well,the score needed is based completely on the level of paper.....first of all u should consider that mech is most demanding course after naval architecture and ship building in CUSAT....AND considering the last rank admitted last year its 1097 in free seat and 698 in payment seat ,since u r non keralite u would be eligible for payment seat and hence to get a rank within 600,u really need to give ur best.......score 600+(just an assumption)....Give ur best and pray :)