You have secured a percentile of 51 and an SC category rank of 61601 in JEE Main. Admission to National Institutes of Technology (NITs) depends on several factors, including your category rank, the specific NIT, the branch you are interested in, and the number of available seats under the SC category.

With an SC category rank of 61601, securing a seat in the top-tier NITs and popular branches like Computer Science or Electronics and Communication Engineering might be challenging. These usually have much lower closing ranks for the SC category. However, there are still possibilities for admission to some of the newer NITs or less preferred branches.

The Joint Seat Allocation Authority (JoSAA) conducts the counseling process for admissions to NITs. During the counseling, you will be able to fill in your choices of NITs and branches. The seat allocation will be based on your rank and the availability of seats in your category.

It is advisable to participate in the JoSAA counseling and explore the options available to you. Keep an eye on the cutoff ranks for the SC category in different NITs for the previous years. This will give you a fair idea of your chances. While it might be difficult to get into the most sought-after NITs and branches, there is a possibility of securing admission in other NITs or in branches that have relatively lower cutoff ranks. You should also consider any state-level quotas that might be applicable to you as a resident of West Bengal, which could offer some additional possibilities.