🔍 Key Concepts

• the effect of early fuel injection timing on peak cylinder pressure in a diesel engine • the relationship between combustion timing and exhaust gas temperature • how too-early combustion changes when and where heat is released in the power stroke

💭 Think About

• Think about what happens if most of the fuel burns before the piston reaches top dead center versus just after top dead center. How does that affect maximum firing pressure? • If combustion happens earlier in the cycle, does more of the expansion work happen while the piston is still coming up or going down? How would that change the heat left in the exhaust? • Compare in your mind: late injection (after TDC) vs early injection (before TDC). Which one tends to waste more heat out the stack, and which one tends to create higher peak pressure in the cylinder?

✅ Before You Answer

• Be clear on the typical symptoms of early vs late injection timing (pressure vs temperature trends). • Check which combination logically matches earlier-than-normal peak pressure during compression/combustion. • Verify that your choice matches a condition where combustion starts too soon in relation to piston position near TDC.