Definition check — what density condition characterizes supercharging? Supercharging is the process of supplying intake air to the cylinder at a density that is __________ the density of the surrounding atmosphere.

Introduction / Context:
Engine power scales with the mass of air trapped in the cylinder. Supercharging or turbocharging compresses the intake air, increasing its density and, consequently, the mass of oxygen available for combustion per cycle.

Given Data / Assumptions:

• Boost device increases manifold absolute pressure above ambient.
• Intercooling may further increase density by reducing temperature after compression.

Concept / Approach:
For a given temperature, density is proportional to absolute pressure (rho ∝ p/T). Supercharging raises p (and with intercooling reduces T), so density exceeds that of ambient air. This allows more fuel at suitable air-fuel ratios, improving specific power without resorting to excessively rich mixtures (in SI) or smokey operation (in CI).

Step-by-Step Solution:
Apply ideal gas relation: rho ∝ p/T.Supercharging increases p; often, intercooling reduces T.Therefore, intake density is greater than ambient density.

Verification / Alternative check:
Boost gauges report manifold pressure above atmospheric. Power gains correlate with increased trapped charge density.

Why Other Options Are Wrong:
Equal to or less than ambient contradicts the defining purpose of supercharging. “Always below ambient” is physically inconsistent with the term.

Common Pitfalls:
Confusing pressure ratio with density when temperature changes; intercooling underscores that density, not just pressure, matters.

Final Answer:
Greater than