Let's Talk Aero

Discussion in 'Road Racing Forum' started by antman450, Oct 21, 2017.

  1. Olaaf

    Olaaf TMO Intermediate

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    Yes, very very true- many people ignore what happens to the air after the inlet- for example, once it's ducted to the radiator or cooler, what then? What is the exit plan? You still have the same air mass as you did before the inlet, so the outlet is just as important.

    A waterfall style radiator exit is the most ideal situation. If you are willing to cut out the front/top radiator support, lean the rad forward, weld in a support, and make a "waterfall duct" up to the hood, get a small fan or two, some sheet metal fab, you can ensure the rad air gets ducted out of the hood- all GT3 and GTLM cars do this.

    I haven't done the lean forward bit myself (yet), but i moved the water and PS tanks to where the battery used to be located, and re-located the battery to the passenger compartment. Still not much room with the intake elbow and stock radiator position for a waterfall exit, so the next step is cutting and welding.

    As for an oil cooler, you want to place that in front of the radiator if possible, not behind. I personally use an RX-7 oil cooler- easy to get on ebay, and super low profile but really thick and handles alot of cooling load- been running on my 4.6 3v for 4 years with oil temps never above 260, even in very hot ambient conditions and 8 hour long endurance races.
     
  2. Grant 302

    Grant 302 OPM Spent: $328,347 Moderator

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    [​IMG]

    [​IMG]
    [​IMG]

    First thing I notice is that the slice doesn't match the iso view...

    The iso view is of a stockish early S197 with a massive 'box' for the engine. And where are all the elements that are sliced-through in the iso view? And is there a strake-like element behind the rocker panel or not?

    No scale or legend on the pressure plot/slice? I haven't usually seen plots where atmospheric/free stream is red. Low pressures are usually *blue*.

    "a lot" of fender well pressure is relative. A stockish car like shown will certainly have higher pressure at the lower front face of the back of the fender liner.

    Despite the inconsistencies of the presented problem and lack of test parameters, my guess is that 12" downstream most of this flow structure will begin dissipating and its cross sectional 'size' will be smaller and somewhat attached to both the ground and the body panel/door and rocker. It would look like it's tapering down if plotted as an 'isosurface' at the border between say the green/yellow or yellow/red pressure values from your slice. Just my guess, and assuming you aren't using v=mach 1 ;)
     
  3. Grant 302

    Grant 302 OPM Spent: $328,347 Moderator

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    Really? I don't see how you got the nut on the back side of the 5/16" hardware in there, but O.K. :rolleyes:

    Have you seen the surface of the GT350 plastic parts? It's not smooth, and I think that's actually a design element included for its aero properties...

    But either way: No, I don't think it's (skin friction on the skirt/rocker panel) a relevant or significant factor to this discussion regarding downforce and comparing to their removal.
     
  4. Grant 302

    Grant 302 OPM Spent: $328,347 Moderator

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    I liked that post right until I got to this part. Coyote variants generate a lot of heat over the 3V redline. An oil cooler doesn't need 'first air' which would only reduce your cooling capacity for the coolant side. My 2nd oil cooler is in the front too, but given the space and hood vents, I would certainly choose to put a first cooler in the hood vent. Makes more sense thermodynamically on a race car.
     
  5. Badger

    Badger TMO Beginner

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    Edit: Did not realize vented fenders have been a topic here last week. I`m catching up on the thread now. This post has the same topic by pure coincidence, but I guess it plays into it just fine.

    I was digging through vented fenders last night as I am in need for a new fender. But most of them had mixed reviews about their fitment. Then it cam to mind that lots of the track Honda guys just cut their front fenders behind the wheel and fold them inwards. It seams to work well for them and creates and different look.

    So I ended up doing a small mock-up. It´s just an approximation as I do not have a model of the internal structure and thus can´t model around that accordingly. Obviously the rocker panel needs to be squared off or modified in some way.

    Any thoughts on this?

    V1 - low cut
    32471014_10215952643439811_1439086121748267008_n (1).jpg 32549707_10215952658800195_3414460044966625280_n.jpg
    v2 - high cut
    32457331_10215952644399835_5310673589161164800_n.jpg 32655618_10215952650519988_9093238831343206400_o.jpg

    inspiration:
    cut_fender.jpg
     
    Last edited: May 15, 2018
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  6. Grant 302

    Grant 302 OPM Spent: $328,347 Moderator

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    I like it! Just not sure how much it would net you in way of down force or drag reduction!

    The creases from our fenders will be the hardest part of the metal to work and shape inward like that. Might help to make one more horizontal cut at the lower crease and fill-in with gussets to make it all fit.

    Fenders are relatively cheap. Looking forward to pictures if you do it!
     
  7. Busdriver

    Busdriver TMO Intermediate

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    I was thinking of something similar, but cut along the creases and leave the rear portion of the fender arch, then build a "funnel" to go inside the fender to smooth the transition up and out of the wheel well.

    I need an excuse to buy a welder.
     
  8. Grant 302

    Grant 302 OPM Spent: $328,347 Moderator

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    I'd like to do the same, but on some future project car that I don't own yet. But aero-wise still low on the priority list of modifications for me.
     
  9. flyhalf

    flyhalf TMO Intermediate

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    So,
    Let's back to Earth to common humans :)
    I'd like summarize with you so far, the best Objective MODS for DF for a S550 and a S197.
    Now I know it depends on what you want to do with the car , the type of road course etc.
    but,
    If you would pick top 5 (or more ) DF gadget/things/upgrade/however you want to call it
    what would you do?
    I'd like also try to find from 1 to 100 the importance of them.
    i.e.
    splitter 40
    post wing 30
    hood 10
    fenders 5
    diffuser 10
    side skirt 5
    for a total of 100

    THIS IS JUST an EXAMPLE .

    For people not expert like I am ,following this topics is awesome.Learning a lot about the theory behind the Real life.

    although after 16 pages I must admit I think I probrably lost some Info somewhere in the way :)

    @Olaaf , @Grant 302 , @Badger @Busdriver , @VoodooBoss just adding some name to know if you would like to contribute :)

    Fly
     
  10. OCPONY

    OCPONY TMO Intermediate

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    Brian Faessler.jpg
    BRian Faessler car has vented fenders==>
     
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  11. OCPONY

    OCPONY TMO Intermediate

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  12. gripdriver

    gripdriver TMO Advanced

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  13. AJ Hartman

    AJ Hartman TMO Intermediate

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    VoodooBoss likes this.

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