🔍 Key Concepts

• Turbocharger flow path: exhaust gases drive the turbine, which drives the compressor to raise intake (inlet manifold) pressure • Pressure relationship between exhaust manifold (driving side) and air inlet manifold (driven/compressed side) in normal operation • Effect of engine speed and load on both exhaust and inlet manifold pressures

💭 Think About

• Think about what must be true for exhaust gas to keep flowing through the turbine and turning it – how does turbine inlet pressure compare with compressor outlet pressure? • Consider normal loaded operation of a turbocharged engine: is exhaust pressure usually higher, lower, or about the same as the boosted inlet air pressure? • For an engine slowing down, does turbo speed (and therefore boost pressure) increase or decrease compared to higher load/speed conditions?

✅ Before You Answer

• Make sure you compare average exhaust manifold pressure (before the turbine) with inlet manifold air pressure (after the compressor) at similar load conditions • Check whether pressure at the turbine wheel is the same as at the impeller (compressor wheel), or if one must be higher to drive the other • Verify whether reduced engine speed normally increases or decreases turbocharger boost pressure in basic diesel engine operation