🔍 Key Concepts

• volumetric efficiency as a measure of how completely the cylinder fills with fresh air on the intake stroke • How airflow into the cylinder is affected by intake path restrictions in a naturally aspirated (non‑turbocharged) engine • The difference between factors that affect how much air gets in vs. factors that affect what happens after the air is inside (combustion, pressure, temperature)

💭 Think About

• Which option directly affects the ease and volume of air flowing into the cylinder during the intake stroke in a naturally aspirated engine? • Which options mainly influence combustion pressure or efficiency after the air-fuel mixture is formed, rather than the actual filling of the cylinder? • For each choice, ask yourself: does this change the amount of air that can physically enter the cylinder at a given speed and load, or does it mainly change how that air is used during combustion?

✅ Before You Answer

• Be clear on the definition of volumetric efficiency: the ratio of the actual amount of air inducted to the theoretical maximum at ambient conditions. • Identify which choices are primarily related to combustion and power output (inside-cylinder pressure, mixture burning) rather than intake filling. • Focus on the factor that most directly affects intake flow area and restriction in a naturally aspirated engine, where no turbo or blower is helping to push air in.