• Welcome to SVTPerformance!

Aerodynamics for high speeds

Discussion in 'Open Track Racing' started by N/Angel, Oct 17, 2016.

  1. racebronco2

    racebronco2 Active Member Established Member

    Messages:
    7,266
    Joined:
    Sep 23, 2003
    Location:
    palmdale, ca
    Not very effective,
    1. The angle you need the diffuser to rise with no turbulence is around 15 degrees.
    2. You must have clean air channeled to the diffuser.
    3. The diffuser need to start at the lowest rear portion of the car.

    I had one on my car which i designer properly. It started slightly lower than the exhaust and was flat with the bottom of the car. At the rear of the car i made a piece that extends the rear of the bumper cover a few inches so that the diffuser was only 15 degrees. I removed it because it was really hard to work on the suspension, load the car on the trailer without the fins hitting the ground. Did it make a difference, i couldn't tell because the underside of the car was not paneled in.
     
  2. FoMoCo01

    FoMoCo01 Member Established Member

    Messages:
    70
    Joined:
    Aug 28, 2011
    Location:
    Arvada, Co
    That is a show piece. If you were going to run a rear diffuser like that, you would want the front of the diffuser to be completely sealed to the body and you would want a 7-10 degree angle in the diffuser instead of the large angle of the one shown. Better yet would be to make the underside of the car completely smooth and flat. It also depends on how fast you're going. If you're 120+ you want to start looking into reducing drag and adding some downforce to keep the car stable at higher speeds. Look into the rear spoilers that drag racers or nascar use use. Stay away from wings as they will add too much drag. They will offer the most benefit along with some some rear to front rake.
     
  3. iismet

    iismet Member Established Member

    Messages:
    206
    Joined:
    Feb 26, 2004
    Location:
    Portland Oregon
    +1

    [​IMG]

    You can just see the bottom of the exhaust - that is how low the floor is. I have checked mine several times with a level. We plan to build the ceiling @ 8 degrees. At 8 degrees from the floor there is a gap between the bottom of the bumper and the ceiling of the diffuser - that is how low the diffuser has to be. If he were to to sheet the bottom, lower the diffuser, correct the ceiling angle, he would want to push it back so it's trailing edge intersected the vertical plane established with the trailing edge of the spoiler. Also the outer strakes are too far inboard. Their job is to seal wheel well pressure out out of the diffuser.

    The goal is to build a venturi with the area between the ground and bottom sheeting acting as the venturi throat.

    With a dirty bottom he is dragging dirty air which creates lift.

    Stolen for reference

    [​IMG]

    [​IMG]

    [​IMG]
     
    FoMoCo01 and WHT03SVTCOLO like this.
  4. iismet

    iismet Member Established Member

    Messages:
    206
    Joined:
    Feb 26, 2004
    Location:
    Portland Oregon
    [​IMG]

    chr
     
  5. iismet

    iismet Member Established Member

    Messages:
    206
    Joined:
    Feb 26, 2004
    Location:
    Portland Oregon
    [​IMG]
     
  6. N/Angel

    N/Angel crazy Swiss Chick! Established Member

    Messages:
    2,556
    Joined:
    Apr 4, 2006
    Location:
    Switzerland/Germany
    just out of curiosity, anyone have a functional diffusor installed?
     
  7. WHT03SVTCOLO

    WHT03SVTCOLO Member Established Member

    Messages:
    549
    Joined:
    Oct 5, 2006
    Location:
    Colorado
    How does the apr stuff stack up for aerodynamics for high speeds? I'm looking to improve my 11 top speed. Maier racing doesn't have anything for us 10-12 mustang.

    http://aprperformance.com/racing-product/widebody-aerodynamic-kits/
     
  8. racebronco2

    racebronco2 Active Member Established Member

    Messages:
    7,266
    Joined:
    Sep 23, 2003
    Location:
    palmdale, ca
    Diffusor are not street or working on the car friendly. I built one with the correct specs. I could not tell any improvement in the car with it installed. I think there was no improvement because the whole under body needs to be smoothed out to direct the air correctly. The fins were so low it was hard to adjust the rear suspension. i could barely rear the toe links. The car would scrap sometimes on steep driveways. I used to open track alot and sometime i had to be towed home. There is no way the car could be put on a flatbed backwards, putting the car on a flatbed front first we had to use 2 x 4's in front of the rear wheels so that the diffusor wouldn't scrape so much.
     
  9. noldevin

    noldevin Active Member Established Member

    Messages:
    720
    Joined:
    Sep 7, 2014
    Location:
    New Jersey
    Sounds like a lot of pain in the ass for little or no gain.
    Sadly the underside of these cars is just too messy to get a good rear diffuser set up.
    I have wondered if those RTR vented inserts next to the rear license plate actually make any difference.
     
  10. N/Angel

    N/Angel crazy Swiss Chick! Established Member

    Messages:
    2,556
    Joined:
    Apr 4, 2006
    Location:
    Switzerland/Germany
    blowing the light dust of this thread... been working on the engine a bit more and got it to 496hp at the crank, 500hp is the limit in my class.
    Last event was great, got second place in front of Golf 7R, AMG C63, M2, M3 Competition, Alpina... only the one C7 Vette was faster.
    I passed the line at 246,59kph, he is at 249,71kph. Cars in my class going faster than the 250kph limit automatically are moved to the next higher class.

    So I'm trying to find the missing 3kph for the next event in July, the M3 got really close in the last run!
    My mods sofar: Coyote engine, Magnum 6-speed, 3.73 IRS, Racebronco hood, gutted interior with rollcage (dash, door panels and corbeau seats), battery moved to the trunk, 18" Wedsport wheels.
    Things I already have on the to do list:
    - run with below half tank of gas! (full the last time)
    - tape up my Agent47 Side window scoops
    - fold in the mirrors

    Any other suggestions?
    I would like to get rid of the stock door panels but can't seem to find a carbon fiber replacement. Probably not much for weight savings but every little bit helps.

    Here is a pic of the car at the last event
    IMG_3542_small.jpg
     
    03 DSG Snake and 98 svt like this.
  11. racebronco2

    racebronco2 Active Member Established Member

    Messages:
    7,266
    Joined:
    Sep 23, 2003
    Location:
    palmdale, ca
    Inflate your tires to the max, If you radiator is boxed in remove the bottom panel.
     
    N/Angel likes this.
  12. 03 DSG Snake

    03 DSG Snake Unknown Cyborg Established Member

    Messages:
    20,655
    Joined:
    Nov 3, 2002
    Location:
    CA
    Ultra-Carbon '99-'04 Ford Mustang Parts | Ultra-Carbon

    SN95 99-04 Doors
     
  13. BlackStripes

    BlackStripes Member Established Member

    Messages:
    427
    Joined:
    Feb 26, 2003
    Location:
    Fairfax, VA
    I'd cover the area where the pony is, our cars can get all the air from the bottom opening.

    I spoke with AJ (rhrperf) several months ago and his doors are for RACING.... they are only a little piece of carbon :) ( I have their trunk)

    And I also was talking to Greg Shampine (Ultra Carbon owner), since I heard from friends that his products are outstanding, but he raised his price from $2800 to $3800 in matter of 3 months ... I stopped talking right there ;)

    Seems like you want only the panels, which, you are right, I can't see that saving more than a couple of lbs. The doors though, they save over 65lbs (both). I am getting a set, but waiting to find the right time/company.
     

    Attached Files:

    03 DSG Snake likes this.
  14. N/Angel

    N/Angel crazy Swiss Chick! Established Member

    Messages:
    2,556
    Joined:
    Apr 4, 2006
    Location:
    Switzerland/Germany
    I usually run 3 bar tire pressure front and back. Even higher?
    I'm also looking at a set of semislicks for my 9x17 Wedsports. Maybe run 245/40/17 all around if traction is no issue.

    Radiator is not boxed in
     
  15. N/Angel

    N/Angel crazy Swiss Chick! Established Member

    Messages:
    2,556
    Joined:
    Apr 4, 2006
    Location:
    Switzerland/Germany
    is covering the area where the pony is really not hurting cooling? I remember the FR500 had the hood extended to cover this area, but it wasn't a production car.

    I would love to get a set of doors, but the cost is insane and it will never be TÜV approved, I'm in Europe. This is why I'm looking for the panels only, something like Agent47 had a couple of years back, just in carbon fiber.

    Cost is a real issue as I'm trying to put money aside for a sequential transmission and maybe a supercharger setup next year.

    and just to make things more interesting, a Ferrari F430 signed up for the July race and sits at the same powerlevel as mine. How on earth can I beat a Ferrari!?!? LOL!
     
  16. BlackStripes

    BlackStripes Member Established Member

    Messages:
    427
    Joined:
    Feb 26, 2003
    Location:
    Fairfax, VA
    1174655_616945858396751_5602956704531435672_n.jpg AJFrontEnd.jpg
    A lot of American Iron (X) cover the front area, as long you open up the bottom, you should be ok. You have a real water/oil temp gauge?
     
  17. racebronco2

    racebronco2 Active Member Established Member

    Messages:
    7,266
    Joined:
    Sep 23, 2003
    Location:
    palmdale, ca
    I did a test years ago with yard and a camera because i heard the same thing. The results is that our cars do not get any air from the boom below the bumper cover. Think about it, you are doing 100mph, the air is not going to slow down to make a 90 degree turn up and another 90 degree up from 2 inches to 14 inches to the top of the radiator. Our bumper cover forces the air down to clear the radiator support.
     
  18. BlackStripes

    BlackStripes Member Established Member

    Messages:
    427
    Joined:
    Feb 26, 2003
    Location:
    Fairfax, VA
    Not sure about that, there is air that touches the car for first time at the bumper (i guess around 4 or 5 inches) but there's also air that touches the car for first time right at the pony height, and that air will try to go to the radiator instead going up the hood, if you have enough opening at the low side I think you should be ok. If it's a car that is not concern about street driving, i'd cover that section. I've seen enough cars that cover that area in AI/X.

    Possibly the best aero company in my opinion that works on Mustang sells this for that reason:

    SN95 99-04 Cobra R Bumper

    edit: ooops I referenced this a post ago :)
     
  19. 302blown

    302blown New Member

    Messages:
    2
    Joined:
    Apr 1, 2019
    Location:
    Central, NJ
    This post is a little old but the key to any sort of rolling top speed event is lowering drag. Now if the speeds are up there a little bit to downforce, a little, may help with stability at speed. As mentioned in a previous post sealing up the entire grill opening where the pony is will certainly help reduce drag and increase top speed. These extractors are designed to allow reducing the front grill opening, this reduces drag while still maintaining cooling. This was confirmed in wind tunnel testing. www.racelouvers.com
     
  20. N/Angel

    N/Angel crazy Swiss Chick! Established Member

    Messages:
    2,556
    Joined:
    Apr 4, 2006
    Location:
    Switzerland/Germany
    My hood has this kind of louvers.

    I bought another Mustang so budget on this one is tight, currently searching for semislicks for my 9x17 Wedsport wheels, narrowing the tire width should help a bit with top speed.
     

Share This Page