The cylinder head in an engine is the upper portion of the engine block, housing the valves, camshaft, and other essential parts of the combustion process. The shell of the cylinder head refers to its external structure, which encompasses the following features:

1. Material:

• The cylinder head shell of the Mazda R2 is typically made of cast iron or aluminum (depending on the specific application). Cast iron provides strength and durability, especially in diesel engines like the R2, which operate under higher pressures and temperatures.

2. Shape & Design:

• The head shell is designed to fit snugly onto the top of the engine block. It houses several crucial engine components, including the valves, camshaft(s), and injectors (for diesel engines).

• The valve cover sits on top of the cylinder head shell, protecting the camshaft and valves.

3. Combustion Chambers:

• The cylinder head contains the combustion chambers where the fuel is injected and combusted. These chambers are designed for optimal fuel mixing and combustion efficiency, particularly for the diesel R2 engine.

4. Cooling Passages:

• Inside the cylinder head, there are cooling passages where coolant flows through to dissipate the heat generated during combustion. This is crucial for maintaining the engine's operational temperature.

5. Valve Train:

• The cylinder head shell also contains the valve seats, valves, and rocker arms. These parts are essential for controlling the intake and exhaust of gases during the engine's operating cycle.

  • Intake valves let air and fuel mix into the cylinder.

  • Exhaust valves expel the combustion gases.

6. Gasket & Seals:

• The head gasket seals the interface between the cylinder head and engine block, preventing coolant or oil from mixing with combustion gases and ensuring proper compression.

• The seals for the valves and camshafts are also part of this shell to prevent leaks of oil or gases.

7. Camshaft:

• The camshaft(s), usually housed in the cylinder head, control the opening and closing of the intake and exhaust valves. On the Mazda R2, this is typically a single overhead camshaft (SOHC) design.

8. Timing Chain/Belt:

• The timing mechanism connects the camshaft to the crankshaft to ensure that the valves open and close at the correct moments in the engine cycle. The R2 engine uses a timing chain, which is typically housed inside the cylinder head shell.

9. Intake and Exhaust Ports:

• The cylinder head shell features both intake and exhaust ports. The intake ports allow air and fuel to enter the combustion chamber, while the exhaust ports allow gases to exit. The design of these ports affects the engine's overall airflow, power output, and efficiency.