The principle of supercharging is to ______ the density of the fuel-air charge, before it enters the ______.

• A. Increase, Cylinders
• B. Decrease, Cylinders
• C. Increase, Manifold
• D. Increase, Turbocharger

Answer: (A)

Supercharging works by forcing more air into the engine so the density of the air-fuel charge is increased before it enters the cylinders. With more dense charge (more air and hence more oxygen), more fuel can be burnt each cycle, producing more power overall. The compressor that does this is the supercharger, and the dense charge then moves through the intake and into the cylinders. Saying the density is increased before it enters the cylinders is the accurate way to describe what supercharging accomplishes. The other phrasing would misplace where the density boost happens or mix in a different device (turbos use a turbine-driven compressor, not a mechanical supercharger), which is why they don’t fit as well.