71/37 8mm Drive

Discussion in 'PSI Superchargers Tech Questions' started by TOL, Mar 6, 2021.

  1. TOL

    TOL Active Member

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    Looking to hear back from PSI screw users who might be running a 71/37 8mm drive deal.

    71/37 is pretty common for a 1.92:1 drive ratio, so I'm hoping there's a bunch of you guys out there?

    What's your belt life like?.......
     
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  2. TOL

    TOL Active Member

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    Nobody out there?........
     
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  3. Mike Canter

    Mike Canter Top Dragster
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    Are you using a Two Step? If so then 3 runs
     
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  4. rb0804

    rb0804 Active Member

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    Is that starting to eat teeth after 3 runs and it’s gonna chuck it on the fourth?
     
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  5. TOL

    TOL Active Member

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    Thanks Mike.

    Okay, so a lot of roots guys 2-step an 8mm belt and I don't hear them complaining about belt life. So what's the difference, the fact that they have a 5 inch or so top pulley diameter?
     
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  6. Mike Canter

    Mike Canter Top Dragster
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    The upper pulley is smaller so belt makes a sharper bend but the big thing is there is lots more friction and mass in the roots blower that in the screw blower. The lack of friction and mass makes the blower jump around and thus the belt jump back and forth in the grooves of the pulley when on the Two Step and rips cords in the belt.
     
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  7. TOL

    TOL Active Member

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    Is the situation any better or worse with or without the quill shaft in place?
     
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  8. kosky racing

    kosky racing Comp Eliminator

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    ???
     
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  9. Mike Canter

    Mike Canter Top Dragster
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    You cannot run a screw blower without the quill shaft. It connects the front gears drive to the pulley flange.
     
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  10. TOL

    TOL Active Member

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    What I meant was the RCD screw drive, which is effectively a solid direct drive without any "quill" action versus using the PSI drive with a quill shaft.
     
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  11. Mike Canter

    Mike Canter Top Dragster
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    I believe that fixes the broken Quill shaft problem and not the belt breakage problem
     
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