The revolution difference is one of the delivery acceptance test parameters for a two spool turbojet engine.It is adjusted according to a standard revolution map which was established specially for this type of engine.The level of appropriateness of the established map will affect the operating performance

stability and reliability for the engine usage.This paper expounds the establishment of the standard revolution difference map and its usage for a two spool turbojet engine.The uppermost and lowermost limits of the revolution difference map will affect the engine operation.To define the uppermost and lowermost limits two methods were suggested:operation point checking method and stable working range checking method.These two methods are suggested to be jointly used.These methods have been proved successful in a new engine development.