You can always go to a copy shop and get them to print it 11 x 17. Crop the picture carefully to get the subject as big as you can within the 17" paper.
Or crop the picture in half and save it as a new file, then crop the picture with the other half and save that. Print the 2 halves on 81/2 x 11 paper and tape them together, play around to get the size right.
I'm lucky I have an 11 x 17 printer!
Brian