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Thread: 997 Turbo? Variable Turbine Geometry?

  1. #1
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    997 Turbo? Variable Turbine Geometry?

    Porsche is celebrating the 100th anniversary of the invention of the turbocharger (November 16) by announcing a new turbo setup that will launch with its next-gen 911 Turbo. Variable Turbine Geometry (VTG) continuously adjusts the angle of the compressor’s turbine blades to direct exhaust gases on to the turbine wheel optimally, increasing torque at low engine speeds, widening the torque range and increasing engine output at high speeds. According to Porsche, the high exhaust-gas temps had made such systems a guaranteed meltdown-maker for gas engines (turbodiesels have used variable blades since the early 1990s), but the company’s new version applies materials from the aerospace industry to withstand the 1800-degree temperatures generated. If it all works as expected (and why should it not) the upcoming 911 Turbo will gain some driving refinement over the click-click-(boom!) response of previous models.
    Anybody can confirm this? Any release-dates for media-site pics?

    http://www.autoweek.nl/newsdisp.php?cache=no&ID=4202
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    only from magazines... nothing officially as far I know...

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    It would be cool if the implemented Variable Turbine Geometry (VTG) to the new 997 Turbo. But I've read that the 996 Turbo doesn't suffer from turbo lag and thus no click-click-(boom!) as stated in the article.
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    I read in some History of the Turbo somewhere or other (may have been GermanCarFans) that every time Porsche release a new Turbo, there is some new 'ground-breaking' system applied, and this variable-turbo was mentionned in that too. Seeing that picture for the first time though, although looks a bit PS.
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    Quote Originally Posted by RazaBlade
    I read in some History of the Turbo somewhere or other (may have been GermanCarFans) that every time Porsche release a new Turbo, there is some new 'ground-breaking' system applied, and this variable-turbo was mentionned in that too. Seeing that picture for the first time though, although looks a bit PS.
    id have to say thats true. the 911 turbo was the first street car to be turbocharged. In the pic, the disguise bumper looks good on the new turbo. although a striking set of rims would be nice

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    I dont know about the VGT too much, but I know the body kit looks friggin awesome
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    kool, i've always wanted to see VGT in a gasoline engine(only seen it in diesel trucks), wonder if it will really make the turbo boost up faster.
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    This is a different system than VATN (Variable Area Turbine Nozzle).

    The core features of the VTG system are the variable turbine blades guiding the flow of exhaust gas from the engine in exactly the direction required on to the turbine wheel of the exhaust gas turbocharger. The principle of variable turbine geometry thus combines the benefits of a small and large exhaust gas turbocharger all in one – a combination ensuring both very good response and high torque at low engine speeds as well as superior output and high performance at high speeds. And the supreme level of torque is now maintained consistently throughout a much wider speed range.
    Some turbochargers utilise a set of vanes in the exhaust housing to maintain a constant gas velocity across the turbine, the same kind of control as used on power plant turbines. These turbochargers have minimal amount of lag, have a low boost threshold, and are very efficient at higher engine speeds. In many setups these turbos don't even need a wastegate. The vanes are controlled by a membrane identical to the one on a wastegate but the level of control required is a bit different. The first car manufacturer to use these turbos was the limited-production 1989 Shelby CSX-VNT. It utilised a turbo from Garrett, called the VNT-25 because it uses the same compressor and shaft as the more common Garrett T-25. This type of turbine is called Variable Nozzle Turbine (VNT). Turbocharger manufacturer Aerocharger use the term 'Variable Area Turbine Nozzle' (VATN) to describe this type of turbine nozzle.
    1st Pic: Standard Turbo, fixed exhaust turbine in solid housing.
    2nd Pic: VTG Turbo, variable exhaust turbine in solid housing.
    3rd Pic: VATN Turbo, fixed exhaust turbine in variable housing.
    4th pic: VATN Turbo animation
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    [QUOTE=Niko_Fx]Anybody can confirm this? Any release-dates for media-site pics?

    November next year! "maybe"?
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    that car looks cool. wouldnt mind driving that.
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    Fantastic car and like the VTG. Doesn't a twin-turbo setup do away with turbo lag? If Porsche is going the way of VTG will they keep twin-turbo or return to a single turbo arrangement?

    Like the looks but not crazy about the front grill? Is that a disguise or is that supposed to look aggressive?
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    Quote Originally Posted by PerfAdv
    Doesn't a twin-turbo setup do away with turbo lag?

    If Porsche is going the way of VTG will they keep twin-turbo or return to a single turbo arrangement?
    No, the twin turbo setup doesn't do away with lag. It reduces lag compared to a much larger single turbo that would produce the same power.

    Porsche will continue to use the twin-turbo setup with VTG because the lag reducing effect of the VTG will be a rather small improvement and the boxer 6-cylinder engines are much harder to turbocharge with a single turbo since the cylinder heads are on complete opposite sides of the engine block. Also the 997 series is an evolution of the 996, there is little blank slate redesigning going on. Equipping the 997 with a single turbo would mean a complete engine redesign which is extremely unlikely.

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    Quote Originally Posted by PerfAdv
    Like the looks but not crazy about the front grill? Is that a disguise or is that supposed to look aggressive?
    hah! That looks like a squirrel catcher grill to me. It looks like there's nothing behind those bars and they're there to keep debris and animals out of the radiator..

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    Quote Originally Posted by taz_rocks_miami
    It would be cool if the implemented Variable Turbine Geometry (VTG) to the new 997 Turbo. But I've read that the 996 Turbo doesn't suffer from turbo lag and thus no click-click-(boom!) as stated in the article.
    having a bi-turbo engine (i.e. one small and one larger turbo, small to sppol up quickly and provide torque, larger to provide more high end torque) such as the 996 turbo had, very effectively reduces turbo lag, thus the new system could only further reduce, although no, i dont believe there is any "click=click-boom" on any of the turbo 911's (barring 934 of course)
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    Quote Originally Posted by PBB
    No, the twin turbo setup doesn't do away with lag. It reduces lag compared to a much larger single turbo that would produce the same power.
    The way I understood twin-turbo setups doing away with lag was that a smaller turbo starts to spool up at low RPMs providing some boost but mainly exists so that when the larger turbo, which provides the real power, it doesn't come on after lag. Also, doing away with the on/off power delivery of a single large turbo. TT might not do away with lag but it does reduce it.

    I see what your saying though. VTG will improve power delivery regardless of setup.

    Porsche will continue to use the twin-turbo setup with VTG because the lag reducing effect of the VTG will be a rather small improvement and the boxer 6-cylinder engines are much harder to turbocharge with a single turbo since the cylinder heads are on complete opposite sides of the engine block. Also the 997 series is an evolution of the 996, there is little blank slate redesigning going on. Equipping the 997 with a single turbo would mean a complete engine redesign which is extremely unlikely.
    The boxer engine does present a challenge in this respect. Do you know whether the two turbos in Porsches are the same size?
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