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VT V6 head work gains?

Discussion in 'V6 Development And Modification' started by TI3VOM, May 28, 2010.

  1. TI3VOM

    TI3VOM Active Member

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    Hi there guys and gals I went to get a price for my heads to get ported and polished+shaved the guy that I spoke to said that it's not worth the money and there will be not much of a gain and the other bloke there said that the manifold would not match up after shaving the heads.

    So my question is who has had there heads Ported polished and shaved and what gains have you yielded plus did your intake manifold match up ok and if not what did you do to fix it.
    Cheers Glenn.
     
  2. chargedvx6

    chargedvx6 Active Member

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    The heads will only perform as well as the next restriction in the chain will allow. If you have a F/I engine that rule becomes a little less important.
     
  3. TI3VOM

    TI3VOM Active Member

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    Has anybody done it and had gains? I am asking this question as I know there will be another restriction somewhere along the lines within the engine. All I need is twin cats and I'll have all the bolt on mods that I can get for a VT V6 to breath so now I need to open up the engine to see more gains.
     
    Last edited: May 29, 2010
  4. bandidoben

    bandidoben New Member

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    doing that on its own will do F all mate unless you upgrade the cam or rockers. id be doing these things first then the head work.
     
  5. 0081

    0081 New Member

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    I think you will find there are gains to be had but the costs to carry out this mod will be a fair bit, as you are not up only for the head work but all the head bolts, gaskets and sealent to refit the heads.

    I would look at cam and or rockers, valave springs and a double row timing chain first.
     
  6. Dr Goggles

    Dr Goggles New Member

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    if you shave the heads you will have a poorer fit with the intake manifold, as the inlet face will move down and away from the manifold. You'll get bigger gains with a bigger or twin throttle body. A port job on it's own won't give you much....a shave on it's own will give you grief.......
     
  7. Tsunamix

    Tsunamix Active Member

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    v6 Heads are over-ported from the factory. You see the ports are shaped around the american bunch of bananas manifold, and the junction between head and manifold is the area in which the air stream turns from a vertical up and down type flow, into the back of the valve.

    In essence - the port doesn't cut straight across the designed air path, but at a diagonal.

    Holden australia re-worked the Inlet manifold to build torque - quite successfully I might add. No Alloytec has ever had the torque of the ecotech.

    In the re-work, the existing port ended up too big for new air path. which as long as you don't machine out the manifold, doesn't affect airflow much, and seems to impart a bit of tumble which helps atomisation at the injector.

    If you machine out the manifold to match the port, you end up with a dirty big chamber at the end of the manifold runner, that is almost twice the cross sectional area of the inlet runner. What this does is slow down the airflow, reducing torque.

    From what I have been able to test, there actually looks to be some gains available (as much as 25kw) from welding up the ports in the head, and grinding them back to match the manifold. It seems if you add some material to the floor of the port in the head, flattening out the curve in the floor, and match it up to the inlet runner, you get a much much better flow velocity.

    I've been doing some flow bench work and at 26inHG the flow figure goes from 121 CFM up to 138CFM and airspeed 88% of inlet to 104% on inlet - inother words flow is increasing and air is accelerating as it travels down the runner instead of slowing.

    But atomisation is reduced due to less tumble. Careful shaping may see me able to add some swirl back in though. Lots more work to do yet.
     
  8. TI3VOM

    TI3VOM Active Member

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    Cheers Tsunamix that's a lot of good info there I will speak to a few guys that deal with heads and see what they can do or suggest.
     
  9. TI3VOM

    TI3VOM Active Member

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    I already have RR's on it and I am looking at a cam upgrade at the moment
     
  10. TI3VOM

    TI3VOM Active Member

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    Right at this moment I am comparing prices between the manifold spacer, plenum spacer, larger throttle body as opposed to a twin throttle body setup.
    Either way by the time I get the heads done if I do now I would have a larger T/B+more or a twin T/B setup.
     
  11. chargedvx6

    chargedvx6 Active Member

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    I wouldn't waste money on a larger throttle body, MAF or even twin throtts. They all are a placebo effect really. The reason I say that is that they will all only be able to flow as much as the next restriction like I said earlier. Your plenum runners and head intake ports are only so big.

    An efficiently performing engine will always have a balanced intake path rather than a big **** off TB and MAF all going into the standard plenum runners. By the way the MAF will stop reading at a certain amount of airflow anyways regardless of how big it goes due to the element having a limited range.
     
  12. one_and_only2004

    one_and_only2004 Turbo L98 FTW

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    If you're wanting to go down the heads path, expect to spend roughly $4000 to get an awesome set, plus a decent cam to make use of them. Mine are flowed to 650HP, mind you I only replaced the heads because I did every other possible thing to it.

    I personally know Jack brothers in brisbane do an awesome - but pricey - job on ecotec heads.
     
  13. acarmody

    acarmody Donati..Whoa Green

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    How pricey? And I believe I've heard of Jack Bros. before, expensive but great work right?
     
  14. one_and_only2004

    one_and_only2004 Turbo L98 FTW

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    Correct, These $4000 Stage 4 spec heads are brought to you by Jack Bros. Flowed to 650HP. Larger valves are physically impossible - without a lot of work being done.
    [​IMG]
     
  15. TI3VOM

    TI3VOM Active Member

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    I never once said that I was going to get a larger MAF they are a restriction at around 180RWKW or something close to that so I wont bother I have seen someone gain from getting a larger throttle body + there plenum chamber ported.
    If I was to get the heads done I would also get the intake manifold done at the same time I would be stupid not to as I will save money doing it that way.

    What would be the next restriction if I have an aftermarket CAI, K&N panel filter, High ratio RR's, Pacemaker extractors, twin cats and custom Y piece, 2.5" cat back exhaust. Apart from heads, intake manifold, cam.
     
  16. TI3VOM

    TI3VOM Active Member

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    one_and_only2004 do you have specs on those heads.

    You can get these I'm not sure that they're better:

    MRC Performance have these aluminium heads to suit your Holden Ecotec V6.
    Not only do these new heads address every shortcoming of the factory iron heads, they are one of the single largest mods you can do to improve the performance of your vehicle.
    Benefits include:
    · 16 pounds of weight savings, improving vehicle weight balance, launching, handling, fuel economy and braking
    Increase flow provides large HP gains in every application and better engine efficiency for improved economy
    · Aluminium allows higher boost and/or more compression with the same octane fuel
    · 56cc chambers increase compression
    · 148cc intake runners, 58cc exhaust
    · Reinforcements to prevent flexing under high boost applications
    · Extra material for custom port work
    · Sturdy rocker stands which remove potential rocker arm movement under high loads
    · Custom designed to allow the addition of extra head bolts on top and below cylinders
    · 1.96 intake 1.57 exhaust valves
    · Surface finish of 40 ra ensures perfect sealing with any head gaskets

    Complete heads - Assembled and ready to bolt on. (Complete with 130# springs, REV valves, hardened seats, guides, valve seals, retainers, keepers. Setup for up to .600 lift)
    Weight: 4.00 kg
    Price: $ 3,300.00
     
  17. one_and_only2004

    one_and_only2004 Turbo L98 FTW

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    You haven't got much left, Half your breathing in is setup, your breathing out looks good

    MAF, throttle body, intake manifold and heads are what's choking the motor.
     
  18. TI3VOM

    TI3VOM Active Member

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    Yeah I know that's why I was asking the original question cause when the guy I spoke to said there will be no real gain I wanted to find out from people that may have done before I don't care if there are no KW/HP gains on a dyno just as long as there are gains while actually driving.

    Also the guy that I spoke to said that you can not get bigger valves for the ecotec heads cause they are as big as they can be does this sound right?
     
    Last edited: May 31, 2010
  19. one_and_only2004

    one_and_only2004 Turbo L98 FTW

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    Sounds like this guy is an idiot who doesn't know what's going on. I have seen the same set of heads that i've got on an NA application, and it was nothing to sneeze at - very fun to drive.
     
  20. chargedvx6

    chargedvx6 Active Member

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    $4000 on Ecotec heads? Bit rich for my liking there. That's the same price as a built bottom end which would actually give you more power with upped comp ratio etc etc.

    Yeah i vouch for ecotec heads happily taking bigger valves. I run 1.90" intake and 1.57" exhaust valves with all the same hardware as these ones. INTENSE-Racing.com: INTENSE™ Stage 4 CNC Cylinder Heads (pair)

    Sorta shows that $4g is a waste on heads. You can get ZZP alloy heads for around $3000 landed from the states pr these Intense racing iron heads for a bit less. there are also a few good shops around in AUS that are more than competent. After all good head shops apply a formula to the ports and replicate thate as closely as possible from one port to the next.
     

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