The primary advantages are extreme wear resistance and exceptional heat resistance.
Unmatched Wear Resistance: Tungsten Carbide is significantly harder than hardened steel or even stellite. This drastically reduces wear, especially in modern engines with aggressive cam profiles and high valve spring pressures. It's virtually immune to valve seat recession caused by unleaded fuels, making it a mandatory upgrade for classic engines.
Superior Heat Resistance: These seats can withstand the extreme temperatures of combustion far better than traditional materials. They resist thermal cracking, deformation, and "guttering" (erosion of the seat), which maintains a perfect seal and protects valve life.
Durability in Harsh Conditions: This makes them the ideal choice for high-horsepower racing engines, turbocharged/supercharged applications, engines running on alternative fuels (like propane or natural gas), and industrial machinery that runs continuously under heavy load.