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Are 325KW headers an upgrade?

Discussion in 'VF Holden Commodore (2013 - 2017)' started by lordsnipe, Jan 14, 2019.

  1. lordsnipe

    lordsnipe New Member

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    Hi all, this is taken from Redbook:

    LS3 340
    340KW @ 6100rpm
    570Nm @ 4650rpm

    LS3 325
    325KW @ 6000rpm
    550Nm @ 4600rpm

    LS3 VF
    304KW @ 6000rpm
    570Nm @ 4400rpm

    The 325KW configuration is down 20Nm at 200rpm higher in torque vs 340 and the stock VF LS3 config. I know peak power/torque isn't everything but hard to gauge without graphs to see area under the curves.
     
  2. dimetime

    dimetime Active Member

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    i believe the headers are the same for the hsvs, the collectors are slightly different but nearly identical, i think the main power difference is either the airbox or just the tune.
    the vf2 ls3 has the standard cast iron headers found on most the ls engines from the l98 and ls2 and the airbox is also a basic design and very restrictive.
     
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  3. lordsnipe

    lordsnipe New Member

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    The HSV 340KW headers and cats have a 2.5" outlet I believe, compared to 2.25".

    The bimodal airbox has a flap which can draw additional air from the bottom of the intake tract, but the box and filter appears to be the same as VE/VF models.
     
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  4. VS 5.0

    VS 5.0 Well-Known Member

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    I also believe this to be true.

    I'm sure I have seen a video from @426Cuda talking about this.
     
  5. lmoengnr

    lmoengnr Well-Known Member

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    They should be a slight upgrade, if you can get them fairly cheaply, and then upgrade the cats to a pair of high flow versions.
    I have a set packed away in the workshop. I thought about fitting them to the Magnum, modifying the L/H set by grinding the header/cat flange to clear the oil/coolant heat exchanger, but decided to go aftermarket in the future...
     
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  6. lordsnipe

    lordsnipe New Member

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    I've seen headers and cats in the 350ish range .. is that a decent price?
     
  7. lmoengnr

    lmoengnr Well-Known Member

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    'Decent price' is up to you to decide... I think it's too much, as the cats are basically worthless, but that's only my opinion.
     
  8. abuch47

    abuch47 Active Member

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    Someone in geelong sells them for $250. $500 for whole system.

    I found a 340kw maloo on gummy with aftermarket exhaust, asked the guy for the old system and paid $300 for a rust bucket but they never come up in adelaide so took it
     
  9. lordsnipe

    lordsnipe New Member

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    Thanks all, I've got a 2.5" midsection on the way, will probably put that on first and go from there.
     
  10. 426Cuda

    426Cuda SUBLIME!

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    The 325 headers are definitely an upgrade over the stock manifolds. Especially with high flow cats as Imoengnr said.
     
    Last edited: Jan 15, 2019
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  11. abuch47

    abuch47 Active Member

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    who does high flow converters that bolt between the hsv system?
     
  12. abuch47

    abuch47 Active Member

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    The 340 is a 2.5inch outlet.

    also what the difference between 317 and 325?
     
  13. 426Cuda

    426Cuda SUBLIME!

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    No difference in the headers. They are the same.
     
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  14. 426Cuda

    426Cuda SUBLIME!

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    I bought a set of bullet style cats and got flanges welded up to fit.
     
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  15. lmoengnr

    lmoengnr Well-Known Member

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    The mid section. 317kw version has the same mid section as an SS/SSV/Redline.
    325kw version has the true 2.5" mid section.
     
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  16. panhead

    panhead Well-Known Member

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    Everybody....


    At least everybody in the exhaust game who knows their business can knock up a set.




    .
     
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  17. rognvald261

    rognvald261 Member

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    There are a few threads here detailing the optimal downpipe from the HSV headers and cat dimensions, price, etc., to the stock catback flange.
    Worth also looking at the argument for relocating that catback flange in favour of a proper tuned secondary / cat position (also available via search).
    Sourcing the 4” spun steel Chinese barrel cats is easy, the dimension and form of the downpipe from header merge flange extending pre-cat (secondary) depends whether your tuning target is skewed to HP vs torque.
    Be careful bolting on high HP bits requiring fine tuning, there’s always a trade-off, so without a custom tune mods like this may result in poor overall performance.
     
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  18. blackve76

    blackve76 Well-Known Member

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    Get about $40/50 per cat at scrap joints (ring around).

    Personally for the effort of changing etc look at a good set of headers, if $$$ a concern some wreckers have heaps of crashed commodores with quality systems for reasonable $$$
     
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  19. abuch47

    abuch47 Active Member

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    I have read through those and picked up the full hsv system to sort me out for the mean time. According to those the try y (4-2-1) design was better than 4-1 but the stock collector and cat position is flawed. He who shall not be named believed 180° equal length headers were the best for the LS firing order and he has publicly stated $6k for a system from himself.

    I love the idea of 180 degrees but finding someone who can make that and perfect everything else would be hard pressed and I'd probably ask the pirate.
     
  20. rognvald261

    rognvald261 Member

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    Just saying the importance of the bit between end of primaries and catback is worth reviewing.
    Dirk is on FaceBook BTW, has a group called All Motor Legal.
     
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