I don't understand - if the conversion is successful and the output is larger than the input, what shall we help if you can't get more available space? I doubt any other tool will let you have a smaller output - else there could be something wrong if one tool brings another output than the other.
So with what do you need help please
Try getting more space, maybe temporary from your SAN guys or ask a coworker if he has sufficient space somewhere on one of his servers where you can convert your stuff.
to be more clear,
I first do
cat file | od -Ad -x
Now, after this I do cuts using dd command
Now, output of
cat file | od -Ad -x
actually becomes twice the size. I dont know if there is any alternative for above.
I am doing this to grep for some pattern from above hex output.