VGT/VNT vs Wastegated Turbo - Which is Better for MPG?

Discussion in 'Trucks [ Eighteen Wheelers ]' started by rbrauns, Aug 4, 2020.

  1. rbrauns

    rbrauns Light Load Member

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    Ok. I've got a fuel sucking Detroit Series 60 DDEC 6 but I am super confused as to which turbo type will give the best fuel economy.

    The pre emission Series 60 are legendary for getting good fuel economy and they used fixed vane turbos with a wastegate.

    My tuner says that a fixed vane turbo will give the best fuel economy.

    This site says VGT for emissions but fixed vane with a wastegate for fuel economy:

    https://www.google.com/url?sa=t&sou...FjABegQICxAG&usg=AOvVaw0aH9eCQOs6U77WhQR_1EIK

    Then there's this post by Rawze:

    Rawze.com: Rawze's ISX Technical Discussion and more - Fixed Vane vs Variable Geometry Turbochargers...

    He claims that a VGT delete will kill mileage and has some sound technical arguments to back it up.

    So which turbo is best for fuel economy?
     
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  3. bad-luck

    bad-luck Road Train Member

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    Do you have a 11.1 or 12.7 60 series Detroit, or the 14.0
     
  4. rbrauns

    rbrauns Light Load Member

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    14L with EGR delete and I suspect a bad tune.
     
  5. bad-luck

    bad-luck Road Train Member

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    Ok, I know their are several different tunes for the 14L There was one that just used a band to keep the turbo vnt vanes from changing pitch. I am told that having a fixed vane turbo was the way to go. One thing I would not do with the 14L is turn up the hp. They can come apart
     
  6. benjamin260_6

    benjamin260_6 Medium Load Member

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    The VNT is the most efficient. It has The small A/R for fastest spool up and The big A/R for lots of flow and every A/R in between. The problem is they're programmed to work with the EGR system so they always run high drive pressure. Most guys who get rid of the EGR don't reprogram the VNT to work the way it should and it still runs with high drive pressure and kills the turbo.
     
    spsauerland Thanks this.
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