🔍 Key Concepts

• How a four-cycle diesel engine normally breathes without extra equipment • The difference between forced induction (turbochargers, blowers) and other air‑supply methods • Typical devices used only for starting or fuel mixing, not for providing normal combustion air

💭 Think About

• Ask yourself: if the question already mentions turbochargers and blowers (both forced‑induction devices), what is the third general way an engine can get air? • Which option describes a condition where the engine draws in air by itself during the intake stroke, instead of being pushed in by external equipment? • Which choices are mainly used for starting an engine or for gasoline engines, rather than for routine air supply in diesel operation?

✅ Before You Answer

• Eliminate any option that is mainly used for starting, not continuous air supply during normal running • Eliminate anything typically associated with gasoline engines rather than diesel engines • Pick the option that describes air entering due to the piston’s own suction on the intake stroke, without external compression equipment