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Thread: Two Level Boost

  1. #91
    Join Date
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    Quote Originally Posted by Nicely
    Looks as though its boost creep. Its taken a year, but I finally got a diagnosis off one of the SXOC Mods

    Disconnected the actuator arm from the turbo and tied the wastegate flap open. This should ensure that zero boost can build. Floored it in 5th and 6th over the usual peak power points where the problem usually occurs. Boost started building as the revs increased and peaks at 0.5 bar. With the wastegate fully open...

    This means that the wastegate isn't large enough to allow the boost pressure to escape quick enough to keep up with the flow of the exhaust.

    Three options:

    1. port the wastegate slightly larger. This is a documented and proved process.
    2. fit an external wastegate. Expensive and a ball ache.
    3. fit a smaller turbo elbow/dump pipe to increase the amount of back pressure and slow the flow.

    Now, Meddy had a near identical spec to me and never encountered boost creep. The only major difference in spec is that he still had the standard manifold. I've got to think about it, but I'm seriously considering fitting a standard main back on...

    To those with a tubular mani, you may well find you have the same problem once you try to boost over 1 bar if you have a T28BB...
    95% of the time I have no boost creep problems - running 1.1 bar, standard manifold with 3" off the turbo. The standard manifold might be the answer.
    What do you call a Rx7 with reliability, decent build quality and a better exhaust note? - a specR S15!

  2. #92
    Meddy Guest
    Sorry to drag this up here but Ive got a question for you Nicely. Before I strip the old turbo I just want to be certain it is actually faulty as at present Im not convinced there is anything wrong with it. I agree there is a bit of axial play, but I dont think this can be the bearings as theres no radial play which you would expect if the bearings had worn. I think the play might be just the bearing cartridge moving within the space allocated to it. They are held in place by a dowel pin which looking at the patents Ive got access to looks a pretty loose fit.

    So how much more play do you think there was in this unit?

    Ive asked a supplier for the tolerances allowable on axial movement but Im not sure how long a reply will take.

    Cheers.

  3. #93
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    I would agree that it appear the turbo was not at fault, and, although well used, is probably fine. In terms of the size of the impellers, the difference in play was 'noticeable'. That was how my engineer mate described it. I noticed more play, but wouldn't know whether or not is was vast.

    Incidentally, HKS EVC on its way....

  4. #94
    Meddy Guest
    Quote Originally Posted by Nicely
    I would agree that it appear the turbo was not at fault, and, although well used, is probably fine. In terms of the size of the impellers, the difference in play was 'noticeable'. That was how my engineer mate described it. I noticed more play, but wouldn't know whether or not is was vast.

    Incidentally, HKS EVC on its way....
    Best bet the EVC's are by far the best units IMHO.

    Incidentally if it turns out the tubby is ok how many pennies are you after for it. PM me please.

  5. #95
    S15R Guest
    my blitz id 3 is always been on auto, whats 0.9bar in Manual?

  6. #96
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    Well, in our colder climate, I have mine set to 62 and a gain of 5 and got a fairly consistant on 1 bar.

  7. #97
    S15R Guest
    Thanks Nicely, with the 62 and a gain of 5 setting, i assume its without the HKS actuator?

  8. #98
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    I believe that's what I set it to for the new turbo, so that's with an OEM actuator You can set it to a gain of 10 for quicker spooling, but just lower the boost figure slightly until you've seen the peak.

  9. #99
    S15R Guest
    Mines set on auto at 0.9bar with GAIN on 7 and it never reach 0.9bar peak was 0.82bar this morning...

    thats why i wanted to try out the Manual Setting, i might play around with it tonight.

  10. #100
    S15R Guest
    quick question,

    I've connect the vacuum tube to the pipe that goes to the BOV, if thats ok?
    i was told to use the hose to the FPR but im also worried about the plastic tube that blitz provided will melt

    also, i'd like to know where is the stock boost gauge sensor connected to?

    Thanks

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