Optical burst formation is aggregation of incoming packets for same destination, which are switched together. Optical Burst Switch (OBS) allow variable burst formation time and burst sizes which can be so that network resources will be used optimally. In this paper Engset model is mathematically analyzed for the burst blocking probability and burst length for different round trip time, average packet arrival time. The average delay analysis for parameter such as fiber capacity a burst size is made using a delay model. The simulation result relates the fiber capacity and burst size for the given traffic with the average delay. It helps in choosing the appropriate fiber capacity and burst size to handle higher traffic load.