A Different Boost Gauge Question
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TECH Resident
Joined: Jan 2002
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From: Phoenix, AZ
A Different Boost Gauge Question I have the Autometer mechanical gauge . . . and I noticed that when the car is just sitting not running, the gauge is pretty well reading 1psi. Does that mean that when I'm reading 10psi on the gauge it's actually 9? Is there a better way to verify my actual boost, like tapping into a line off the manifold with an accurate gauge?
- Dug
- Dug
TECH Apprentice
Joined: Jan 2004
Posts: 337
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From: Frisco TX (Dallas Area)
The gauge reads Boost (pressure above atmospheric). With the engine off, it's reading actual atmospheric pressure (normally baro 29.97 or 14.7 psi = 0). If the gauge is reading some boost, then the baro is high, 30.xx or so.
Also, if the gauge is referenced (run off a double-sided diaphragm), then the reference is off by the amount you read. If that's the case you can recal by just moving the pointer to 0. It's referenced if it has some sort of tube going to atmosphere with no tube connection. This is all from memory, not from knowing each gauge's construction. HTH
BTW, most mechanical gauges have some "0 error", it's more noticible the smaller the gauge face. It usually doesn't materially effect full reading enough to worry.
Also, if the gauge is referenced (run off a double-sided diaphragm), then the reference is off by the amount you read. If that's the case you can recal by just moving the pointer to 0. It's referenced if it has some sort of tube going to atmosphere with no tube connection. This is all from memory, not from knowing each gauge's construction. HTH
BTW, most mechanical gauges have some "0 error", it's more noticible the smaller the gauge face. It usually doesn't materially effect full reading enough to worry.
Last edited by TeeKay; Oct 26, 2005 at 09:01 PM.
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It is a bad Gauge!!
It should be reading no more and no less than the area in the large white block (0). That is the reason for this large block to compensate for different static altitudes for which the gauge is at, IE elevation.
It should be reading no more and no less than the area in the large white block (0). That is the reason for this large block to compensate for different static altitudes for which the gauge is at, IE elevation.
