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    Twin Screw Vs. Roots - Kenne Bell Article

    Amazing article from Kenne Bell, contains pictures and very simple explanations of the difference between Twin Screw and Roots Blowers. Contains tests showing temperatures, cfm, and parasitic losses.

    http://www.kennebell.net/techinfo/ge...romcatalog.pdf

    Tried to figure out how to paste it here but couldnt.


    Also, I couldnt find the info on it, but I was trying to figure out if both are belt driven, how come the twin screw can develop max boost so low, why doesnt the boost keep building like in the centrifugal blower?
    Last edited by DD GT3 RD; 05-27-2011 at 11:21 PM.
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    MAO!
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    It's a good article but they obviously view the twin screw favorably because that is what they will which is fine.

    The question mark is you never really see positive displacement on high revving motors and some people say they don't like to rev.

    Either way, it's worth a read to learn.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    It's a good article but they obviously view the twin screw favorably because that is what they will which is fine.

    The question mark is you never really see positive displacement on high revving motors and some people say they don't like to rev.

    Either way, it's worth a read to learn.
    I've always heard they dont like to rev high as well, but the article explains the internal difference well.

    Any input on this - I couldnt find the info on it, but I was trying to figure out if both (twin screw and centrifugal) are belt driven, how come the twin screw can develop max boost so low, why doesnt the boost keep building like in the centrifugal blower? It would seem to be a linear thing if its belt driven.


    I was doing research on bleeding boost off on a centrifugal blower. For instance you run 8psi of boost on the m3, say 4psi is hit at 4200rpm, 8psi at 8400rpm. Now if you ran 16psi, 8psi would hit by 4200rpm but then couldnt there be a waste gate, or some pressure release gauge that would release the the extra psi after so it never surpased 8psi to redline, this way you would have more of the twin screw effect? I found the idea had been brought up but no real info on it.
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    Click here to enlarge Originally Posted by DD GT3 RD Click here to enlarge
    Any input on this - I couldnt find the info on it, but I was trying to figure out if both (twin screw and centrifugal) are belt driven, how come the twin screw can develop max boost so low, why doesnt the boost keep building like in the centrifugal blower? It would seem to be a linear thing if its belt driven.
    Well I might explain this wrong or not have the full grasp myself but the positive displacement is not increasing boost or generating more with engine rpm. Whatever it spins at while the engine is at low rpm it what it spins it while in high rpm likely due to some gear reduction I would think. I'd have to read more in depth but with a centri you are sort of spinning a turbo impeller so the more you spin it the more boost.

    Click here to enlarge Originally Posted by DD GT3 RD Click here to enlarge
    I was doing research on bleeding boost off on a centrifugal blower. For instance you run 8psi of boost on the m3, say 4psi is hit at 4200rpm, 8psi at 8400rpm. Now if you ran 16psi, 8psi would hit by 4200rpm but then couldnt there be a waste gate, or some pressure release gauge that would release the the extra psi after so it never surpased 8psi to redline, this way you would have more of the twin screw effect? I found the idea had been brought up but no real info on it.
    I see what you are saying but excess pressure is bled off in these SC's as is, that is why you have a BOV with the gintani SC. Bypass valve, blow off valve, either way excess pressure is bled off.

    I don't see how you would have a twin screw effect as there will always be the lag until the impeller is spinning whereas the positive displacement is generating its boost always hence why it is difficult to make it work with independent throttle bodies and blowing into them vs. pulling through them.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I don't see how you would have a twin screw effect as there will always be the lag until the impeller is spinning whereas the positive displacement is generating its boost always hence why it is difficult to make it work with independent throttle bodies and blowing into them vs. pulling through them.
    thanks for trying to answer the first part, I see u what you meant.

    but for the above, meant "twin screw like" because if this was possible max boost would come very early, not just at max rpm...it wouldnt be off idle like a twin screw but you could have it by a few thousand rpm.
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    Click here to enlarge Originally Posted by DD GT3 RD Click here to enlarge
    but for the above, meant "twin screw like" because if this was possible max boost would come very early, not just at max rpm...it wouldnt be off idle like a twin screw but your could have it by a few thousand rpm.
    That would be awesome just don't see how it would be possible.

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