Review: Track Spec Hood Louvers

Discussion in 'Corner Carver Racing Tech Discussion' started by Fabman, Feb 16, 2017.

  1. ddd4114

    ddd4114 forum member

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    Yup, it's an AJ Hartman wing. However, it's not his off-the-shelf option for the Mustang:

    [​IMG]

    I was originally going to work with someone to have a custom wing built (reinventing the wheel, I know, long story), but that fell through. Thankfully, AJ's wing was fairly close to what I wanted, and he was a huge help with providing a wing with custom mount placement to work with what I already had designed.
     
  2. Fabman

    Fabman Children Of The Corn

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    Have you run this wing yet?
    I'm wondering if I have enough downforce on the front to match the back.

    [​IMG]
     
  3. ddd4114

    ddd4114 forum member

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    Nope, my first event is this weekend. I'll let you know how it goes.
     
  4. Roadracer350

    Roadracer350 forum member

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    Just wondering why not put them closer to the front of the hood that way you could do a small duct to pull hot air out of the radiator? Car looks great!
     
  5. El_Tortuga

    El_Tortuga forum member

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    They are located back in the low pressure area of the hood. The hood is not flat. Any further forward and they'll be into the downsloping portion that stacks up higher pressure air and they would an air entrance not an exit. Any further back, and they would be into the high pressure that stacks up near the windshield.
     
  6. Fabman

    Fabman Children Of The Corn

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    The sweet spot is from 17" behind the leading edge of the hood to 12" from the base of the windshield.
    As long as you are within that envelope you are good to go.
     
  7. Roadracer350

    Roadracer350 forum member

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    Now is that measurement for the hoods with a hump or the flat hood of the 05-09?
     
  8. Fabman

    Fabman Children Of The Corn

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    I was told that regarding my 05/09 but my bet is probably similar for the later hoods.
    I will check and get back to you.
     
  9. Fabman

    Fabman Children Of The Corn

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    Just checked:
    Same sweet spot for both hoods.
     
  10. o2sys

    o2sys forum member

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    Man the 2010 hood looks sweet with the vents.

    How far off do you think the 2010 hood is fitting on a 05-09???
     
  11. Fabman

    Fabman Children Of The Corn

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  12. ddd4114

    ddd4114 forum member

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    The hood vents worked well this weekend. I compared the data to a similar day last year (ambient temps in the 60's on the same track), and both my coolant and oil temperatures were ~10 degF cooler. I'm sure the splitter helped a bit, but I was also on the gas more per lap due to the extra drag and grip with the aero package. On average, my coolant temperatures this weekend were 210-215 degF, and oil temperatures were in the 260's. I think adding some shrouding to my oil cooler should drop that a bit more. I was still seeing the hood flutter at ~130 mph, so more venting would probably help.

    Regarding the wing - it provides tons of downforce, as you'd assume just by looking at it. I found that 3 deg AoA had good balance at speed by providing slight understeer, and anything more than that would push too much. With 315mm Hoosier R7's and a race weight of ~3750 lb, I was pulling 1.4-1.45g in the high-speed turns (~80 mph). Basic math would suggest I'm producing 400-450 lb of total downforce at those speeds. I have a pretty aggressive splitter (which wasn't even working properly) and plan on doing more front aero work, so with just a basic splitter, I think this rear wing setup would be a bit overkill. Even with the smaller end plates and standard mounting system, you'd be running a small AoA. This would be good because separation will essentially be a non-issue, but it also means you can reduce your drag by getting a wing with smaller chord. You can then, in theory, take advantage of the higher aspect ratio and higher AoA to get better lift/drag for the same total downforce.
     
  13. Roadracer350

    Roadracer350 forum member

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    What about running hood pins like the Aero Catch? That should stop flutter all together.
     
  14. Fabman

    Fabman Children Of The Corn

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    Or 4 hood pins....that works.
     
  15. ddd4114

    ddd4114 forum member

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    I don't really care about the flutter itself; I just care that it suggests there is still high pressure under the hood and that's causing lift.
     
  16. Fabman

    Fabman Children Of The Corn

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    Could be that the leading edge of the hood will act like a little wing in front of the grill and cause some lift there no matter what.

    I'm not an aerodynamic engineer, but I did stay in a Holiday Inn last night.
     
  17. Norm Peterson

    Norm Peterson corner barstool sitter

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    Guessing that vortex shedding is involved.


    Norm
     
  18. ddd4114

    ddd4114 forum member

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    Yeah, it's possible. I suppose I could always add some pressure transducers and take some measurements if I get really curious.
     
  19. Fabman

    Fabman Children Of The Corn

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    Or get hood pins.
    That worked famously for me.
     
  20. Roadracer350

    Roadracer350 forum member

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    That's what I am doing is installing 4 Aero Catches across the front of the hood
     

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