my presentage 88% in diploma . it is suitable to goin your college for BE (mechanical ).
As per the eligibility you should have passed the Diploma Examination in Engineering / Technology of the State Board of Technical Education and Training, Tamil Nadu or an equivalent examination for direct admission to second year (Lateral Entry). The minimum marks category wise and other criteria for admissions you can go through with the given below link.
http://rmkec.ac.in/admin/oyap.php
Good Luck!