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  1. #1
    Greenhulk Grasshopah (DRC) HallPass's Avatar
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    just wondering why SC impellers are bigger..

    Obviously the higher boost SC's impellers have a bigger impeller diameter, and the blades on the impeller are taller/different pitch.

    Compared to doing this, why don't that make higher boost SC's that have taller blades in them.

    What I mean is say the stock blade on the impeller wheel is 1" tall. Why don't the High performance ones be like 4" tall with a lighter pitch?

    Your pushing more air. It would be the same diameter wheel. The Supercharger would have a HUGE spacer on it, and would be very very thick.

    I am just wondering what the reason is they do not do this.

    To me the higher boost superchargers the point is bigger wheel different pitch of blades on the impeller pushes the air out more and higher boost. Making the blades taller would have a larger surface area to push the blades out..

    just curious hope this all makes sense.


  2. #2
    formerly Gold06RXP Turbo Nick's Avatar
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    May have something to do w/ balance? Maybe the spacer is only efficient to a certain point then it starts working against you?
    Quote Originally Posted by HallPass View Post
    Obviously the higher boost SC's impellers have a bigger impeller diameter, and the blades on the impeller are taller/different pitch.

    Compared to doing this, why don't that make higher boost SC's that have taller blades in them.

    What I mean is say the stock blade on the impeller wheel is 1" tall. Why don't the High performance ones be like 4" tall with a lighter pitch?

    Your pushing more air. It would be the same diameter wheel. The Supercharger would have a HUGE spacer on it, and would be very very thick.

    I am just wondering what the reason is they do not do this.

    To me the higher boost superchargers the point is bigger wheel different pitch of blades on the impeller pushes the air out more and higher boost. Making the blades taller would have a larger surface area to push the blades out..

    just curious hope this all makes sense.

  3. #3
    R88ory RXP's Avatar
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    Also wieght is a massive issue with the design of our charger. The clutch would not hold up with a massive heavy wheel on the end.

    I think that the spacers will get thicker and thicker as the big boys manage to improve the relibilty of the clutch and washers.

    We already have a charger that can make 20psi you cant go much further without changing alot of other stuff. The manifold will not take much more than that 22psi is the consisdered max on stock intake manifold then the internall of the engine will need to be looked at. R88

  4. #4

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    Hallpass, you're hitting on a VERY complex issue around impeller design. Without getting into the details (some folks spend their entire careers doing designing impellers), you're talking about making the impeller "more axial" rather than "radial flow". In impeller terms, this has a higher "specific speed", meaning it would be optimized for higher flows and lower pressures. This could actually move the peak efficiency to a flow higher than the 4-tec can handle, and you lose efficiency at the operating point.

  5. #5
    Greenhulk Grasshopah (DRC) HallPass's Avatar
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    Quote Originally Posted by engineermike View Post
    Hallpass, you're hitting on a VERY complex issue around impeller design. Without getting into the details (some folks spend their entire careers doing designing impellers), you're talking about making the impeller "more axial" rather than "radial flow". In impeller terms, this has a higher "specific speed", meaning it would be optimized for higher flows and lower pressures. This could actually move the peak efficiency to a flow higher than the 4-tec can handle, and you lose efficiency at the operating point.

    and you couldn't reconstruct parts of the engine to make it handle this boost?

  6. #6

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    Quote Originally Posted by HallPass View Post
    and you couldn't reconstruct parts of the engine to make it handle this boost?
    Well...the engine would simply have to move more air to get the higher specific-speed compressor to its peak efficiency. You could bore/stroke/port/cam, etc..., which would all move things in the right direction.

    ...but I like the way you're thinkin'!

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