Exhaust engine valve bears continuous high temperature combustion gas impact, inferior ordinary steel valve deforms and cracks rapidly after short mileage. High alloy heat resistant engine valve matches turbocharged and large displacement engines, cutting frequent valve replacement maintenance expense for vehicle owners.
Exhaust valve adopts nickel chromium high temperature alloy raw material to resist one thousand degrees Celsius above exhaust temperature erosion. Ordinary carbon steel engine valve loses surface hardness under long high temperature, producing valve seat gap and engine power drop quickly. Intake valve uses medium alloy material for cost balance.
Whole surface nitriding treatment forms hard protective layer on engine valve head and rod, reducing friction loss cooperating with valve guide. Untreated polished valve wears valve guide inner bore rapidly during reciprocating movement, creating engine oil leakage along valve rod clearance.
Complete engine overhaul needs matched intake exhaust engine valve set together with supporting valve guide. Separate single valve replacement leaves uneven wear gap between old and new components, causing air leakage and unstable cylinder compression pressure after short operation period.
Turbocharged gasoline and diesel engines store full alloy nitrided engine valve inventory, naturally aspirated small displacement vehicles prepare conventional alloy intake exhaust valve. Classified stock avoids mixing high temperature resistant valve for low load models to control overall procurement cost.
