Valves

Valves are a central part of the engine’s cylinder head and have a major impact on how the engine is filled with air and fuel, as well as how the exhaust gases are released again. In a combustion engine, intake valves and exhaust valves work together with the camshaft, valve springs, lifters and seats to control gas exchange precisely. This means the quality, sealing and durability of the valves have a direct effect on engine operation, performance and reliability.

Intake valves are responsible for opening to let the mixture or air into the combustion chamber, while exhaust valves direct the hot exhaust gases away after combustion. Although they work together, they operate under different conditions. Exhaust valves are typically exposed to significantly higher temperatures and greater thermal load, while intake valves must still seal properly, move consistently and fit precisely with the rest of the engine’s valvetrain. For that reason, material choice, valve head, stem diameter, length and surface treatment are important factors when selecting valves.

When choosing engine valves, it is important to consider fitment to the cylinder head, valve type, dimensions, application and load level. There is a difference between valves for standard engines, modified street cars and more demanding motorsport engines. In some projects, the focus is on replacing worn or burnt valves with an original-type part, while in other engine builds stronger performance valves are chosen for higher RPM, higher temperatures or increased cylinder pressure. Valves must fit correctly with valve guides, valve seats, springs, retainers and the rest of the cylinder head setup in order to function properly and remain sealed over time.