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MAP Readings: Where should they be?

Old 04-05-2009, 10:26 PM
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Default MAP Readings: Where should they be?

Durring WOT what should my MAP be reading? Assuming I have an intake that is non restrictive. How low would it need to be to indicate that I need a better flowing intake? I am reading between 96 and 98kpa. Am I even looking in the right place to see if I have a limitation here? Please advise.
Old 04-06-2009, 06:52 AM
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Assuming you are N/A and running a 1 bar MAP:
A 1 bar MAP is spec'ed from 15 to 102 kPa. So you are within 2-3% of the max, which may be attributed to normal errors, such as manufacturing tolerances, voltage loss through wiring, etc.
Old 04-06-2009, 08:52 AM
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I am NA. It is the factory MAP. I just want to know what other people are reading at WOT. Particularly with a cam.
Old 04-06-2009, 10:18 AM
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You need to know what your Baro reading is. Max sensor value is not what you should be comparing to.
Old 04-06-2009, 12:29 PM
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I thought I could use the MAP since it is measuring the pressure/vacuum in the mannifold. I have added Baro to my log file. What should I look for as far as readings for this?
Old 04-06-2009, 12:30 PM
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As the one poster indicated, the maximum MAP reading you can hit (NA) at 100% TPS, will be the barometric pressure on that day.

Near sea level that would be ~101.1 Kpa. If you are hitting 98 Kpa in Chicago, that sounds about right. If you want to hit higher, just try it on a day when their is a high pressure system overhead.

I am cammed, but at this elevation (5440') the most we hit NA is ~82-84 Kpa. Up Vail pass, I would be lucky to hit 70 Kpa.

As long as you have no intake leaks, your MAP readings are normal. A bad air filter or intake could restrict flow, but NA your max is determined by elevation and that days atmospheric pressure reading.

..WeathermanShawn..
Old 04-06-2009, 01:13 PM
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OK. This all makes sense.

Then how do I determine if my intake is restricting my engine? I would think it would pull vacuum at WOT if it were? Maybe I am mistaken.
Old 04-06-2009, 02:01 PM
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I believe with ignition key on, you can log your barometric pressure (Kpa). It should match the current atmospheric pressure.

I guess you could make several runs with various air intake configurations. If there is a substantial difference you might have an intake restriction.

If I remember my math/engineering correctly, MAP and vacuum is an inverse relationship. MAP up, vacuum down? Vacuum at WOT should be near zero.

Log Baro, Vacuum, and MAP. Sounds like you are within 98% of normal on your WOT MAP.

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