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compressor map question

Discussion in 'Forced Induction' started by micah, Mar 17, 2006.

  1. micah

    micah Senior Member

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    alright now when reading a map, i know that being in the middle (highest effeciency) oval is the sweet spot.
    i know that if you cross the left line your turbo is surging.

    what happens if your touching/crossing the right line?


    now that i have my 300zx turbo back and its just sitting in the yard doing jack shit, im piecing together shit to throw the turbo on my b16.
    its a 60 trim t3 with stage 1 wheel, not sure about other specifics, but i did find some maps for the stock turbo.

    the b16 at various psi's always just touches the right ring

    is there any downside to this besides the fact that im just running at lower efficiency/higher temps?

    if i use this turbo then i can boost for like 600 bucks easy.
    if nothing else it can just be temp until i buy a bigger, more suitable one.
     
  2. micah

    micah Senior Member

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    ^^
     
  3. pissedoffsol

    pissedoffsol RETIRED

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  4. micah

    micah Senior Member

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    the furthest right circle i guess,

    the furthest left circle = surging

    same concept, just different side.

    im thinking it just wont be running very effeciently and will run at higher temps

    [​IMG]
    thats the stock z31 turbo map (ignore colored markings, thats for the vg30)
    map out 1.6 pressure to 26 airflow, then 1.8 to 28. thats 10 and 12 psi on a b16

    both times its right on the 65% effeciency line or just a hairs width to the right of it, its really close.
     
  5. reikoshea

    reikoshea HS Troll...And Mod Moderator VIP

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    i dont think you will have a FATAL problem, but you will definitely have higher temperatures, and in turn lower hp (less air in the charge because of temps). havent ever run a car that far outside the map, but i see it working.
     
  6. pissedoffsol

    pissedoffsol RETIRED

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    i wouldn't worry about it.

    run a good intercooler and call it a day. An EGT will be helpful when tuning too. you can "cool" it down a little by running a little richer in your tune.
     
  7. BlueShadow

    BlueShadow Member

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    If you look at the compressor map you'll see lines going from left to right and ending near a set of numbers (ie. 96,300 and 121,900). These numbers tell you the RPM the compressor fan is turning in that part of the map. The higher the pressure ratio the higher the compressor fan is turning. If the pressure ratio stays the same then increased airflow will mean the compressor fans are turning faster then at a lower airflow rate. If you move too far to the right past the choke line, then you are running at a lower compressor efficiency while at the same time increasing compressor RPM. There's no way to tell how sharply the compressor RPM speed increases after the choke line because if you look at your compressor map, the comp. RPM line is cut off after a certain point. But my guess is the comp. RPM increases quite a bit if you look at how much the comp speed changes at the upper pressure ratio/high airflow limits.
     
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