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Has anyone played with rear diffuser fins - like the Elise

Discussion in 'Roadster' started by wiztecy, Apr 18, 2014.

  1. wiztecy

    wiztecy Active Member

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    #1 wiztecy, Apr 18, 2014
    Last edited by a moderator: Mar 13, 2016
    Has anyone played with the idea of putting on rear diffuser fins on their Roadster like the Lotus Elise / Exige? Any idea why Tesla didn't go that route? When I look at the rear of the Roadster something doesn't look functionally right and appears as if something is missing, I think this is it... It's suppose to help reduce drag which I think would be key for an EV. Might be a fun mod to do. My guess is that it channels air flow backwards and limits side to side channeling which covers a larger area and gives a higher drag coefficient. Also as the DiFlow video shows, extending it further from the rear line of the car keeps the sticky turbulent air away from the vertical rear plane.

    Just looked at the Model-S and it appears it has 4 fins on the rear diffuser which act as channels.

    railerjr_2.jpg




    Even the Nissan Leaf has one!!!

    nissan-leaf-rear-no-tailpipe.jpeg

    aero.jpg
     
  2. wiztecy

    wiztecy Active Member

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    #2 wiztecy, Apr 18, 2014
    Last edited: Apr 18, 2014
    I just sent DiFlow a message to see if they'd be interested in fabricating a rear diffuser for the Roadster. Possibly others would be interested? I want to replace the 1.5 rear aluminum plate, the two crappy useless diffusers on each side with one that has the same look and aggressiveness as the black one from DiFlow above. Also I want it to extend out so it really works on pushing the airflow away from the back of the car. The one above is about $500 or so, which is not all that bad for a custom aluminum performance part.
     
  3. Jaff

    Jaff Active Member

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    A question wiztecy...is the rear diffuser on the 1.5 the same as the 2.0 & 2.5's?

    The diffuser in the vid looks very effective, but, imo, has a face "only mother could love"...I would be interested in a higher performance rear diffuser than the stock one on my 2.5, but I am only willing to sacrifice "so much" with respect to the look on the car...and, I would want it to be CF, not steel or aluminum.
     
  4. Botbldr45

    Botbldr45 Member

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    +1 on comment made by Jaff
     
  5. wiztecy

    wiztecy Active Member

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    #5 wiztecy, Apr 20, 2014
    Last edited: Apr 20, 2014
    I love the mother comment :)

    When I talk to them I'll ask if they can toned down the aggressive look. I'm sure they can taylor it rather easy. I looked at the Evora and it doesn't come out as far off the back end. I'd want it to push away from the rear some.

    As for the CF build of it, I'd be afraid its too fragile. At least for me. The first drop of the rear or curb would damage it really well I'd feel. It look great, especially if it wasn't aggressive.

    As for the rear diffusers. The 1.5 and 2.0 Roadsters have the same front nose and rear diffusers. The 2.5 has a more sporty one where they eliminated the mesh fill in screen and instead tucked the diffuser up to the rear bumper cover. I believe all the bolt holes are there and the same. People have mounted 2.5 diffusers on the 1.5/2.0 cars.

    One could also make their own channeling fins and mount them under the 1.5's rear pan/diffuser. There's rows of bolts that will work nicely as a mounting points for the fins. I originally was thinking about that. But the extension out the rear is a large functional part of getting the draggy air away from the car.

    I've also seen on a few Lotus Elise posts where they put a nose lip on the front, where some say it lowers the drag but also creates more down force on the front for traction. It appears the 2.5 has this design added to it that the 1.5/2.0's were lacking:

    APR Performance - Lotus Exige Front Air Dam

    IMG_1080.jpg
     
  6. Jaff

    Jaff Active Member

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    Actually, I would have no problem with the CF with respect to durability...I have a CF lip on my Roadster (2.5)...drive it 24 / 7 all year round through the snow & ice...have over 70,000 kms on the car, and nary a chip on it...I think a CF diffuser would look great and hold up just fine...jmo
     
  7. hcsharp

    hcsharp Active Member

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    Agree. CF would be stronger and more durable than aluminum. It would also weigh less and look better.
     

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