Stock non-PP shows max boost of 24psi

Discussion in 'Generation 4 - General Discusson' started by Jeff2017, Nov 16, 2018.

  1. Jeff2017

    Jeff2017 SHO Member

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    I am monitoring my absolute manifold pressure with my BlueDriver OBDII app and when flooring the car I am seeing 24psi of boost. I guess this is normal but I thought the 2-bar map could only accurately measure 14psi
    or so. Just wondering why the stock boost is so high with a 2-bar map. Excuse my ignorance:)
     
    Last edited: Nov 16, 2018
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  2. SHOdded

    SHOdded SHO Member

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    assuming it IS giving you boost and not absolute pressure, seems high for Stock OR Livernois tunes. Unleashed and others, yeah, seen those 24-25 psi spikes. What does it read at idle when there should be NO boost?
     
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  3. Johnbigdog

    Johnbigdog SHO Member

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    Manifold absolute pressure and gauged pressures are two different animals. Remember there is about 14 psi (depending on altitude) pushing down on you at all times. MAP will register that key on engine off, gauged will show nothing.
     
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  4. Jeff2017

    Jeff2017 SHO Member

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    At idle it is reading around 5psi
     
  5. Jeff2017

    Jeff2017 SHO Member

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    I see, so really I am really getting about 10 PSI of boost assuming default 14.3 PSI at 740 ft. above sea level.
     
  6. Johnbigdog

    Johnbigdog SHO Member

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    :) you got it.

    Btw, it fools some of the best of them too.
     
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  7. krewat

    krewat SHO Member

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    Yeah, I think the most I ever saw my 2013 go to (stock) was 10-12.
     
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  8. twobitcoder

    twobitcoder New Member

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    I would be surprised if it was 10 psi. The M90 on my 2006 Mustang GT with pulley and tune reported 10 psi of active boost. Maybe 5 for each turbo? Ok, maybe, but doesnt feel like it. 10 psi means a lot more in a 3.5l engine than it does in a 4.6l. My butt and experience and mpg hints at 5-6.
     
  9. Johnbigdog

    Johnbigdog SHO Member

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    The compressors are making 10 psi of pressure above atmospheric. With small compressors they can build that pressure quickly and provide the volume needed up to a point. Running out of boost really means your running out of volume. (Our car can run off of one turbo, just not well) No different then your home shop air compressor. You need to match the compressor with the volume of air you need/want.

    Another thought. If you fill a 10 Gallo compressor with 10 psi, and another portable 10 gallon tank with 10 psi and conect them pneumatically, how much pressure do you have.

    What is different is your mustang had more displacement, 2 extra cylinders and possibly a different compression ratio cams, Intake design.... You can't compare two different engines that have a similar boost pressure and expect the same output.
     
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