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    Overboost question

    I was reading on another forum and this guy claims that the overboost does not work in 5th or 6th or above 5K rpms. Is this true? If it is, when would the overboost even be on during a full boil take off thru the gears. I mean you almost always stay above 5K when really getting on it. Thoughts?

    Re: Overboost question

    Quote:
    355Spider said:
    I was reading on another forum and this guy claims that the overboost does not work in 5th or 6th or above 5K rpms. Is this true? If it is, when would the overboost even be on during a full boil take off thru the gears. I mean you almost always stay above 5K when really getting on it. Thoughts?




    Overboost is available between 2100-4000 rpms. It is only realized under full throttle applications. It progressively diminishes at 4000 and ceases to be available at or about 5000 rpms. Any shifts above that point do not allow for the availability of the overboost option.
    In the event of a full throttle run through the gears, overboost would only be available in first gear, if the car was launched below the aforementioned revs.

    Re: Overboost question

    SO basically if you are doing an acceleration run at full boil it's almost useless except in the beginning of 1st gear. After you get the engine in it's sweet spot it vanishes. Seems a little pointless.

    Re: Overboost question

    Quote:
    355Spider said:
    SO basically if you are doing an acceleration run at full boil it's almost useless except in the beginning of 1st gear. After you get the engine in it's sweet spot it vanishes. Seems a little pointless.



    It's not there to alter maximum performance. It's there to make the car more drivable in less than 100% situations, such as a spirited drive on a winding road, or commuting on a freeway.

    Re: Overboost question

    Quote:
    355Spider said:
    SO basically if you are doing an acceleration run at full boil it's almost useless except in the beginning of 1st gear. After you get the engine in it's sweet spot it vanishes. Seems a little pointless.





    ?

    Re: Overboost question

    Quote:
    devo said:
    Quote:
    355Spider said:
    I was reading on another forum and this guy claims that the overboost does not work in 5th or 6th or above 5K rpms. Is this true? If it is, when would the overboost even be on during a full boil take off thru the gears. I mean you almost always stay above 5K when really getting on it. Thoughts?




    Overboost is available between 2100-4000 rpms. It is only realized under full throttle applications. It progressively diminishes at 4000 and ceases to be available at or about 5000 rpms. Any shifts above that point do not allow for the availability of the overboost option.
    In the event of a full throttle run through the gears, overboost would only be available in first gear, if the car was launched below the aforementioned revs.


    Devo thanks for the post. Your one gear theory, probably has implications to future tuning programs..if they simply modify the over boost characteristics,voila faster exceleration...without too much stress on the engine...if what you are saying is true and it makes some sense that it is, remapping should eventually make this a wickedly fast car(not that it's slow now). The only way this wouldn't hold, would be if the boost and or rev range available to boost was going to generate to much pressure on the engine. Someone wrote on a previous thread, an engineer with Porsche claimed the engine could easily handle 1.4 bar of boost. Unfortunately I can't recall who posted that information
    If it were possible to have the boost rev range elevated as one climbs the gears, then it would be easy to see how much more could be squeezed from the engine once one gets past first gear. I find it difficult to shift at high revs ( when I am trying to tear up the road and not hit the rev limiter (especially in first and second..therefore if the engine can handle extended boost up to it's rev limiter, this car would be faster cause the turbo boost would be available longer and utilized as such with more tourqe. Wouldn't this make sense or is the law of diminishing returns at work to the point where the touque can't easily be extracted?

    Re: Overboost question

    You're right, that would make for a wickedly fast(er) car. Congrats on your turbo. Mine is the same color combo, w/ stick, of course

    Re: Overboost question

    And that's exactly what the tuners have in store for this car. Better make sure you get the Sport Chrono option.

    Re: Overboost question

    I see. It basically just gives that car more mid range punch but not neccessarily that much more maximum performance. Makes sense for the daily feel of the car.

    Re: Overboost question

    This is correct and is why it does not increase the maximum horsepower. It does increase the effective mid range torgue and horsepower. There is a good chart in the 997TT brochure that depicts this.

    Re: Overboost question

    Quite impressive when compared against the GT2 and X50.

    Re: Overboost question

    Hi there, the following might answer your questions:
    On my car, end of first gear is around 40 mph. when you change to second gear, 40 mph equals 4500 rpm which means your are beyond the peak torque of 505 but still higher than 460.
    Top of second gear is around 70 mph, when you change to third, 70 mph equals again about 4500 rpm, so you are still getting more than 460 but less than 505 of torque.
    top of third gear is around 100 mph, changing to 4th at 100mph equals 5000 rpm so you are getting only 460 of torque from that point on.
    Summary: from first to end of 3rd gear (100 mph), you are definitely using the overboost benefit although not the complete 505 available only in first.
    Hope that explained a little.

    Re: Overboost question

    Quote:
    aah986 said:
    Hi there, the following might answer your questions:
    On my car, end of first gear is around 40 mph. when you change to second gear, 40 mph equals 4500 rpm which means your are beyond the peak torque of 505 but still higher than 460.
    Top of second gear is around 70 mph, when you change to third, 70 mph equals again about 4500 rpm, so you are still getting more than 460 but less than 505 of torque.
    top of third gear is around 100 mph, changing to 4th at 100mph equals 5000 rpm so you are getting only 460 of torque from that point on.
    Summary: from first to end of 3rd gear (100 mph), you are definitely using the overboost benefit although not the complete 505 available only in first.
    Hope that explained a little.



    I guess that depends on how fast you shift.

    Re: Overboost question

    Quote:
    aah986 said:
    Hi there, the following might answer your questions:
    On my car, end of first gear is around 40 mph. when you change to second gear, 40 mph equals 4500 rpm which means your are beyond the peak torque of 505 but still higher than 460.
    Top of second gear is around 70 mph, when you change to third, 70 mph equals again about 4500 rpm, so you are still getting more than 460 but less than 505 of torque.
    top of third gear is around 100 mph, changing to 4th at 100mph equals 5000 rpm so you are getting only 460 of torque from that point on.
    Summary: from first to end of 3rd gear (100 mph), you are definitely using the overboost benefit although not the complete 505 available only in first.
    Hope that explained a little.



    But if you drive slowly in 5th gear in then range of 2500 rpm and you would like to overtake a car, you press full throttle and voilá overboost for maximum 10 seconds or you reach 5000 rpm. So it works also in 5th gear.

    AM

     
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