Aero Modifications?

Discussion in 'Gen 2 Prius Fuel Economy' started by coonbutt, Apr 3, 2007.

  1. coonbutt

    coonbutt New Member

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    Has anyone done any improvements to the aerodynamics of their Prius? I realize that is very smooth as it is, but even subtle changes can make a huge difference over time. There are a lot of people at gassavers.org that alter their vehicles quite a bit to maximize efficiency. A couple of the normal ICE cars there get into the upper 60s to 70 mpg!

    One thing that seems to help is blocking over some parts of the grill. This not only warms the ICE faster, but improves aerodynamics, since the air that would have gone through and bounced all over the place is redirectly around the body. Has anyone blocked part of their grill year-round?

    Weight reduction is also a big thing there, as is turning your car off on down hills and at stoplights (like the Prius). One of the guys there borrowed a Prius for a week and averaged around 75 mpg!

    Belly pans are also common, which may help on the Prius too. It is smooth underneath there, but it could be smoother.
     
  2. efusco

    efusco Moderator Emeritus
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    a few folks have used pizza pans to cover the wheels to make them smooth, I think a couple people have enclosed the rear wheel wells temporarily. There's also a sport package for lower skirts available.

    Oh, I replaced my whip antenna with a shark fin...I'm sure that gave me an extra 10mpg!
     
  3. coonbutt

    coonbutt New Member

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    <div class='quotetop'>QUOTE(efusco @ Apr 3 2007, 08:52 AM) [snapback]416972[/snapback]</div>
    Any postive test results for these modifications? (Other than the shark fin, of course, which I bet is closer to 15 mpg extra :D )
     
  4. efusco

    efusco Moderator Emeritus
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    <div class='quotetop'>QUOTE(prickly commute @ Apr 3 2007, 08:02 AM) [snapback]416976[/snapback]</div>
    not sure.
     
  5. donee

    donee New Member

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    <div class='quotetop'>QUOTE(prickly commute @ Apr 3 2007, 10:39 AM) [snapback]416969[/snapback]</div>
    The Prius has a Cd (Coefficient of Drag) of .26, which is allot better than the typical car (about .3). Allot of the simple mods are already integrated into the Prius. It already has some belly pans.

    Yep, allot of people have blocked the grill partiallly, or completely in the cold weather. I have the top grill blocked and the bottom grill half blocked on my car, in the near freezing weather. The inverter heat exchanger is on the driver's size, and the transmision is cooled by airflow over it, and its also on the driver's side. The belly pan is absent of the driver's side as well, to let the air flow out under the car there.

    Full wheel covers do add weight, which has to be spun up and down, using fuel. The commercially avaliable covers are deeply dished. At constant speed, they could help. A rear wheel arch cover might help, but would require some pattern making, as the wheel wheels are close to flush there, and the cover would need to stick out further than the arch edges.

    One mod that might help is to extend the hood over the windshield wipers, and remove the rear wiper.

    Another mod would be to remove the external rear-view mirrors, and replace them with small cameras, and internal screens. Somewhat expensive, but it whould help the Cd.

    I think strakes along the edges of the hatch might help, but could easily be made oversized and make things worse. This would help spill over and reduce the cross section of disturbed air, possibly.

    Vortex generators on the upper 1/4 of the windscreen might be made to keep the air from shooting as high over the top of the car, and reduce the area of the air that is disturbed. On the trailing edge, like on the Mitsubishi, I do not thing they would work. On the Mitsubishi they are used to direct air down the steep rear window of that car and the Prius has a carefully designed shallow angle there.

    The Hybrid X concept had side dams up each side of the windsheild. Probably to reduce air density of the flow over the rear-view mirrors. Increased density there would cause more drag as it tumbles over the mirrors.
     
  6. malibucarl

    malibucarl Member

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    <div class='quotetop'>QUOTE(efusco @ Apr 3 2007, 09:52 AM) [snapback]416972[/snapback]</div>

    How is FM reception with the Shark Fin ??
    Carl
     
  7. darelldd

    darelldd Prius is our Gas Guzzler

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    <div class='quotetop'>QUOTE(malibucarl @ Apr 5 2007, 08:53 AM) [snapback]418259[/snapback]</div>
    Accept, but not as good as the factory antenna. PERFECT for those of us who rarely use the radio. And way the heck better than with a removed factory antenna, like I used to do. :)