81 marks is approximately 93.47 percentile and that is an All India Rank of 69271. You haven't mentioned the Home State you belong to. Nevertheless, going by previous years data, the chances of you securing a seat in various Colleges are as follows:

Rewa Engineering College

Ujjain Engineering College

UIET, Chandigarh

In 2019, the cut off rank for UIET Chandigarh under General Category was 71660. So with your rank, you might have decent chances at UIET, Chandigarh. Now this is based on 2019 data and cut offs change every year. Cut offs depend on various factors such as total no .of seats available, difficulty of the exam, previous year cut offs, no.of Candidates appearing for the exam and no.of Candidates applying for a course. Please use our College predictor for the complete list of Colleges that you may have a shot at: https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer