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Thread: VGT Tables for E98

  1. #1
    Senior Member SV8346's Avatar
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    Default VGT Tables for E98

    So what are our chances of being able to adjust the Turbo Target Vane Position tables in OS 55491998(DSP4 - 65491998). Seem to be able to adjust these tables in nearly every other OS that uses them but the poor little E98 gets forgotten about and pushed into the back ground when it comes to developments.
    2016 RG Colorado 2.8TD

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    Lifetime Member Tre-Cool's Avatar
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    i've played with in hpt, majority of the time it's still hit/miss for changes. (could be hpt's fault) but for a stock turbo setup probably not needed.

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    Forum tyhee Site Admin GMPX's Avatar
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    I understand it appears that nothing is happening with the E98 but it isn't the case, in the last three months we've had to add DSP4 conversion patches for several 2016 & 2017 US OS's, support for new OS's 55504430, 55500370 & 55488112. Fixed some speed limiter cal errors on early OS's too.
    Unfortunately the Holden OS is a bit of a bugger to work with and unfortunately I never find the time to find those tables between managing all the other mapping, sorry, trying to make it happen. And to add to what Tre-Cool said, others have said the same thing, modifying them in HPT for example doesn't tend to get the results anyway.


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    Senior Member SV8346's Avatar
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    Yeah but for some reason i am finding that at full noise turbo cant seem to keep up or something weird? Desired boost and max allowed boost is set to 340kpa which i believe is above the Map sensors control anyway yet at full throttle at around 3000rpm the boost drops away slowly down to 270kPa yet the vane % is still showing 40% which is telling me that the turbo is still being restricted by 40%? Would this be correct?
    2016 RG Colorado 2.8TD

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    Lifetime Member Tre-Cool's Avatar
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    100% is the vanes are fully closed (max response, spool up)
    0% is fully open (bypass, max flow out rear etc)

    I think these turbo's just dont have the flow capability for pushing that much air at those rpm's. Your not alone with the issue.

  6. #6
    Senior Member SV8346's Avatar
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    Quote Originally Posted by Tre-Cool View Post
    100% is the vanes are fully closed (max response, spool up)
    0% is fully open (bypass, max flow out rear etc)

    I think these turbo's just dont have the flow capability for pushing that much air at those rpm's. Your not alone with the issue.
    So yeah when its reading 40%, is still 40% restricted? Is that not correct?
    2016 RG Colorado 2.8TD

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    Quote Originally Posted by SV8346 View Post
    So yeah when its reading 40%, is still 40% restricted? Is that not correct?
    wouldn't it be fair to say it is restricting the vain trying to get the boost target you are requesting?

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    Senior Member SV8346's Avatar
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    Quote Originally Posted by HOWQUICK View Post
    wouldn't it be fair to say it is restricting the vain trying to get the boost target you are requesting?
    From what i have read the standard OEM program max's out at 40%. No matter what you do engine wise it will still be 40% restricted, it wont allow the turbo to use the remaining 40% of the turbo's flow, this is why i am trying to edit the vane table to be able to use that 40% as well.
    2016 RG Colorado 2.8TD

  9. #9
    Lifetime Member Tre-Cool's Avatar
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    following on from what howquick is saying, you really need to think of the vane as a bleed off valve more than anything. if it can't hit your boost pressure with a 40% closed vane what makes you think it'll do it at 60%. all your doing is just spinning the blade faster & pushing the turbo cartridge past it's efficiency range = more hot air. hot air is less dense.

    closed vanes slow down the gases out of the motor/exhaust as it's forcing it to turn the turbine. Technically you really want the vanes to be open more while keeping boost responsive, this in turn helps to drop egt's & increases efficiency.

    The highest i have ever seen is about 90% for vane closed & 5% for fully open on a DPF equipped colorado when doing regen. Dpf regen process opens the vane all the open to bypass as much boost as possible (often going into vacuum, then switches to a really late injection timing to put heat into the exhaust & not the motor.

  10. #10
    Senior Member SV8346's Avatar
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    Ok, so let me try to get my head around all of this,
    At 100% its fully closed therefor creating the most restriction or creating faster airflow for low amounts of air into the exhaust housing?
    At 0% its fully open therefor allowing more air into the exhaust housing and in turn allowing the turbo to spin harder if the exhaust gas is sufficient and then which in turn pushes more air into the engine?

    So, if i was at 3000rpm and at 40% vane and allowing 60% of the air into the turbo to create 30psi of boost. Then if i maintained the same rpm yet i now allowed the turbo to open up to 10% allowing more air into the exhaust turbine therefor spooling the turbo harder and in turn creating more boost? Is that not correct?
    2016 RG Colorado 2.8TD

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