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How far should my front splitter protrude past the air dam if I have the Blackbird Fabworx spoiler in the rear?
~250 WHP
245 Rival S
Autocross Application
The advice i got from some SCCA guys was 3-4" and the splitter near vertical. For track, I'm following Emilio's advice of airdam/undertry only and haven't built an autocross version for my car yet, so YMMV.
How far should my front splitter protrude past the air dam if I have the Blackbird Fabworx spoiler in the rear?
~250 WHP
245 Rival S
Autocross Application
I had a 4" splitter on 245 RS4, Xidas, etc and could NOT get the car aero balanced while running the BFW spoiler regardless how many adjustments I tried. I had exit oversteer. This year I switched to the NLR wing and all those problems are gone.
While this is not really "aero" directly, I wanted to post this here because it is aero impacted and I have come to really respect the ideas/options in this thread.
I have a need to place an auxiliary coolant heat exchanger in my system due to the rear mount turbo. Last track day saw temps hitting 260 when pushing it hard in the heat of the TX sun.
I have 2 options I am looking at for placement and I'd like to get some input.
1. In the duck bill lid like a Porche
2. Where the license plate is at.
I plan to run a GT-250 wing so unsure how that would impact option 1 and not a huge fan of cutting into my fastback but I think it would look good.
Fans will be wired in reverse for both options so the fans are inside the trunk and will force air out of the lid or plate area.
Thanks to this thread, I am also currently building a front air dam and splitter to hopefully balance out the rear wing. (Will trim the splitter to match the final shape of the air dam)
DIY Naca ducts 3d printed, flush mounted in the birch ply splitter floor and feeding 3" hose feeding to the rotor/hub area. Not tested yet to prove it, but along with brake cooling this may even help with extra front downforce.
I designed the ducts myself in Fuision360, and sort of 'winged' the shape (pun intended) so I cannot know for sure if it will work. If you're interested, plenty more details on the car here: www.youtube.com/bbeavis
Dollars spent: ~$10 for the ducts Hours spent: 2hrs to design duct, 1.5days to 3d print, ~4hrs to cut/glue into the splitter and attach hoses. How effective: testing next weekend... Materials used: PLA plastic ducts, 3" hose, zip ties to secure hose to car.
Interested to hear how the undertray Naca brake duct worked out?
While this is not really "aero" directly, I wanted to post this here because it is aero impacted and I have come to really respect the ideas/options in this thread.
I have a need to place an auxiliary coolant heat exchanger in my system due to the rear mount turbo. Last track day saw temps hitting 260 when pushing it hard in the heat of the TX sun.
Vegas has the best setup I've seen for a rear mounted heat exchanger. Take the high pressure wheel well air and duct it into the low pressure license plate area. Should provide a small lift reduction with minimal drag penalty.
Ha... what do ya know! 2 birds with one stone and I can mount it so the fans draw air the way they were designed to rather than push. I recall seeing a post where a guy ran ducts to the backup light holes he broke out. Good idea but the license plate spot just looked "right" to me. Glad to see someone else thought the same. Thanks for the link!
DIY Naca ducts 3d printed, flush mounted in the birch ply splitter floor and feeding 3" hose feeding to the rotor/hub area. Not tested yet to prove it, but along with brake cooling this may even help with extra front downforce.
I designed the ducts myself in Fuision360, and sort of 'winged' the shape (pun intended) so I cannot know for sure if it will work. Dollars spent: ~$10 for the ducts Hours spent: 2hrs to design duct, 1.5days to 3d print, ~4hrs to cut/glue into the splitter and attach hoses. How effective: testing next weekend... Materials used: PLA plastic ducts, 3" hose, zip ties to secure hose to car.
Interested to hear how the undertray Naca brake duct worked out?
Not definitive yet, and unfortunately I didn't measure *before* temps. (I monitor caliper temp now though.)
The brakes worked ok at the last event, but still suffer from heat after about 4 hard laps. I want to add a form of backing/duct to feed the air better at the hub, but that'll take some engineering.
Either my driving style / power level / grip levels are too much for the brakes now, or Wilwoods just aren't good enough.
Not definitive yet, and unfortunately I didn't measure *before* temps. (I monitor caliper temp now though.)
The brakes worked ok at the last event, but still suffer from heat after about 4 hard laps. I want to add a form of backing/duct to feed the air better at the hub, but that'll take some engineering.
Either my driving style / power level / grip levels are too much for the brakes now, or Wilwoods just aren't good enough.
Interested in your continued testing of this. Did you have ducted brakes before? Is there a reason you chose the splitter bottom over the front fascia? You should be able to get much higher pressure from the fascia.
Neither actually. I have the Dynapro kit from Trackspeed. Sadly the Superlite option didn't exist when I purchased them.
Originally Posted by nick_deno
Did you have ducted brakes before? Is there a reason you chose the splitter bottom over the front fascia? You should be able to get much higher pressure from the fascia.
No ducts previously (in this iteration of the cars setup). I wanted to try something different, and try keep an efficient and low drag front... and I don't like holes in the front bumper of the car. I can just iteratively test different things until I get something I like.
Neither actually. I have the Dynapro kit from Trackspeed. Sadly the Superlite option didn't exist when I purchased them.
No ducts previously (in this iteration of the cars setup). I wanted to try something different, and try keep an efficient and low drag front... and I don't like holes in the front bumper of the car. I can just iteratively test different things until I get something I like.
One of my off season project is to add a bit of front / rear aero to my car. Figure I would post here as I got a lot of inspirations from this thread.
This is a rough start of the 'street / track / have fun' version with 3" of protrusion from the tip of the hood. The 'autox' version will be mostly the same though wider to incorporate some fenders to flow air over the wheels. Maybe protrude up to 6" ( class limit ).
For now, I kind of like how it looks with the "big mouth" large front opening but .. am debating if I should try to reduce the height of the front opening a bit ( and blend it back to the bumper ) to help reduce drags since I don't currently have any cooling issues.
Also feel free to throw out suggestions for improvements.
Smarter people than me will correct this but I think the rough rule of thumb (with proper ducting) is the opening can be 1/3 the frontal area of the heat exchanger (rad/intercooler etc) size. Possibly even less?
You will have HUGE drag (and likely lift) issues at medium and up speeds like that currently.....
My friend builds and tunes these mx5 derivative type cars and he tops out speed wise very easy with drag (nose, uncovered wheels and so on) even with the proper nose...
I've been considering whipping up a wing setup for my car, and an end plate mounted wing came to mind, since big end plates seem to help with efficiency and normal uprights disrupt flow.
Is there a good reason why they're not used in GT cars or other racing? It's prevalent in F1 , but I wasn't sure if that was due to a restriction on F1s side, or a restriction in other race classes. the NOPRO guys used it on their GT300 car, but that wasn't exactly a winning car.
Smarter people than me will correct this but I think the rough rule of thumb (with proper ducting) is the opening can be 1/3 the frontal area of the heat exchanger (rad/intercooler etc) size. Possibly even less?
You will have HUGE drag (and likely lift) issues at medium and up speeds like that currently.....
My friend builds and tunes these mx5 derivative type cars and he tops out speed wise very easy with drag (nose, uncovered wheels and so on) even with the proper nose...
You're right about that the drag. These cars are kind really bricks over 80mph. The best thing to do aero wise would probably be putting the Miata body back on. Luckily my main game is autox so most of the time I'm under 100. That said I have an idea for a revision that will reduce the frontal area more and will start work on that.
Could you point out where you're thinking the lift could be created ?
06-03-2019, 01:46 PM
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