🔍 Key Concepts

• Valve overlap in a four-stroke diesel cycle (relation to intake and exhaust flow) • Purpose of a turbocharger and how it uses exhaust gas energy • Difference between naturally aspirated and turbocharged engines in cylinder scavenging

💭 Think About

• Think about what happens when both intake and exhaust valves are open at the same time—what flow do you want to encourage in a turbocharged engine? • How does a turbocharger change the conditions in the intake and exhaust systems compared with a naturally aspirated engine? • Which option directly benefits cylinder filling and scavenging, rather than just changing temperatures or pressures somewhere else in the system?

✅ Before You Answer

• Identify what increased valve overlap physically does to the gas exchange process. • Decide which choice best relates to improving scavenging (removal of burnt gases) and cylinder filling. • Eliminate any option that focuses only on temperature change without improving gas exchange efficiency.