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308 performance heads

Discussion in 'V8 Development and Modification' started by NZR8, Feb 10, 2019.

  1. NZR8

    NZR8 New Member

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    Hey
    I’m slowly building up a red hq 308 for my vb commodore have been looking into whether to go for vn heads or get the hq heads ported, I’m only wanting a decent accelerating street car nothing too crazy maybe 350hp at the flywheel.

    I’m wondering what people’s thoughts are on these heads I’ve been looking at I was think along the lines of the test #3 at the bottom which I’m guessing is their custom grind cam with these heads.

    http://www.heads.co.nz/308heads.html

    Thanks
     
  2. EYY

    EYY Well-Known Member

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    For that sort of money you’re much better off starting with VN heads. Mind you - I just looked at the price and didn’t read much into that page.

    Vn heads are far superior to early heads from the factory, and they take very little work to get them flowing plenty.
     
  3. Smitty

    Smitty Well-Known Member

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    bwahahaha..... urban myth
    the only thing they have as stock standard over the earlys is a slightly
    better exhaust flow ... and a nicely arranged equidistant exhaust manifold :)
     
  4. EYY

    EYY Well-Known Member

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    Don’t understand mate.. VN heads start with larger valves and ports from the factory. Put equal money and porting time into vn’s vs early heads and vn’s will come out on top. Holden wouldn’t have done all that r&d just for the sake of having a head that looked different.

    Have you compared them side by side? I have, and there’s no way old 308 heads flow anywhere near as much as vn’s.

    I have ported large valve early heads on the 308 in my hj. It’s a stump puller but power tapers off quite quickly approaching 4500rpm.

    I also have a 304 in my vs with factory manifold but crane 268 (308 has a crow 666) and it has slightly less bottom end but much more midrange top end and would have more power overall. Even with the considerably smaller cam.
     
    Last edited: Feb 11, 2019
  5. delcowizzid

    delcowizzid on holiday

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    The dyno numbers they are posting are around where stock vn heads go with a small cam
     
  6. NZR8

    NZR8 New Member

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    Yeah I figured the same power could be had with standard vn heads but with the cost factored in if buying vn heads which are around $300 and the price of overhauling them so everything is new like the 308 heads must still end up at around $1000?all up And then have to buy new intake to suit so the price is similar? and I’m guessing I would more then likely need to swap to later model k frame with vn heads for header clearance?
    But then have a lot more potential for further mods yeah?
     
  7. delcowizzid

    delcowizzid on holiday

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    Vn heads flow enough for 420-450hp a quick multi angle valve job a clean up of the dags in the bowls a resurface of the valve faces and some springs they be good to go headers are different and inlet and the cam is different the lobes are in a different order for the exhaust port swap that moves the ports apart to stop the hot spot in the middle of the heads.stock headers and pacemaker 4-2-1 should still fit with stock kframe and rack
     

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