🔍 Key Concepts

• Diesel engine combustion process compared to gasoline engines • Role of compression in raising air temperature • What conditions are needed to ignite fuel in a diesel cylinder

💭 Think About

• Think about how a diesel engine ignites its fuel without using spark plugs. What has to happen to the air inside the cylinder before fuel is injected? • When you compress a gas, what happens to its temperature and pressure, and how does that affect combustion? • Which of these options describes a primary design requirement of a diesel engine, rather than a side effect or an efficiency concern?

✅ Before You Answer

• Verify how diesel fuel is ignited (mechanically or by heat of compression). • Consider whether pumping losses and fuel consumption are things compression is meant to reduce or increase. • Ask yourself which choice directly relates to the fundamental principle of diesel operation, not just engine performance tuning.