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[Ecotec] Forward facing OTR

Discussion in 'V6 Development And Modification' started by L36hunter, Jan 18, 2018.

  1. L36hunter

    L36hunter New Member

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    Hey guys. Ive been fiddling around with a grinder and welder to modify a VS ecotec inlet manifold to put the throttle at the front but realised that no VS models came with a forward facing intake.
    Is there anyone that makes or had made an OTR for the VS or will one off a VT/VX fit?

    Build first, plan later.
     
  2. harrop.senator

    harrop.senator Well-Known Member

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    May fit but honestly you've already got the tig out it may be less painful just to make one.
     
  3. harrop.senator

    harrop.senator Well-Known Member

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    My otr rocks up in a week for the Caprice can trial it on my vr but has no rad in it.
     
  4. EYY

    EYY Well-Known Member

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    They’re a decent intake manifold from the factory - I don’t know if you’ll gain much. You may even run into mixture distribution problems unless you run some kind of divider, but realistically you’d need to flow test to work it out.

    I’d still have a crack though. Never hurts to try something different.
     
  5. L36hunter

    L36hunter New Member

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    If it clears the rad support then i can chop and change things in front to clear. Im using a mig with alloy wire which is fine for the thick alloy of the manifold but sketchy with sheet but may have to
     
  6. L36hunter

    L36hunter New Member

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    This engine is an experimental project to try different things from the normal. I had spare manifolds lying around and thought id try something. If it works then great if not then try again
     
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  7. _R_J_K_

    _R_J_K_ Well-Known Member

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    Have a look at the US variants, they had a banana style manifold with what would be a forward facing throttle body in RWD config.
     
  8. L36hunter

    L36hunter New Member

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    Do you know what models they came in?
     
  9. _R_J_K_

    _R_J_K_ Well-Known Member

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    Any model (bar Holden) under Series II on this Wikipedia page - https://en.wikipedia.org/wiki/Buick_V6_engine

    AFAIK Holden are the only ones who used the plenum style intake, it is apparently advantageous somehow. People in the states have done the comparison, but I have no idea where the pages are. Maybe some Buick Grand National forums?

    TBH though, I don't think an OTR by itself will make much difference. My reasoning that most people think it does on an LS is because they're usually retuned at the same time, not in the sense that the OTR is some kind of magical power adder, just that the engine isn't running Holden's conservative tune any more and they happened to get an OTR at the same time.
     
    Last edited: Jan 21, 2018
  10. Sabbath'

    Sabbath' Redblock Jesus

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    This would be my biggest concern on a homemade manifold. The old Rajab or maybe Bresciani (really cant remember) intake manifolds for the RB30 that are of the same concept had a habit of the air racing to the back 2 cylinders and leaning out the rest on a couple of mates cars that had them.
     
  11. immortality

    immortality Moderator Staff Member

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    Something like this (the top half), which is tapered towards the rear of the manifold should solve the distribution problem...
    If I were to modify a ecotec intake I would machine down the plenum and then create a top that looks just like the below.
    [​IMG]

    I think the LS style OTR CAI works because it reduces the air flow path significantly. I don't think a later model OTR intake will fit as they are wider, many also hang down in front of the radiator of which there isn't much room on the VN-VS models unless you push the radiator back some how.
     
  12. EYY

    EYY Well-Known Member

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    Yeah on the vs an otr would need to go between the condenser and radiator after moving the radiator back. Which would mean restricted airflow, and if the aircon’s on it’d become a hot air intake and seriously hurt performance.

    There’s just no room between the rad support and bonnet unfortunately.
     
  13. L36hunter

    L36hunter New Member

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    That tapered design is how mine is. Its also 1" taller at the front giving larger volume/slow down air speed. Once its finished i need to plumb something up or im stuck with a pod hanging off the front.
    Going for a dyno run after to see the difference it makes compared to standard manifold.
     
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  14. _R_J_K_

    _R_J_K_ Well-Known Member

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    Are you going to use the stock T/B? Results won't necessarily be conclusive if you change the T/B size, not to mention they idle weird unless they've been tuned for it.

    Props for actually doing some testing though.
     
  15. L36hunter

    L36hunter New Member

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    Ive already had a dyno done with standard manifold with a 25mm bottom spacer and 69mm tb. Next dyno will be with modified manifold, 25mm spacer and 69mm tb then swap tb to a ls1 and do another run
     
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