Power difference between Roots and Screw??

Discussion in 'PSI Superchargers Tech Questions' started by Lonnie Houde, Jun 8, 2006.

  1. Lonnie Houde

    Lonnie Houde Member

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    Can any of you guys give an honest guess/fact on the power difference between a good Roots blower ie, "Modified Kobelco K-11 or PSI Roots" and a new "C" rotor screw. "I know the screw can make a lot more boost, at a cooler charge, but, assuming the boost levels are the same, what is the power difference on say a 500" motor that breathes well??

    Thanks, Lonnie
     
    #1
    Lonnie Houde, Jun 8, 2006
  2. Mike Canter

    Mike Canter Top Dragster
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    Well it only takes about 150hp to turn a screw blower whereas anywhere from 350 to 550 hp to turn a roots blower depending on how tight it is. You have to figure that the best a good roots blower motor is going to get you is probably around 2500-2600 hp and a screw blower motor will be 2700-2800 HP. There are racers that have made more in each but that should be a good average.
     
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    Mike Canter, Jun 9, 2006
  3. eli

    eli Banned

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    the key to your question, a cooler charge! @ lets say 45 lb.for both, a roots is putting out 45 lb. of hot expanded air where the screw is much cooler, and will make ( from what iv heard ) 500 more h/p its like the bunny, it keeps going and going.:cool:
     
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    eli, Jun 9, 2006
  4. shawn davis

    shawn davis Member

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    Screw Comparison

    Not A Similar Engine, But We Dynoed A 572 Chevy Pump Gas Carbs 12 Lbs Of Boost Offshore Boat Engine.14-71 Made 948, Old Style Whipple At The Same Boost Made 1160. 212 More Hp With No Other Changes. I Can Imagine Probably Double That With More Overdrive And Boost On Alcohol, I'd Say 400 Minimum Is Real Close
     
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    shawn davis, Jun 9, 2006
  5. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    C

    there's probably several hundred hp going from a d psi to a c psi....

    so going from a roots to a c blower, the mother of all blowers, i would say a minimum of 600-700 hp.....with the blower turned up.

    you can make a lot of boost at a lower od and not have to rev it as hard. the c blower makes enough boost that it should make all the boost your heads can handle airflow wise.
     
    #5
    Will Hanna, Jun 9, 2006
  6. Nathan Sitko - 625 TAD/TAFC

    Nathan Sitko - 625 TAD/TAFC TAD / TAFC

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    We made 52psi boost in our TAFC with a brand new littlefield with kobelco k-11 rotors last weekend at Mission.
     
    #6
    Nathan Sitko - 625 TAD/TAFC, Jun 9, 2006
  7. M Tigges

    M Tigges TAFC

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    Also roots rotors have to work very hard against the pressure in the manifold which kills power! if your wood screws were like high helix rotors you would never get them started...LOL
     
    #7
    M Tigges, Jun 9, 2006
  8. Lonnie Houde

    Lonnie Houde Member

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    I really appreciate your input guys.

    Thanks, Lonnie
     
    #8
    Lonnie Houde, Jun 9, 2006

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