See as you are from sc category and you got 77 percentile. But you should be saying your rank. At the time of writing this question , JEE mains results were out earlier. So you are having the rank with you. 

I would suggest you to go and visit josaa website and see previous 2 to 3 years closing rank of nit Trichy . It will give you an idea that by how much will rank increase this year. You will know there better rather than asking questions here as you are determined to go for nit Trichy.

Thank you.