In a piston engine, which stroke draws the air-fuel mixture into the cylinder?

In a piston engine, which stroke draws the air-fuel mixture into the cylinder?

• A. Intake - Piston moves downward drawing a fresh charge of vaporized fuel/air mixture
• B. Compression - Piston moves upward compressing the fuel/air mixture
• C. Power - Spark ignites the mixture
• D. Exhaust - Exhaust valve opens

Answer: (A)

During the four-stroke cycle, the intake stroke is the downward travel of the piston with the intake valve open. This downward motion increases the cylinder’s volume and lowers the pressure, creating suction that draws the fresh air-fuel mixture from the intake system into the cylinder. The other strokes are responsible for compressing the mixture, igniting and powering the piston, and then exhausting the burnt gases.

During the four-stroke cycle, the intake stroke is the downward travel of the piston with the intake valve open. This downward motion increases the cylinder’s volume and lowers the pressure, creating suction that draws the fresh air-fuel mixture from the intake system into the cylinder. The other strokes are responsible for compressing the mixture, igniting and powering the piston, and then exhausting the burnt gases.