The engine performance in terms of power, torque, engine speed, fuel consumption and efficiency is evaluated on the basis of purpose it is being used. In case of tractor engines, if farmer needs more power to pull the tillage implement, it must have high drawbar power and similarly if it requires more power to do the farm operations using rotary power, then engine in tractor must provide maximum PTO power. To relate the engine performance with economy of its usage, specific fuel consumption is also determined. Following are the most commonly used curves to rate the engine performance.
Engine speed vs Torque
Engine speed vs Indicated power, Brake Power & Mechanical efficiency
