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The Little Fins Under The Car

Discussion in 'Gen 3 Prius Main Forum' started by El Dobro, May 18, 2013.

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  1. F8L

    F8L Protecting Habitat & AG Lands

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    That is the older brace design. It's not my picture or car. :)

    During on of the technical sessions at To Go Before, one of the Toyota Accessories specialists talked about the Performance Plus Package and how they used addititional fins on the ground effects package to smooth out airflow at the rear of the car. In stock form there is a small pocket of turbulent air directly behind the car. The rear ground effects help smooth out the flow. He had some interesting graphic displays. I'll see if I can find them.
     
    #21 F8L, Jun 18, 2013
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  2. El Dobro

    El Dobro A Member

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    Fins or air-benders?
     
    #22 El Dobro, Jun 18, 2013
  3. F8L

    F8L Protecting Habitat & AG Lands

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    More of a set of fins than air benders.
     
    #23 F8L, Jun 18, 2013
  4. F8L

    F8L Protecting Habitat & AG Lands

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    The bottom of the rear skirt of the Performance Plus package.

    20130619_074722.jpg
     
    #24 F8L, Jun 19, 2013
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  5. David Beale

    David Beale Senior Member

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    You're talking about those little nobs on the bottom of the bumper-cover extension? Sorry, those would do nothing!
    Here's a question. Does the "performance package" get better rated mileage than the standard Prius? If not it's mental performance not real performance.
     
    #25 David Beale, Jun 19, 2013
  6. F8L

    F8L Protecting Habitat & AG Lands

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    David, I'm going off of reports from Toyota. They ran the design through CFD simulation by SimTech ANSYS. This was repeated by one of the Toyota Accessory specialists during last weekend's technical sessions which included the simulation videos.
     
    #26 F8L, Jun 19, 2013
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  7. WE0H

    WE0H Senior Member

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    I am pretty sure I read that the Plus Perf body kit was designed to reduce wind drag over stock :)

    Mike

    Mobile on my SGH-i717
     
    #27 WE0H, Jun 19, 2013
  8. F8L

    F8L Protecting Habitat & AG Lands

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    We know the Performance Plus package will reduce FE vs. a standard Prius Two, Three or Four. The Prius Five also suffers reduced FE but Toyota didn't submit a change in EPA rating for it. So what you are asking for is not relevant to reality.

    Aerodynamics could be enhanced but the resulting FE is still lower than a standard Prius because of the wheels, tires, sway bar etc.. I think the engineers were simply trying to reduce the FE hit in any way they could without costing an arm and a leg. This is how it was explained to us.
     
    #28 F8L, Jun 19, 2013
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  9. El Dobro

    El Dobro A Member

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    They should use more air-benders. :p
     
    #29 El Dobro, Jun 19, 2013
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  10. szgabor

    szgabor Active Member

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    I got under the car with my camera .... this is a 2012 Prius II so it may different from others but I can see two air bender little stuff I am really sceptical what this can do .. .BUT would Toyota put them there for nothing ???

    not sure any comments

    oh yes the pictures are up side down ... that is the way I could put the camera and the flash under ..

    IMG_2158.JPG
    IMG_2159.JPG
    IMG_2160.JPG
     
    #30 szgabor, Jun 23, 2013
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  11. szgabor

    szgabor Active Member

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    No question those are not just random pieces .....
     
    #31 szgabor, Jun 23, 2013
  12. El Dobro

    El Dobro A Member

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    The attached articles from Lexus show how small they are and according to them, they work.
     
    #32 El Dobro, Jun 23, 2013
  13. szgabor

    szgabor Active Member

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    well "they work" OK what exactly that means and how ??

    I am sure Toyota will not waste that pieces for nothing.
     
    #33 szgabor, Jun 23, 2013
  14. El Dobro

    El Dobro A Member

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    Link on post#9 Little Miracles.
     
    #34 El Dobro, Jun 23, 2013
  15. szgabor

    szgabor Active Member

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    That says NOTHING how and why this should work COOL sure but WHAT those thingies DO ???

    sorry
     
    #35 szgabor, Jun 23, 2013
  16. szgabor

    szgabor Active Member

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    I read that it doesn't say how and why it works one sentence "These fins streamline the airflow under the car, boosting grip and reducing wind noise" ... sure generally it has something to do with airflow but gives NO explanation or test numbers "boosting" grip from what to what at what speed ???

    Sure we can believe lexus magic and also sure they wouldn't put even that much plastic there for nothing.
     
    #36 szgabor, Jun 25, 2013
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  17. El Dobro

    El Dobro A Member

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    I guess they just didn't want to get too technical since it's only a magazine article and it's geared towards Lexus owners. The articles also say that the air-bender design is also incorporated into the mirrors, but doesn't say exactly how.
     
    #37 El Dobro, Jun 25, 2013
  18. Tideland Prius

    Tideland Prius Moderator of the North
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    They're there to make the air flow exiting under the vehicle more laminar.
     
    #38 Tideland Prius, Jun 26, 2013
  19. WE0H

    WE0H Senior Member

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    Does that mean smoother airflow? :)

    Mike

    Mobile on my SGH-i717
     
    #39 WE0H, Jun 26, 2013
  20. David Beale

    David Beale Senior Member

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    Laminar flow means minimal turbulence, which most would consider "smoother".
    But I still think those tiny fins would have very little effect at any air speed you could drive a Prius at. Just look at how big rear "spoilers" have to be to have an effect at legal speeds!
    But the Prius is at the 99th percentile level re aero effects, so I guess the engineers would be happy with 1-2%.
     
    #40 David Beale, Jun 27, 2013
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