🔍 Key Concepts

• compression ignition in diesel engines • relationship between cranking speed, compression temperature, and fuel ignition • difference between diesel ignition and gasoline spark ignition

💭 Think About

• Think about how a diesel engine ignites its fuel. Does it rely on a spark or on very hot compressed air? • If the piston is moving slowly while cranking, what happens to the temperature of the air being compressed inside the cylinder? • Which of the answer choices clearly belongs to gasoline (spark-ignition) engines rather than diesel (compression-ignition) engines?

✅ Before You Answer

• Verify which option refers to heat of compression and how that affects ignition in a diesel engine. • Eliminate any choice that talks about components diesels do not normally use for ignition. • Check which option would most directly prevent the fuel from igniting during low-speed cranking, rather than affecting lubrication or fuel timing only.