Perhaps I'm overlooking the obvious, but …
(1) If you print your large graphic to an 11 x 17″ size at 100%, it's pretty obvious you get only a part of it.
(2) Equally, if you size-to-fit, your image will be reduced in size (how much depends on the original size, but I'm eyeballing it at about 10%).
It's kind of hard to get the gist of your question; are you hoping for a trick that magically enlarges the max size of your printer?
You can get there halfway (or so I believe) if you use 'manual tiling', something that you can do in InDesign's Print Dialog, and possibly also from within Acrobat.