🔍 Key Concepts

• Supercharged two-stroke diesel scavenging – how fresh air is forced into the cylinder and pushes out exhaust. • Difference between piston pumping action vs. pressurized intake air in a two-stroke with a blower/turbo. • Role of intake manifold pressure vs. vacuum in diesel engines.

💭 Think About

• In a supercharged two-stroke diesel, ask yourself: what is actually providing the force to push exhaust gases out when the exhaust ports/valves open? • Is there usually a vacuum in the intake of a supercharged diesel, or is the intake side above atmospheric pressure? How does that affect gas flow? • Consider what happens near the end of the power stroke and beginning of the compression stroke in a uniflow or loop-scavenged two-stroke engine. What gas is entering, and what is it doing to the exhaust?.

✅ Before You Answer

• Verify which component actually creates positive pressure in the cylinder during scavenging: piston motion or pressurized intake air. • Eliminate any options that rely on a vacuum in the intake manifold for a diesel with a supercharger. • Think about whether the fuel charge alone can expel exhaust, or if another pressurized gas is mainly responsible for scavenging in this engine type.