Which statement about volumetric efficiency in boosted engines is true?

• A. It cannot exceed 100 percent.
• B. It may be more than 100 percent in supercharged engines.
• C. It is defined by displacement only.
• D. It is independent of engine design.

Answer: (B)

Volumetric efficiency is a measure of how well the engine fills its cylinders with air compared to the amount that would occupy the displacement under ambient conditions. In a boosted engine, the supercharger or turbocharger raises the intake manifold pressure, increasing air density. This allows more air mass to enter the cylinder on each intake stroke than would be possible at atmospheric pressure, so volumetric efficiency can exceed 100%. The idea that it cannot exceed 100% is not true for boosted systems, and VE depends on how the engine is designed and how its breathing is managed; it’s not determined by displacement alone or independent of design.