Exhaust sizing query

Thread in 'Technical Questions' started by pointz, Jul 11, 2015.

  1. pointz

    pointz Member

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    After my car's mapping i am trying to figure why i suffer lag. I am running a gt2560r and not getting full boost till 4250rpm.

    I have ruled out a few things and now my question is,

    Will the fact i am running a 3" system into a 2.5 catback cause flow problems? Obviously there is now a step in the system that could potentially affect flow.

    Any help would be greatly appreciated.
     
  2. boarder_911

    boarder_911 Member

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    What A/R turbine housing do you have on the GT2560R?

    Is the catback an instant change from 3-2.5 inch?
    Ideally you want that transition as smooth as possible... As there will be for turbulence where the step in diameter is effectively reducing the diameter even further....
     
  3. pointz

    pointz Member

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    I cant remember the turbine size off the top of my head!

    When i had the 3" catback it used to reach full boost by 3.5k rpm.

    Yea it goes from 3-2.5 with a step.
     
  4. Stavros

    Stavros Active Member

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    If it used to boost that much sooner, and nothing else has changed, and there's no leaks, you've answered the question yourself.
     

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