copy Hexcel QA standard number rating system but I am not sure they use the very same standards that Hexcel Company uses. Hexcels QA system is more likely propriatory and specific to them and secrete as well. And not all rod builders buy blank material from Hexcel so these other companys would be using a rating system that is not really related to the Hexcel system. G. Loomis use the Hexcel rod blanks I suspect.
So company XYZ so called IM7 rod may not be the same as a G. Loomis IM7 rated rod. If that makes sense.
My guess is that the IM8 G. Loomis rods would be lighter than a IM7 G. Loomis Rods but may be easier to break if its strain rating is not high.Originally Posted by Denny