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340 headers VF2

Discussion in 'VF Holden Commodore (2013 - 2017)' started by Nico36, Mar 8, 2018.

  1. LS1SS

    LS1SS Active Member

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    Finally found some one that has 200 cel cats to fit HSV headers off the shelf,Extracted Performance Exhausts in Vic,03 9794 6334,very helpful and informative guys to talk to,to make fit cut off cone on mid section and weld on new flange and bolt together,it’s the way I’m going.
     
  2. monstar

    monstar Naturally as-pirated

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    Is yours a 6.0 or 6.2? You can get similar piece ready to fit for $550, thing is with this setup you lose the stock tune / wty which is helluva price to pay to put out engine warning. Then of course there's a remote chance get pulled up coz it stinks.
    VFII cat with modded downpipe is less risk.
     
  3. LS1SS

    LS1SS Active Member

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    Mine is a 6.2,I didn’t know cats stink if you just change just the cats only,then why do long tubes with cats don’t stink? The path I was heading for was to cut both necks off the VFll std cats widen the mouths a tad weld a flange directly to the cat one end then get a nice 2.1/2 mandrel bend to the other end to HSV headers,hows that sound? I have the back sensors neutered already,once I get it figured out it’s off for a tune,if it doesn’t work it’s Hurricane 4-1s.
     
  4. monstar

    monstar Naturally as-pirated

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    I was being glib, meant that you won't pass emissions with cat swap vs using the original cat. Will stink more than before, about as much as any near stock engine with racing cats though.
    Very good, but 2" mandrel is probably better balance of torque and HP.
    Fair enough just saying there is a reasonable chance you do not need to use the piggy backs or change the tune and stay legit in the interim with the VFII cats.
     
  5. PeteSS

    PeteSS Active Member

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    I assumed the HSV LSA's use 200cel cats. Can't smell a thing. i think it's when you go to 100cel cats that the nauseating smell starts

    Mine has 100cel cats, along with the cam you can smell the car before you hear or see it...
     
  6. lmoengnr

    lmoengnr Well-Known Member

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    I think it depends on the size of the cats, where they're positioned, and the tune.
     
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  7. LS1SS

    LS1SS Active Member

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    Monstar you recommend going 2inch for the mandrel bend from the HSV header to VFll cat,I thought you would need at least 2 1/2 for that pipe to get the flow going,why 2inch? As you can see I’m not a pipe master just trying to master it.
     
  8. MY17DIR

    MY17DIR Active Member

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    Do you have any pics of their setup?
     
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  9. dessy

    dessy Member

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    I am interested too, they don't appear to have an active website.
     
  10. LS1SS

    LS1SS Active Member

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    Contact Andrew at Extracted Performance,these are the fotos he sent me re cat enquiry,they look good,evidently you can get 3inch or 2 1/2 dia pipe.Im looking at these but trying some thing out first,I have cut the pipes off my std cats and getting pipes made up and see how it goes,shal take fotos if it works well.
     

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  11. dessy

    dessy Member

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    Cheers LS1SS
     
  12. monstar

    monstar Naturally as-pirated

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    ‘Bullet cats’ by themselves are $125-$150 each x2 so yeah around $550 the pair ready-made is OK.
    558FAF46-F5F9-4518-92F4-306840CFF701.jpeg
    Dimensionally if you have the 340 set with 2 1/2” outlet at the merge then may as well stick to a 6100+ top end tuning target for max HP. 3” downpipe is just too big for this engine.
    Otherwise the 2.25” outlet of R8 is better TQ/HP balance for everyday, matched with 2” downpipe gets you more torque 95% of the driving time.
    The main thing is space restriction longitudinally to the stock catback flange location of course. Ideally you want the length of downpipe 9” measured along the centreline before entry to cat. The HM (left), HSV (right) are easy cos bolt-on ready-made but downpipe is way short:
    171051CD-DFA4-4905-A645-18C264CF6BEF.jpeg 746CBCBF-15C2-4374-A4A6-060FC3411B83.jpeg
    So grafting the required mandrel bend moves HSV cat all the way rear, then just flange your cat’s butt :eek:
    As you’re taking a hacksaw to it could do same with Holden VF cats (below), doesn’t matter.
    3B5315F2-04F8-41A6-BDFE-29C5F51E4915.jpeg
    Can hardly see down there, stainless won’t stay shiny at cat temps, silly to waste money on shiny branded stuff that is technically incorrect.
    Deng Xiaoping famously said that it doesn't matter if a cat is black or white so long as it catches mice, here doesn’t matter which (bullet) cat as long as it has a 200+ cpi steel substrate.
    Short fat barrel cat is better than long skinny for fit and theory, possibly not emissions.
    Here is what I did with proper length mandrel downpipe:
    C4257363-81EA-4652-8D08-14EAE8964413.jpeg 409688B5-CA76-4A02-9F4D-51090A6C443F.jpeg
    CB9BEFAE-D1A2-4DE9-B2B7-344CAB7A9E7E.jpeg 24035745-75DC-47E5-A789-D8428B78832D.jpeg
     
  13. LS1SS

    LS1SS Active Member

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    That is a very good layman’s terms about cats Monstar,I’m experimenting with std VFll cats I took off my log manifold,I cut both pipes off the cats,I’m going to weld cat directly to plate weld another plate to my 2 1/2 R8 mid to get rid of cone flange then on inlet as you stated 2inch mandrel from cat to HSV headers and see if it all fits nice,just doing it as an easy cost exercise for blokes that want 400s and remain inside smog laws,as I go I shall take fotos.You can’t get HM cats off the shelf any more as they are now insolvent.
     
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  14. VF_CalaisV

    VF_CalaisV New Member

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    That's exactly what I am considering doing..
    I'm just waiting to find out which cats actually flow best, either the VE-VF S1 or the VF ii. By looks you would think the earlier ones since they are larger... But the VFii cats don't seem to have lost power and the smaller size helps get nicer bend sections in before the standard CAT back location.
    Actually it looks like the VFii V8 CATs might even be the same as the LFX V6 CATs?? Does anyone know?
     
    Last edited: Apr 13, 2018
  15. Nico36

    Nico36 Member

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    Well if anyone was interested in the update my redline ended up making 385kw with VCM OTR, 340 headers and 2.5" centre section and tune so pretty happy with that. Sounds great with bimodal fuse gone.
     
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  16. lmoengnr

    lmoengnr Well-Known Member

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    You have an extreme example of LS3's!
     
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  17. Nico36

    Nico36 Member

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    I wish it was louder, but I think I am in the happy medium where it is a great note, decently loud with no drone whatsoever. I think if I start looking at other options to make it louder it will be less productive. Or maybe now a cam....... ;)
     
    Last edited: Jul 11, 2018
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  18. 426Cuda

    426Cuda SUBLIME!

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    Great result. Without the WP price too!
     
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  19. MY17DIR

    MY17DIR Active Member

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    Awesome! Did you use the HSV cats aswell or go with 200 cell hiflow replacement? Apparently some good gains to be had in replacing the HSV cats too.
     
  20. .05

    .05 Member

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    most of the hsv headers i see with cats are sold advertised with no size of exit flange pipe size, 340kw are 2 1/2inch what size are the other hsv header pipes 2 1/4 inch ?
    is there any difference between 325kw hsv headers to 340kw hsv headers power wise
    everyone seems to only talk of the larger 340 ones
    for street traffic light drags would i notice much difference between the two
    or is it just you can pick them up for the the same price, might as well get the 340kw ones
     

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