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3" coldside hp limit

Discussion in 'Newbie and Basic Turbo Tech Forum' started by 01snake, Nov 21, 2012.

  1. 01snake

    Joined:
    Oct 30, 2011
    On a 6.0 lq4 88-91mm turbo how much will 3" coldside support?

    upgraded from a 70mm now have all these parts and am hoping I can use them

    car is a drag car and I will neve have more then 1500hp

    Will 3" be enough?
     
    01snake, Nov 21, 2012
    #1

  2. Andy Dorsett

    Joined:
    Jun 23, 2003
    Since a turbo does not increase the cfm into the engine the plumbing between the compressor and turbine need only be the same size as the would be for a N/A engine. Weather or not 3" is enough for a 6L depends on what the engine speed is. The plumbing (again between the compressor and turbine) must match the engine not the turbo. If you only change to a bigger turbo you only need to consider the pre compressor inlet plumbing and post turbine exhaust plumbing.
     
    Andy Dorsett, Nov 21, 2012
    #2

  3. vwdave

    Joined:
    Sep 3, 2006
    How exactly do you match the plumbing to the engine? Is there a formula you follow?
     
    vwdave, Nov 21, 2012
    #3

  4. Andy Dorsett

    Joined:
    Jun 23, 2003
    Theoretically you would calcualte the cfm by cid X rpm X VE / 3456 and then select a pipe size that yields the desired pressure drop for its length (say .5psi). With bends and such this is beyond me. Everytime I've done the math with the Reynolds number and all that jazz and then tested it I was way off. I have never been able to correlate airflow calcs to real results. So for me I calculate the cfm and then take a known good system such as a stock mustang and ratio the area of the pipe for what I need.
     
    Andy Dorsett, Nov 21, 2012
    #4

  5. vwdave

    Joined:
    Sep 3, 2006
    Wouldnt you just in theory match the OD of the pipe to the OD of a proper sized throttle body? Or is there an issue doing that?
     
    vwdave, Nov 22, 2012
    #5

  6. Andy Dorsett

    Joined:
    Jun 23, 2003
    If you know that the throttle body is well sized then yes.
     
    Andy Dorsett, Nov 22, 2012
    #6
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