🔍 Key Concepts

• Fuel injection timing in a diesel engine and what "retardation" means • Relationship between injection timing and combustion start in relation to piston position (before/after top dead center) • Effects of late combustion on power output, temperature/pressure in the cylinder, and fuel economy

💭 Think About

• Think about what happens if the fuel burns later in the power stroke instead of near top dead center. How does that change the useful work on the piston? • Compare "ignition lag" with "injection timing": are they the same thing, or does one affect the other indirectly? • Which of the options (power, ignition, economy) is most sensitive to the burning occurring too late in the cycle?

✅ Before You Answer

• Be clear on what "retarding injection" means: fuel injected later than normal, closer to or even after top dead center • Decide whether later burning would normally give more or less complete expansion and thus more or less work on the piston • Check if later combustion is more likely to improve or worsen fuel economy and if it tends to increase or decrease maximum cylinder pressure and power