Let's Talk Aero

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

  1. Big Black

    Big Black Good, fast<del>, and cheap</del>

    Messages:
    78
    Likes Received:
    60
    Joined:
    Sep 20, 2017
    Location:
    shaking piggy bank in bedroom
    There are no simple answers here, but it might be 'easiest' to reduce lift by dealing with your hood, probably cheaper...anybody smarter than me chip in
     
    Grant 302 likes this.
  2. ChrisM

    ChrisM Do unto others.

    Messages:
    99
    Likes Received:
    86
    Joined:
    May 29, 2017
    Location:
    Japan
    Trackspec Motorsports louvers are a cheap option for hood ventilation. Maybe not as functional as a purpose-built hood, but for something like 1/10 the total cost they're worth it.
     
    VoodooBoss and Big Black like this.
  3. Big Black

    Big Black Good, fast<del>, and cheap</del>

    Messages:
    78
    Likes Received:
    60
    Joined:
    Sep 20, 2017
    Location:
    shaking piggy bank in bedroom
    @RES_22 good take.
     
  4. Grant 302

    Grant 302 OPM Spent: $265,852 Moderator

    Messages:
    4,626
    Likes Received:
    402
    Joined:
    Nov 23, 2011
    Location:
    In the OC
    Great question...I'd rather answer *after* I do more testing!

    But in the interest of testing what I think I know...I'll give a shot at it.

    I think the LS splitter would net more than any vented hood. At 100 mph I'd expect the top of the splitter to have points that are greater than +2.5" w.c. on the top surface and possibly average more than that over the entire surface when considering the low pressure underside, which can be large and somewhat adjustable with ride height.

    The only point I've taken so far on the hood is at the rear side at the bulb seal and measured about -1" w.c. (lift). While this wasn't really near any of the points in question for a vented hood or specifically the Tiger Racing one, I don't think there's enough area to vent a hood to match the potential from the splitter.

    That's my best guess for now, comparing them as single theoretical modifications.

    Thanks, Chris. Gotta credit Ford for sharing that video publicly a while back. They took it down shortly after. I should know, but not certain...I think it's part of the video in the Boss owner's kit.

    That's a big reason why I want to eventually test my mostly stock Boss too. Better understanding should come with more data collecting. At least I hope so!
     
    Fabman likes this.
  5. Grant 302

    Grant 302 OPM Spent: $265,852 Moderator

    Messages:
    4,626
    Likes Received:
    402
    Joined:
    Nov 23, 2011
    Location:
    In the OC
    This is absolutely true. Especially when both of these mods would somewhat work together. The vented hood would help 'protect' the underbody low pressure. And/or the splitter slightly reduces underhood pressures and lift in that area.


    I made one pass in the left hand sweeper. This is what I mean about how the flow changes in a turn.
    [​IMG]

    [​IMG]

    Splitter flow on outside of turn:
    [​IMG]
    I should have backed up for that shot. Just to the right, the droplets were still in place below:
    [​IMG]
    So I'm sure that G forces aren't pushing the droplets around. I dusted this area with some corn starch to show up on video. That was a bust since there was traffic (sub 60mph) where I was trying to make a run on the freeway for the straight line flow. I should probably video using wool tufts next time for both.
     
    Fabman and RES_22 like this.
  6. Cruiserfx

    Cruiserfx TMO Intermediate

    Messages:
    57
    Likes Received:
    28
    Joined:
    Jan 26, 2013
    Location:
    Southern Maryland
    Since I have a Boss, I'm not going to cut the hood. I would have to buy another hood and then add vents to it, which puts me close to the price of a fiberglass tiger hood. I am going to work on building a splitter, like what Swiss Boss did, then potentially complement it with a vented hood if I can find a deal on a GT hood locally. Grant, I like the idea of the vortex generators on the rear and was wondering if you had tried them on the sides of the car/rear window, and what the result were.
     
  7. Grant 302

    Grant 302 OPM Spent: $265,852 Moderator

    Messages:
    4,626
    Likes Received:
    402
    Joined:
    Nov 23, 2011
    Location:
    In the OC
    I've only tried them on the back window so far. Most of the pictures I have are a few pages back in this thread. I haven't quantified any results, but have observed more attached flow on the upper spoiler and wing surfaces. I have tried other arrangements further down the back window with other staggered layouts, but I'm pretty sure I lost all of those in a computer crash.
     
    Cruiserfx likes this.
  8. Grant 302

    Grant 302 OPM Spent: $265,852 Moderator

    Messages:
    4,626
    Likes Received:
    402
    Joined:
    Nov 23, 2011
    Location:
    In the OC
    That's been my plan too. Didn't want to put holes in either original hood.
     
  9. Fabman

    Fabman Project: "Frankenstang"

    Messages:
    1,839
    Likes Received:
    802
    Joined:
    Jan 31, 2016
    Location:
    Pleasanton: 1/2 way between Sonoma and Laguna Seca
    And for my next trick.....I will now attempt to transfer the information in this book into my tiny brain without a net...somebody que the clowns......[​IMG]


    Sent from my iPhone using Tapatalk
     
    Cruiserfx, RES_22 and Grant 302 like this.
  10. Fair

    Fair Go Big or Go Home

    Messages:
    26
    Likes Received:
    13
    Joined:
    Jul 2, 2012
    Location:
    Plano, TX
    Somebody mentioned the TrackSpec louvers, which are becoming popular lately.

    [​IMG]

    One of our customers used these on his C6 Corvette (above) before buying a vented hood (below)

    [​IMG]

    We have done a good bit of aero work on some S197s lately, including updates to Jamie's ST3 Mustang...

    [​IMG]

    He had a very successful rookie year in NASA and took the regional ST3 championship. Car is getting faster and setting class track records, easy to drive, wearing tires perfectly.

    [​IMG]

    After an unfortunate incident with a "gator" at NOLA the front end is undergoing some updates in our shop right now

    [​IMG][​IMG]

    I am going to revive our old S197 build thread soon to show the many changes made to this car over the past 2 years + several other aero tricks and updates to some other S197s.

    [​IMG]

    I've been racing a gutless BMW for 2 years but finally made it fast with some aero updates before the last race. Damn I miss that Coyote V8...
     
  11. Grant 302

    Grant 302 OPM Spent: $265,852 Moderator

    Messages:
    4,626
    Likes Received:
    402
    Joined:
    Nov 23, 2011
    Location:
    In the OC
    All absorbed now, right? You should have taken before/after hat size measurements. :p ;)

    Managed a wool tuft test on the splitter yesterday afternoon.
    Side view so you can see that some of the tufts are raised:
    [​IMG]

    Frame 1:
    [​IMG]
    Frame 2:
    [​IMG]

    Video scrolling roughly between the two frames, goes forward, backward then forward:


    I am accelerating from a stop between Frame 1 and 2 in a 50 mph zone.
    There are 8 tufts in the test:
    1- near the center directly on the splitter and does nothing for all the video taken.
    2- on the splitter near the front just inboard of the stanchion/rod
    3- on the stanchion/rod
    4- raised ~3/4"
    5- raised ~1.5"
    6- on the splitter
    7- raised ~1"
    8- on the splitter most outboard in this test

    I'll post later on my interpretation of what's going on later and follow up with a similar post for the on-ramp to freeway run.
     
    RES_22 and ArizonaBOSS like this.
  12. JAJ

    JAJ TMO Advanced

    Messages:
    158
    Likes Received:
    126
    Joined:
    Mar 28, 2016
    I think you'll get a big effect on lift if you can counter that 1" WC of vacuum somehow. Let's just say that the hood and fender area is about 4' square or so, then 1" WC gives you about 85 pounds of lift. That's a lot.
     
    Grant 302 likes this.
  13. Fabman

    Fabman Project: "Frankenstang"

    Messages:
    1,839
    Likes Received:
    802
    Joined:
    Jan 31, 2016
    Location:
    Pleasanton: 1/2 way between Sonoma and Laguna Seca
    I think my first step will be remembering to bring the book home. Didn’t do me much good last night on my desk at work.


    Sent from my iPhone using Tapatalk
     
    RES_22 likes this.
  14. Grant 302

    Grant 302 OPM Spent: $265,852 Moderator

    Messages:
    4,626
    Likes Received:
    402
    Joined:
    Nov 23, 2011
    Location:
    In the OC
    I agree that's a big target and why most want to reduce it. The main issue is how much surface can you remove and vent before it causes other problems. And we're somewhat limited to only remove after the radiator and before the rear bulb seal, and to leave some in for structural purposes. The good news is that venting up front should reduce that 1" for the area immediately downstream too.

    LOL. Now you gotta sleep at work!
     
    RES_22 likes this.
  15. Fabman

    Fabman Project: "Frankenstang"

    Messages:
    1,839
    Likes Received:
    802
    Joined:
    Jan 31, 2016
    Location:
    Pleasanton: 1/2 way between Sonoma and Laguna Seca
    Been there plenty...I have a big facility here with spare offices...I gave some serious thought to just putting in a shower and moving in.
     
    RES_22 and Grant 302 like this.
  16. 302BOB

    302BOB TMO Addict

    Messages:
    2,427
    Likes Received:
    300
    Joined:
    May 4, 2011
    Location:
    Fairfield County, Connecticut
    Reduced commuting expense/time could justify a workplace upgrade that might include more shuteye as a bonus...;)
     
    Last edited: Nov 16, 2017 at 3:59 PM
  17. Fabman

    Fabman Project: "Frankenstang"

    Messages:
    1,839
    Likes Received:
    802
    Joined:
    Jan 31, 2016
    Location:
    Pleasanton: 1/2 way between Sonoma and Laguna Seca
    I used to live literally 90 seconds from here, so the commute wasn't a big thing.
    Now I live 15 minutes away, time for the turbos to warm up.
    I have a couch and some other stuff in my back office so I have slept here more than once, but it's all about having a shower. I came very close to having my contractor friend make an apartment in here but in the end I decided not to....I had the plans drawn up and everything but if somebody complained I would have to move out of it and tear it all down so the risk just wasn't worth the reward. Now I just use the extra office space to store my race day stuff. $1.50/sq. ft. to store folding chairs and EZ ups lol. Pretty expensive storage space if you look at it like that but I don't need 4 offices and they won't let me tear them out so......
     
  18. 302BOB

    302BOB TMO Addict

    Messages:
    2,427
    Likes Received:
    300
    Joined:
    May 4, 2011
    Location:
    Fairfield County, Connecticut
    Fabman, sounds like you have all the bases covered , except maybe for that shower....perhaps Tymeslayer could help you out with that small detail?....:D
     
  19. Fabman

    Fabman Project: "Frankenstang"

    Messages:
    1,839
    Likes Received:
    802
    Joined:
    Jan 31, 2016
    Location:
    Pleasanton: 1/2 way between Sonoma and Laguna Seca
    I wanted to add a Shower, laundry room and full kitchen. I have a microwave, fridge and sink already plus that end of the building has its own big ass bathroom, plus its all air conditioned which is nice. But none of this is about aero so we should not thread jack this any more...
     
  20. Big Black

    Big Black Good, fast<del>, and cheap</del>

    Messages:
    78
    Likes Received:
    60
    Joined:
    Sep 20, 2017
    Location:
    shaking piggy bank in bedroom
    Terry, Looking forward to your contribution to this thread. "Tricks and updates...YESSSS!
     

Share This Page