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Thread: Two Level Boost

  1. #21
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    If it was boost cut, why does boost surge up to 1.3+ bar in 6th when it passes through the hesitation if I don't back off?

    Having run and tuned two SR20DET engines for three years, I'm fully aware of what boost/fuel cut feels like, having peeled my head off the windscreen many times after hitting it. It won't hit cut until somewhere around 1.3 bar in the current sub 10 degree UK climate and with the existing fuel and air ratio setup. I have an Emanage fitted, so could raise the cut limit if I wanted, however, I see it as a warning and heed it.

    The hesitation I'm detecting is just that. You can feel it during boost and the boost continues after it.

    All hoses clamps have been checked. Wastegate opens and shuts fine. Controller ruled out. Actuator ruled out. The only thing which hasn't been checked, as far as I know, is the cooler itself. Think I'm going to have to pressure test...

  2. #22
    Purpleline Guest
    understood but your styptom just like many other GTT here...not all of them have this problem...some are ok but some are not ..chipped ECU or wise down gain fix the problem ...

  3. #23
    Brad Guest
    Thats strange the Blitz manual saying a gain of 20 too, tuning place and some dyno time definately show 5 is the right ball-park figure to be at with the stock actuator and turbo.

    Brad.

  4. #24
    yewei Guest
    hey i have a problem with my boost setting? my fren is makin more hp with lower % of boost than i am? can u people share with me ur boost setting? my mods r pretty simple, apexi air intake, rsm, custom made exhaust system of 2.5" down pipe, 3" silencer then its all the way 3" till the 3" jun muffler. its kinda loud too? too free flow? help?

  5. #25
    KSW Guest
    Hi nicely, think im having the same problem as you here, did you ever get to the bottom of it?

    I just put a boost gauge in my s15 and its showing boost holding steady at 1 bar (which it is set to) up to around 4000 rpm under floored acceleration in low gears and then shooting over up to around 1.3 at higher revs.

    I have a stock turbo with intercooler, fower fc and the apexi actuator boost kit (no ebc)
    anyway ill go thru the car on the weekend and search for leaks in the piping. im wondering if a sdc idIII would help the situation.

    cheers

  6. #26
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    No, I haven't

    I've got a replacement T28BB with only 3k miles on it to change over (when I'm motivated). My current turbo has got noticably more play than the newly new one. I'm hoping this is the reason. Run out of ideas as to what else it could be.

  7. #27
    KSW Guest
    ok thanks anyway. i can imagine how frustrating this would be for you having this problem going on for a while. my understanding of turbos is pretty limited, im wondering if you think a boost leak in say the intercooler piping could cause a boost spike like this or do you think it would work the other way around and the car would struggle to produce enough boost?
    the only thing i can think of at the moment is maybe its my BOV leaking cause i havnt had it that long and its a pretty cheap plumback, or maybe one of my hose clamps is sealing the ic piping well enough up to a certain pressuse but leaking at extremely high pressures.
    cheers

  8. #28
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    It depends on the size of the leak. If its a big leak, you'll get no boost. If its a small leak, it will leak up to a certain level, then the boost would be enough to overcome the leak and spool the turbo. Whether or not it would be to the degree that we are getting, I don't know. My investigations and instinct tell me its not a boost leak... However, I am wrong on occaisions...

  9. #29
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    I found a very interesting article on Autospeed.

    http://autospeed.drive.com.au/cms/A_...popularArticle

    It details mid-range boost spiking caused by better flow. They explain that the in-built ECU boost control on many car is quite primitive and cannot work quick enough to cope with the very quick boost increases caused by better flow. This results in the turbo spooling dramatically before it can be brought under control (spiking). They recommend fitting a boost relief valve in a bypass circuit around the boost solenoid, and found it had very good results.

    Now that is for the factory solenoid, not a boost controller solenoid (which should be able to manage this spiking). I'm thinking that maybe it can't? Might be worth trying what it suggests...

  10. #30
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    I think it would be worth a shot

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