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Thread: Twin Turbos

  1. #31
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    Quote Originally Posted by henk4 View Post
    My car has an OEM system.....so that answers the question.
    ...and only at that power level.

  2. #32
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    Quote Originally Posted by CapnBoost View Post
    ...and only at that power level.
    no need to become cryptic here.
    "I find the whole business of religion profoundly interesting, but it does mystify me that otherwise intelligent people take it seriously." Douglas Adams

  3. #33
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    Quote Originally Posted by henk4 View Post
    no need to become cryptic here.
    I own a 3rd gen rx-7 with sequential turbos. Eventually the system either breaks down, or becomes a restriction on the quest for more power. On our cars, it's wholly possible to move to a single turbo and get more torque at the same low rpm (you feel more lag, but at the same time the car is making more torque) as the stock sequentials.

    All in all, we're trying to quantify "better" as it relates to turbo configuration. I don't think that this is possible, there's no free lunch and there's no universal "good" that we can compare against.

    So if minimal lag and the illusion of more accelerative force is the ideal then yes, sequential twins are "the best."

    But, more power will usually be delivered by a single larger turbo.

  4. #34
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    Quote Originally Posted by CapnBoost View Post
    So if minimal lag and the illusion of more accelerative force is the ideal then yes, sequential twins are "the best."

    But, more power will usually be delivered by a single larger turbo.
    nobody said "the best", we were talking about better, in relative terms. I see that you have been experimenting with non-oem stuff, which might not be the right basis for an overall judgement. You mentioned it yourself, if twin turbo is OEM it might be better.
    And there is no illusion of more accelerative force, it is reality. I had the about the same power in my previous car, in which I had the engine management changed a little and yet it did not provide the same acceleration as my current car (before I had that upgraded...)
    "I find the whole business of religion profoundly interesting, but it does mystify me that otherwise intelligent people take it seriously." Douglas Adams

  5. #35
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    No, it's the illusion of more acceleration. A big single that is not yet fully spooled but still making more torque will accelerate faster than sequential turbos even though it feels laggy. Corky Bell states this clearly in Maximum Boost- "The idea that a superpowerful, maximum-effort turbo car would be fun to drive at full throttle but be a bit of a cantankerous beast at low speeds is not unreasonable on the surface. This idea does not, however, hold up under closer scrutiny."

    This site allows you to compare dyno plots between Rx-7s with certain mods. The red line is a car with a t04 single turbo, the green line is a car with upgraded aftermarket twins (sequentially), the blue line is a car using stock sequential twin turbos. The single is making more torque than the sequential cars from 3500-4500rpm, at 3-4psi less than the twin systems.

  6. #36
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    I think it is a bit far fetched to compare the figures from a rotary engine, with those coming from a diesel, don't you think?
    I stick to my claim that my single turbo/remapped diesel with similar power to the standard mapped twin turbo version of the same engine had less acceleration.
    "I find the whole business of religion profoundly interesting, but it does mystify me that otherwise intelligent people take it seriously." Douglas Adams

  7. #37
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    Quote Originally Posted by henk4 View Post
    I think it is a bit far fetched to compare the figures from a rotary engine, with those coming from a diesel, don't you think?
    I stick to my claim that my single turbo/remapped diesel with similar power to the standard mapped twin turbo version of the same engine had less acceleration.
    I'm not comparing a rotary to a diesel- I'm comparing 3 rotaries. Unless you have some dyno plots of that diesel with single and twin turbos, stock and aftermarket, etc, etc.

    I'm trying to show how terribly subjective this is.

  8. #38
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    Quote Originally Posted by Wouter Melissen View Post
    No in this case the twin-turbo setup is relatively and actually better; there is less lag. You were wrong and posting very long rants does not that change or hide that.

    I disagree. I maintain that it is relatively better and not actually better.

  9. #39
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    Quote Originally Posted by henk4 View Post
    The Veyron engine is probably a very poor piece of engineering in your book
    I can answer this. This is easy! First of all, the larger the engine, the higher the probability that it will require a bi-turbo instead of a single turbo if you want to make some significant amount of power. Moving large air volumes with large vortices and turbulence up to the combustion chamber of that many cylinders, is no small task. I beleive the veyron is a v12 ( I am not sure).

    Simply on the basis of engine size, a bi-turbo would certainly make sense for Veyron. I bet the bi-turbos of the Veyron are very large ones at that. I wouldn't be surprised if two sequential bi-turbos or a quad turbo, are used for the Veyron in the future.
    Last edited by G35COUPE; 09-28-2009 at 11:08 AM.

  10. #40
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    Quote Originally Posted by CapnBoost View Post
    I'm not comparing a rotary to a diesel- I'm comparing 3 rotaries. Unless you have some dyno plots of that diesel with single and twin turbos, stock and aftermarket, etc, etc.

    I'm trying to show how terribly subjective this is.
    my dyno is in my ass (No I don't have the graphs, would the official figures, toque, BHP and those supplied by the tuners, do?).
    "I find the whole business of religion profoundly interesting, but it does mystify me that otherwise intelligent people take it seriously." Douglas Adams

  11. #41
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    Quote Originally Posted by G35COUPE View Post
    I can answer this. This is easy! First of all, the larger the engine, the higher the probability that it will require a bi-turbo instead of a single turbo. Moving large air volumes with large vortices and turbulence up to the combustion chamber of that many cylinders, is no small task. I beleive the veyron is a v12 ( I am not sure).

    Simply on the basis of engine size, a bi-turbo would certainly make sense for Veyron. I bet the bi-turbos of the Veyron are very large ones at that. I wouldn't be surprised if two sequential bi-turbos or a quad turbo, are used for the Veyron inthe future.
    I think the Veyron engine was already further developed than you seem to have noted.....

    2008 Bugatti Veyron 16.4 Fbg par Hermes - Images, Specifications and Information
    "I find the whole business of religion profoundly interesting, but it does mystify me that otherwise intelligent people take it seriously." Douglas Adams

  12. #42
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    an interesting comparison would be between the two versions of the Porsche 962, the one with the twin turbo lay-out and the one that raced in the USA under IMSA regulations with a single turbo.
    "I find the whole business of religion profoundly interesting, but it does mystify me that otherwise intelligent people take it seriously." Douglas Adams

  13. #43
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    Quote Originally Posted by henk4 View Post
    I think the Veyron engine was already further developed than you seem to have noted.....

    2008 Bugatti Veyron 16.4 Fbg par Hermes - Images, Specifications and Information
    Thanks for the info. I had no idea that info was there. I was mostly speaking from theory on air flow. The idea is to move the air from laminar to turbulent flow, and keep it that way and as cool as possible, until the air is ready to be mixed with the fuel in the coombustion chamber. Without a doubt, auto manufacturers who produce cars with bi-turbos may hve done their homework after spending tons of money, and thus produced a bi-turbo that meets the theory that i have just laid out. Of course, for them to do so, they would have designed an intake plenum that would allow the air to create enough vortices before it enters the combustion chamber. Its hard to achieve the same with after-market parts without spending tons of money to do so.

    By the way, the 350z and G-35 coupe which are basically the same cars under the hood, use two slightly different piping systems for thier intake systems. The 350 z piping is more efficient and produces slightly more power, than the G-35 coupe air piping. So, i removed every bit of the baffles and the air intake system of my G-35 Coupe and replaced it with a 350Z after market intake piping system. Its a little louder but it makes the power i need these days.
    Last edited by G35COUPE; 09-28-2009 at 11:09 AM.

  14. #44
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    Quote Originally Posted by henk4 View Post
    my dyno is in my ass (No I don't have the graphs, would the official figures, toque, BHP and those supplied by the tuners, do?).
    An aerospace engineer once told me- "One scientific test is better than a thousand expert opinions."

    Quote Originally Posted by henk4 View Post
    an interesting comparison would be between the two versions of the Porsche 962, the one with the twin turbo lay-out and the one that raced in the USA under IMSA regulations with a single turbo.
    Indeed.

    On the Veyron, it's my humble opinion that the engine is the least impressive engineering feat present in that car. Chassis, aero, and the driveline are far more impressive than a 16cyl quad turbo engine making 987 SAE horsepower.

  15. #45
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    Quote Originally Posted by G35COUPE View Post
    Thanks for the info. I had no idea that info was there.
    Info is the very raison d'etre of this site. (not this forum) Feel free to consult the vast amount of data.
    "I find the whole business of religion profoundly interesting, but it does mystify me that otherwise intelligent people take it seriously." Douglas Adams

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