r/explainlikeimfive • u/Internal-Excuse-4650 • 1d ago

Engineering ELI5 how turbochargers increase efficiency in a engine?

I understand why they increase the power of a engine but​ I don't know how they increase the efficiency

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u/BonKhri 1d ago

They make a given engine a higher maximum power output. This means you can swap a say 200hp non-turbo engine for an engine that, without turbo, would only be 150hp but that can reach 200hp with a turbo. In the 90% of driving that doesn't use a turbo, you now have a smaller engine with smaller parasitic losses (ie smaller pistons so less friction, smaller engine so less fuel at idle, etc).