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Turbo boost pressure?

Discussion in 'Land Rover Freelander' started by Labiarat, May 12, 2013.

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  1. Labiarat

    Labiarat Active Member

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    Does anyone know what a healthy TD4 turbo boost pressure would be? Ive done the searches but no luck :confused:
     
  2. hd3

    hd3 Well-Known Member

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    i've seen mine up to 28 psi ..
    that was uphill in 4th gear .. @ about 3.6k rpm .. go-pedal on floor ..

    only know that by glancing at a 'scangaugeII' for a split second
    as i was more concerned with watching the road at the time ..

    don't know if it would go any higher .. i've not tried to find out ..

    regular driving .. normaly runs between 15 to 21 psi .. depending on engine loading ..

    ~~~~~~~~~~~~

    a.f.a.i.k. my td4 be in good health :)

    ~~~~~~~~~~~~~~~~

    i think .. but not 100% sure .. that 30 psi or so ( aprox. ) be about a top-boost average for most stock diesels ..
     
    Last edited: May 12, 2013
  3. Labiarat

    Labiarat Active Member

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    hmm sounds like mine is under boosting then as I am only getting 15-16psi im using dash command
     
  4. Labiarat

    Labiarat Active Member

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    Thanks for the reply HD3, anyone else with any figs for comparison?
     
  5. matacaibo

    matacaibo Active Member

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    Mine peaks at 215 Kpa absolute when accelerating hard, thats 2.15 bar absolute, about 30 psia, because its absolute pressure you are only getting about 15 - 16 psi of boost press.
     
  6. matacaibo

    matacaibo Active Member

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    Might be measuring in psig, if it is add 14.7 psi to convert to psia
     
  7. hd3

    hd3 Well-Known Member

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    does 'dash-command' read the MAP sensor for that ??

    ( i should have clarified .. my 'scangauge' reading was from the map sensor ..
    ( i.e. manifold-absolute-pressure ..
    ( not sure from where else one would get the boost info from the standard sensors on the td4
     
  8. hd3

    hd3 Well-Known Member

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    cheers .. just now learnt somethin' new :)

    had never heard of 'psia' and 'psig' .. 'till now ..

    a quick Google search clarified that one ..
     
  9. matacaibo

    matacaibo Active Member

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    Yeah, if your reading goes below 14.7 psia its actually pulling a vacuum, think I might have some graphs somewhere, if I can find them I will post them ;)
     
  10. matacaibo

    matacaibo Active Member

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    Heres a graph I recorded using Palmer PCMSCAN software & a Mobydick OBDII scanner, unfortunately the MAP pressure is in "Hg (inches of mercury), but Atmospheric pressure is normally about 29 - 30 "Hg. with the throttle open 100% boost pressure was about 65 "Hg or about 30 psia which equates to about 16 psi of boost

    [​IMG]
     
  11. hd3

    hd3 Well-Known Member

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    or one is situated fairly higher than sea-level .. engine at idle .. ??
    saw mine at 13.9 once ( @ idle ) .. was wondering what was going on 'till i realised were i was ..
    ( hopefully that was the explanation .. 'n not something worse :)
     
    Last edited: May 13, 2013
  12. matacaibo

    matacaibo Active Member

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    Where were you, half way up an Alp ;)
     
  13. Labiarat

    Labiarat Active Member

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    Wow thankyou for the info, I will go back and have a look to confirm but... as the dashcommand has two readings one of which is the MAP which tops about 220kpa and another giving boost pressure. Whats confusing is the haynes manual stating the turbo max boost is 1.75 bar which is 25psi give or take
     
  14. hd3

    hd3 Well-Known Member

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    no alps here .. just some big hills ..

    i think it were 'see attached pic'
    were about a week or two after the last major snowfall ..
    i went up there to see if the road was open
    ( ignoring 'road closed' signs )
    road had been bulldozed closed with snow .. i went around the first barrier
    but next one would have needed a shovel ..
    then i saw the height of snow above the road sides 'n figured it had been closed
    due to the possibility of that snow bank collapsing onto the road and burying a vehicle
    so .. i turned around .. sat 'n drank coffee whilst enjoying the view ( clear sunny day )

    "A" on the pic is at 582 metres

    figures .. as at about 500 metres .. 13.9 psi ( 95 kPa ) makes sense ..
    https://en.wikipedia.org/wiki/File:Atmospheric_Pressure_vs._Altitude.png

    ( sub to .. https://en.wikipedia.org/wiki/Atmospheric_pressure )

    trivial height info by county ..
    List of English counties by highest point - Wikipedia, the free encyclopedia


    my Haynes has neglected to include that info :-(
    i've a tuning box that adds about 33bhp to the stock 112bhp
    so i guess that might account for more boost that standard at higher rpm ..
    ( i don't know what psi would be an 'over-boost' occurence ..
    ( in which case the ecu puts the engine into 'limp mode' for self preservation
     

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    Last edited: May 13, 2013
  15. matacaibo

    matacaibo Active Member

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    Its generally accepted that Boost pressure is the additional pressure above atmospheric pressure or psig, MAP (manifold absolute pressure) is the pressure above absolute vacuum. So the figure from Haynes is wrong for either !!!, doesn't surprise me, the Haynes manual for the Freelander 1 facelift has several errors.
    My first Freelander was a manual TD4 facelift without any form of tuning & my current one is an automatic TD4 facelift with a Roveron Synergy II with the wick turned right up !!, boost pressures are practically identical when compared to RPM, I haven't got my head around that yet !!
     
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