🔍 Key Concepts

• differences in temperature and corrosion between intake and exhaust gas flows in a diesel engine • material selection for valve faces and seats under high heat and chemical attack • why low-alloy steel can be acceptable in cooler, less aggressive environments

💭 Think About

• Which valve (intake or exhaust) is exposed to the hottest, most chemically aggressive gases in the cylinder? • What is the main reason you might choose a more expensive, heat- and corrosion-resistant alloy for a component? • Looking at the answer choices, which ones talk about mechanical geometry or flow volume, and which ones talk about the gas environment and corrosion?

✅ Before You Answer

• Identify which side (intake vs exhaust) sees hot combustion and exhaust gases and which side only sees fresh air (or air-fuel mixture). • Ask yourself if self-centering or flow volume directly justify using a cheaper material like low-alloy steel. • Focus on the choice that links material selection to the absence or presence of hot, corrosive exhaust gases.