🔍 Key Concepts

• Diesel engine operating principle compared to gasoline (petrol) engines • How fuel is introduced and burned inside the cylinder • Role of compression and temperature in starting combustion

💭 Think About

• Ask yourself: In a diesel engine, what actually starts the burning of the fuel once it is inside the cylinder? • Compare: In a gasoline engine, how is the fuel–air mixture ignited, and what is different about that in a diesel? • Which of the choices directly relates to how combustion begins, rather than how air is moved, valves operate, or the engine is cooled?

✅ Before You Answer

• Be clear on how compression ratio affects temperature in a diesel engine • Identify which choice deals with the start of combustion (ignition), not just general engine hardware • Eliminate any options that are common to both diesel and gasoline engines, focusing on what is unique to diesel