In a four-stroke engine, which stroke is the intake stroke?

In a four-stroke engine, which stroke is the intake stroke?

• A. Draws air-fuel mixture into the cylinder.
• B. Compresses the air-fuel mixture.
• C. Ignites the air-fuel mixture.
• D. Exhausts burnt gases from the cylinder.

Answer: (A)

During the intake stroke, the piston moves downward with the intake valve open, creating a low-pressure area that draws the air-fuel mixture into the cylinder. This fills the cylinder in preparation for the next step, the compression stroke, where that mixture is squeezed before ignition. The other strokes involve compressing the mixture, igniting it to produce power, and then exhausting the burnt gases. So the description that matches drawing in the air-fuel mixture describes the intake stroke.

During the intake stroke, the piston moves downward with the intake valve open, creating a low-pressure area that draws the air-fuel mixture into the cylinder. This fills the cylinder in preparation for the next step, the compression stroke, where that mixture is squeezed before ignition. The other strokes involve compressing the mixture, igniting it to produce power, and then exhausting the burnt gases. So the description that matches drawing in the air-fuel mixture describes the intake stroke.