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balance tube

in General Tech Discussion 11 years ago

  • Re: balance tube

    by » 11 years ago

    Greg,

    It certainly sounds like the turbo is dumping boost. That is still a puzzler though because the larger balance tube in no way raises or lowers manifold pressure. It just equalizes existing pressures more efficiently between manifolds. Since it doesn't change manifold pressure, it shouldn't change airbox pressure and thereby shouldn't effect boost. Does the TCU measure manifold pressure or airbox pressure? If it monitors airbox pressure for regulating the boost, the TCU would not know the balance tube had been changed.

    The mystery deepens.

    Bill.
      
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  • Re: balance tube

    by » 11 years ago

    Bill
    Mates 912 ran just as bad would not rev past 4000 I reckon where I welded the tails in must be diverting some of the charge away from the back intake ports swapped everything back and the912 ran OK I have now lost interest in trying again and will now try and find some more manifolds as I don't think I can weld the plugs back in good enough any way it filled the day in
    Greg
      
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  • Re: balance tube

    by » 11 years ago

    Greg
    I have a 914 and have been tempted by this idea. I agree with you and Bill, it doesn't make any sense that the 914 shouldn't work with this mod unless, as you suggest, the way you have welded the tails is somehow upsetting the flow. Can you post a photo of your modified manifolds so I don't make the same mistake?
    If you need new manifolds I was offered a set by this guy rotaxteile@yahoo.de he wanted 380 US$.
    Mike G
      
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  • Re: balance tube

    by » 11 years ago

    Hi Mike
    I have swapped my manifolds with a fellow from interstate and he was going to use them on a fuel inject 912 and he gave me some off a another engine to get me out of trouble so I hope sooner or later a wrecked motor will turn up so I can return the favour I cant send a picture as they have gone but I welded the tails so they faced straight across the engine just in front of the cdi units and connected them with some fuel hose but in the end I think I may have been loosing charge to the back cylinders now I my mates tell me I should have left well enough alone
    If you can get some manifolds it may be worth a try putting the tails where the balance pipe is now, sorry I cant be more help
    Greg
    Thank you said by: Mike Goodrich
      
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  • Re: balance tube

    by » 11 years ago

    Bill,

    I'm quite interested in this mod and now thinking about the parts gathering process. What alloy aluminum did you use? I don't want to get something that can't be properly welded. I will have to get a professional to do that part.

    Thanks,
    Alan
      
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