Inlet Valves
* Head: Typically made from steel or stainless steel. These materials are strong and resistant to heat and wear.
* Stem: Also usually made from steel or stainless steel.
* Face: This is the part that seals against the valve seat. It can be:
* Hardened steel: For increased durability and wear resistance.
* Nickel-chrome alloy: Offers good heat resistance.
* Stellite: An extremely hard and wear-resistant material, often used for high-performance applications.
Exhaust Valves
* Head: Exhaust valves face the most extreme conditions (high heat, exhaust gases). So they're often made from:
* Stainless steel: Offers excellent heat resistance and strength.
* Nickel-chrome alloys: Provide high-temperature strength and resistance to corrosion.
* Stellite: Used in high-performance engines for its incredible durability and resistance to wear and heat.
* Stem: Similar to inlet valves, they're usually made from steel or stainless steel.
* Face: This is the part that seals against the valve seat. It's often made from hardened steel, nickel-chrome alloy, or stellite, just like the inlet valve.
Factors Affecting Material Choice:
* Engine Type: High-performance engines will often use more exotic materials for better durability and heat resistance.
* Fuel Type: Diesel engines, for example, operate at higher temperatures, so their exhaust valves may require even more robust materials.
* Operating Conditions: Factors like engine speed and load will also influence the materials used.
In Summary:
Inlet and exhaust valves are carefully engineered components that are subjected to significant stress and heat. The materials used for these valves are chosen to maximize their performance, durability, and resistance to high temperatures and wear.
