External rated contest

Can anybody tell how much rank i need so as to get positive increment in my rating as i have started cp mid of the last year and almost all external rated contest i had given and in all my rating drops even i hit 2 questions without any WA quickly i know there are very less crowd participate in this contest.

Since your rating is 1600+ you need to get a rank of under 500 if on average 2k participant participate in this contest.
This will ensure no loss in your rating.