🔍 Key Concepts

• Air density vs. temperature and how that affects engine performance • The relationship between intake air mass, combustion, and power in a diesel engine • What determines compression ratio in an engine (design vs. operating conditions)

💭 Think About

• If the intake air is hotter, what happens to its density and the actual mass of air entering each cylinder? How would that influence how much fuel can be burned efficiently? • Does higher intake air temperature generally improve or reduce the maximum power an engine can produce, and why? • Is compression ratio something that changes with intake conditions, or is it fixed by the engine’s mechanical design (piston stroke, cylinder volume, etc.)?

✅ Before You Answer

• Verify whether compression ratio is a fixed geometric property or a variable operating condition. • Consider whether efficiency and fuel economy usually increase or decrease when the engine is breathing hotter, less dense air. • Think about peak horsepower: does an engine typically make more or less peak power with hot intake air compared to cool intake air?