Explain why turbocharged engines may have inferior values of power output and fuel consumption than naturally aspirated engines especially at low speed.

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written 8.5 years ago by

teamques10 ★ 68k

The problematic operation for turbocharged engines is located in the low speed and medium-high load operating range. Here the turbocharger compressor delivery pressure and hence the air fuel ratio are still low since exhaust gas enthalpy is not yet capable of providing the required power to boost the compressor. So the turbocharged engines have inferior power output and fuel consumption at these operating conditions compared to naturally aspirated engines.
Another possibility could be development of increased engine exhaust back pressure which may affect the performance of the turbocharger, by causing changes in the air-fuel ratio and fuel enrichment. This leads to engine performance problems and increase in emissions. The magnitude of the effect depends on type of air charge systems.
The efficiency of the turbine blades is very sensitive to gas velocity. Hence it is very difficult to obtain good efficiency and power output over a wide range of operations for turbochargers.

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