How a Car Works: Engine Valves

What is the function of engine valves?

To control the flow of gases through the intake and exhaust ports.

Where do the valves open and close?

Inside the combustion chamber.

When do the valves open and close?

At the appropriate time during the engine cycle.

What is the minimum number of valves required for an engine?

Two valves.

What are the two minimum required valves?

One intake valve and one exhaust valve.

What is the function of the intake valve?

To allow the air-fuel mixture to enter the combustion chamber.

What is the function of the exhaust valve?

To allow burnt exhaust gases to leave the combustion chamber.

Why are most modern engines classified as multivalve engines?

Because they use more than two valves per cylinder.

What is the advantage of a multivalve engine?

It allows more efficient airflow into and out of the cylinder, producing more power.

Why do multivalve engines produce more power?

Because they improve the flow of intake air and exhaust gases.

Which valve is usually smaller: the intake valve or the exhaust valve?

The exhaust valve.

Why are exhaust valves made from tougher materials than intake valves?

Because they are exposed to much higher temperatures from the exhaust gases.