Cylinder heads are usually made of which material?

• A. Cast iron.
• B. Steel.
• C. Magnesium alloy.
• D. Aluminium alloy.

Answer: (D)

Cylinder heads must survive very high temperatures and pressures while keeping the engine light and well cooled. Aluminium alloy is the best fit because it is much lighter than cast iron or steel, which helps improve overall engine efficiency and performance. It also conducts heat effectively, aiding in transferring heat from the combustion chamber to the cooling system to prevent overheating. Aluminium can be cast into complex shapes with integrated cooling passages, enabling compact, efficient designs. With the right alloying elements, aluminium heads resist wear and corrosion at the valve seats and in the cooling system, making them durable for modern engines. Cast iron and steel are heavier, which reduces efficiency and handling, while magnesium alloy, though lighter, often lacks the high-temperature strength and corrosion resistance needed for reliable engine operation.