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  1. #1
    Vern's Avatar
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    Max airflow SC mod

    I am curious why nobody has done this (or maybe someone has) ... one of the potential bottlenecks to our SCs seems to be the size of the opening in the front cover, especially with the larger high boost wheels. There is a good lip on the housing that is approximately 77mm OD, and the outer OD on the neck is only 72mm.

    If you cut off the stock neck you could bore the housing opening from 64/66/68 (stock/X SC/ET) to a full 72+mm, then just weld on a piece of aluminum tube that is 72mm ID and 77mm OD. Do some clean up of the weld inside the housing and you would have potentially more airflow.

    You could even possibly do better and get a 4" to 3" aluminum velocity stack that terminates with the 77mm od/72mm id and weld that on.

    Boring the housing to 68mm leaves it pretty thin and it just seems that it would allow more air & boost if we made the opening 72 or 73mm by doing the above.


  2. #2

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    I don't think there are any gains there. The inlet of a compressor is called the inducer. A compressor reaches "choke flow" when the air velocity reaches sonic velocity (yes, the speed of sound). At that point, you can't flow any more regardless of the size and speed of the wheel. For comparison, a turbocharger that can support 525 hp before choking only has a 57 mm inducer. So... numbers in the 60+ mm range can efficiently support 500++ hp while keeping the air velocity sufficiently low with minimal losses.

    However... any reduction in restriction will cause an increase in flow. So, by that theory, increasing the size of this will theoretically net more power, but I bet the gain isn't measurable.

  3. #3
    jpeconsult's Avatar
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    I couldn't even BS a reply like that. The man knows his stuff!

  4. #4
    ADAMBOMB's Avatar
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    Quote Originally Posted by jpeconsult View Post
    I couldn't even BS a reply like that. The man knows his stuff!

    hahaha +1

  5. #5
    ou812's Avatar
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    Quote Originally Posted by engineermike View Post
    I don't think there are any gains there. The inlet of a compressor is called the inducer. A compressor reaches "choke flow" when the air velocity reaches sonic velocity (yes, the speed of sound). At that point, you can't flow any more regardless of the size and speed of the wheel. For comparison, a turbocharger that can support 525 hp before choking only has a 57 mm inducer. So... numbers in the 60+ mm range can efficiently support 500++ hp while keeping the air velocity sufficiently low with minimal losses.

    However... any reduction in restriction will cause an increase in flow. So, by that theory, increasing the size of this will theoretically net more power, but I bet the gain isn't measurable.
    Umm, But will it work?

  6. #6
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by ou812 View Post
    Umm, But will it work?
    Looks cool but no. I tried this 2 years or so ago and measured zero gains. Not even 20 RPM.
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  7. #7
    Vern's Avatar
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    Delete per Jerry's post above ... at least we know since it has been tried already.
    Last edited by Vern; 01-20-2009 at 12:04 AM. Reason: Already tried

  8. #8
    ou812's Avatar
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    Quote Originally Posted by Green Hulk View Post
    Looks cool but no. I tried this 2 years or so ago and measured zero gains. Not even 20 RPM.
    Thanks...I was kidding though....

  9. #9
    Site Admin Green Hulk's Avatar
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    You would think it would work but i guess it doesn't for all the reasons engineermike laid out.

  10. #10
    speedskixp's Avatar
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    Quote Originally Posted by Green Hulk View Post
    You would think it would work but i guess it doesn't for all the reasons engineermike laid out.
    Also, I think the inducer blades on the wheel need to match the size of the inducer to perform correctly.

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