Talking of Mechanical Engineering:
Thanks to the reservation system, it depends on your caste. If you’re from SC/ST, a rank of somewhere around 200 would be enough. If you belong to the OBC categories then a rank of around 100–150 would do.
Here comes the big one!
If you’re from general category, you need to have a rank of around 25!!! Yes it’s “25” only.
Speaking of other branches, you can just take twice the ranks I mentioned.