Basic hardware of a four-stroke diesel engine A typical automotive/compression-ignition cylinder head contains which of the following devices?

Introduction / Context:
Compression-ignition engines operate with air induction and direct fuel injection near the end of compression. The cylinder head must therefore accommodate air exchange components and the high-pressure injector hardware.

Given Data / Assumptions:

• Four-stroke diesel with poppet valves.
• Direct injection or unit injector/rail-based injector located in the head.
• No spark plug is used in normal diesel operation.

Concept / Approach:
Diesel combustion requires: (1) an inlet valve for fresh air, (2) a high-pressure fuel injector (often called fuel injection valve/nozzle assembly) to deliver finely atomized fuel into hot compressed air, and (3) an exhaust valve for burned gases. This hardware mix enables non-premixed, diffusion-dominated combustion after auto-ignition.

Step-by-Step Solution:

Verification / Alternative check:
Cutaway diagrams of modern diesels show two or four valves plus a centrally located injector; glow plugs may be present for cold starting but are not ignition sources in normal running.

Why Other Options Are Wrong:

Premixed upstream fueling (option b) applies to SI carbureted engines; option c includes a spark plug, not used in normal CI; option d misplaces gas-exchange; ports in the piston are not used; two-stroke engines may use ports in the liner, not in the piston.

Common Pitfalls:
Calling the injector “not a valve.” The injector assembly incorporates a spring-loaded needle valve; many texts refer to it as a fuel injection valve.

Final Answer:

An inlet (intake) valve, a fuel injection valve/nozzle assembly, and an exhaust valve