Induction and Engine Airflow Systems Which of the following statements regarding volumetric efficiency of an engine is true? a. The volumetric efficiency of an engine will remain the same regardless of the amount of throttle opening. b. It is impossible to exceed 100 percent volumetric efficiency of any engine regardless of the type of supercharger used. c. It is possible to exceed 100 percent volumetric efficiency of some engines by the use of superchargers of the proper type.