Could this be a dumb question about boost!?
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It is an absolute gauge. Pressure absolute takes into account the atmospheric pressure where as "gauge pressure is pressure above absolute. Atmospheric pressure (1 bar) is 14.7 PSI. So on an absolute gauge one PSI of "boost" is 16PSI absolute. Whereas a "gauge pressure" gauge would read 1 PSI.
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actually its the suction from the engine running that causes the negative pressure. With the throttle plates closed and the car running the engine is pulling in more air than what is in the plenum meaning the air pressure inside the chamber is actually negative.
If it was reading absolute atmospheric pressure it would read negative with the ignition switch "on" and the car not running
If it was reading absolute atmospheric pressure it would read negative with the ignition switch "on" and the car not running
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the negative on the gauge can help determine if you have a vaccum leak as well
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simple. at low enough RPM, intake airflow > charge air movement, hence vacuum. eventually, charge air > intake air thereby, boost (positive pressure).
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Hahaha! I spent my entire career manipulating the English language. You beat me in one sentence.
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Lol i thought i kept it simple
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Oh, you did. But I'm simpler than mere simple
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haha that's high praise! im just happy to help.
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