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Manifold pressure gauge

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Aircraft Systems

In basic terms, what does a manifold pressure gauge do?

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1 Answers



  1. Wes Beard on Jun 06, 2015

    Simply put, the manifold pressure gauge measures the pressure inside the manifold at all times… whether the engine is running or not.

    When the engine is off air is allowed to freely enter and exit the manifold and the pressure gauge will read ambient pressure. At sea level approximately 30″.

    With the engine at idle, the throttle body will inhibit free air into the manifold and the pressure drops as the airflow is still allowed to exit. As the throttle body opens, it allows more airflow into the manifold and the pressure rises.

    At no point would you be able to get a higher manifold reading than outside ambient pressure unless you are operating a super or turbo charged airplane.

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