🔍 Key Concepts

• Cylinder scavenging and how fresh air replaces exhaust gases in diesel engines • Differences in gas exchange between two-stroke and four-stroke diesel cycles • Role of exhaust valve opening area and timing in allowing complete scavenging

💭 Think About

• In which engine cycle does scavenging occur during a very short part of the power process, requiring fast, high-volume gas flow? • How does the presence of separate intake and exhaust strokes affect how critical the exact size of the exhaust valve opening is? • Think about which engine type relies more on overlap between incoming scavenge air and outgoing exhaust through the exhaust valve.

✅ Before You Answer

• Identify in which engine type scavenging is the primary method of clearing the cylinder every power cycle, not just on a separate exhaust stroke • Consider where ports in the liner assist or control scavenging versus where the exhaust valve does most of the work • Check which option best matches the engine type where exhaust valve flow area has the greatest impact on scavenging efficiency