8-71 vs 14-71 boost

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by NITROBANDIT1, Aug 1, 2011.

  1. NITROBANDIT1

    NITROBANDIT1 LOST IN SPACE

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    i have a interesting problem im trying to solve. we run a 14-71 hi helix ml with just the teflon strips in it in a kb 511. we are limited to 30% od at normal altitudes, and 43% at high altitudes. i also have a 8-71 ml std rotor with both sets of strips and we are allowed any od on. do you think the 8-71 could make as good or better boost with the unlimited od, or will it not pass enough volume to do it? havent tried it yet, wondering how it might work. any thoughts? im sure the 8-71 would take less hp to run, but not sure about the boost numbers. thanks, dan
     
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  2. andy wilfong

    andy wilfong Member

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    It's interesting that you say the 14-71HH only has Teflon strips, in the 32 yrs I've been there I have never built one that way, a good rule of thumb for different blower sizes if all is the same is about 6% per size, for example, an 8-71 would be 18% less than the 14-71, the high helix will always make more power in the 35-40 % overdrive range
     
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  3. Eric

    Eric Member

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    It is a mooneyham...
     
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  4. andy wilfong

    andy wilfong Member

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    Either way the high helix will still be better, remember boost isn't horsepower if it makes to much heat to get it and the parasitic loss of turning a small blower faster is greater,
     
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  5. NITROBANDIT1

    NITROBANDIT1 LOST IN SPACE

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    Super sucker

    well, since thats not going to work out, what does a new lb20 hi helix do compared to say the mooneyham unit? is it better than a kobelco superman for a 30% deal?
     
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  6. andy wilfong

    andy wilfong Member

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    So far every application that is running an LB-20 has had success and is very pleased, from nostalgia fuel, tractor pullers and AA- gas cars, we have done a lot of work to get the boost up, manifold temp down, and parasitic loss of turning the supercharger lower, so far all of those goals have been met, our of the shelf blower doesn't need any "upgrades" we do everything that we can to our production models
     
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  7. 55 bel air

    55 bel air New Member

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    8/71

    We run a 8/71 mooney ham retro blouwer on a 500ci chevy with a small intake air size,we have 29% od and it makes 25-28 lb off boost how much will it make @ 40% od ;).

    thanks
     
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