Just Some Aero Questions

[Mad Hatter]

Didn’t you say something like 650/400ish? In that other thread?

People need to consider how much their front suspension compresses in braking and cornering.

I have in burned into my memory that AJ said a good starting point was at 500#/300#... I was at 600#/350# but the change to a softer spring was faster and you can hit the curbs...

 

[Fabman]

I have in burned into my memory that AJ said a good starting point was at 500#/300#... I was at 600#/350# but the change to a softer spring was faster and you can hit the curbs...

Also depends on the amount of aero loading.
A car with less aero (or less effective aero) relies on more mechanical grip, so softer springs and cars with more aero have more downforce which requires more spring to support it.
You want just enough spring to support the aero loading, no more no less> Best of both worlds.

 

[Grant 302]

I have in burned into my memory that AJ said a good starting point was at 500#/300#... I was at 600#/350# but the change to a softer spring was faster and you can hit the curbs...

And that’s a good ‘baseline’ IMO. I remember that too. And that’s optimized for what? 275 DH slicks? But where he might get to with an unrestricted/unlimited aero car...I can’t say. But I know that I could tolerate much more spring than the 550/350 I have on my full weight GT on only 305 DH.

 

[blacksheep-1]

I think that was the " old" grand am base setup with the small splitters and wing, the PWC uses more aero so more spring was needed. You guys need to sticky all that stuff because that was about 150 races ago and it's all I can do to remember what I did last week.

By " seperation" I mean the splitter will try to pull away from the body work, so a good structure and color coordinated racers tape are a must.

 

[Mad Hatter]

Would this qualify as a Big ass wing and splitter? I keep meaning to paint the car and put the Boss stickers on, but something always breaks and takes my paint money away. Maybe I should re-install the 600/350 setup

 

[Grant 302]

Would this qualify as a Big ass wing and splitter? I keep meaning to paint the car and put the Boss stickers on, but something always breaks and takes my paint money away. Maybe I should re-install the 600/350 setup


View attachment 63614

Might be a good time to try. But you haven’t run the Koni DAs yet?

Fuel door open

 

[Mad Hatter]

Might be a good time to try. But you haven’t run the Koni DAs yet?

Fuel door open
View attachment 63616

Just put the Koni DA's in now, have not tried them yet.. And yes the darn fuel door does not shut well after the last big off road trip.... How do you like those silly looking droopy pipes for the sound level... they did shave off a db though.

 

[Grant 302]

How do you like those silly looking droopy pipes for the sound level... they did shave off a db though.

Wasn’t gonna comment cause I know the dingle pipes work.

 

[blacksheep-1]

Looks like an illegal aerodynamic device to me.

 

[Mad Hatter]

The Dingle pipes? They worked wonders in clearing the track of debris, If i point them up I will get more downforce... but sound will go to hell.

 

[blacksheep-1]

OK somebody sticker this before I forget.
Base Mustang S197
3400 - 3500 pounds
limited aero
500 front 300 rear
Ford "Blue" bar up front
18mm bar rear

Mustang S197
3300 pounds ish
max aero
basically a free for all
whatever bar on the front that worked
18mm or no bar on rear

all these depend on the track
all these were on hi zoot Penske shocks (which is really the key to making it work)
these are very base. At some tracks AJ and Kurt were making 25 pound rate changes in practice every few laps and were all over the shock settings and pressures , so your results may vary

I had to ninja edit this as some were incorrect.
In any case, the Penskes are the key to making this work

 

[Mad Hatter]

Pesky Pensks..... Still far out of the budget range . Going to take the 350 rear springs with me and see if we can try them out in the practice lap. Next race is April 15th.

 

[Grant 302]

I liked the pre-edit version of this post better:

OK somebody sticker this before I forget.
Base Mustang S197
3400 - 3500 pounds
limited aero
500 front 300 rear
Ford "Blue" bar up front
18mm bar on rear.

Mustang S197
3400 pounds ish
IMSA style aero
650 front 350 rear
Ford "blue" bar front
18 mm or no bar rear

Mustang S197
3300 pounds ish
max aero
basically a free for all
500 - 350 front (about)
350 - 175 rear (about)
whatever bar on the front that worked
18mm or no bar on rear

all these depend on the track
all these were on hi zoot Penske shocks (which is really the key to making it work)
these are very base. At some tracks AJ and Kurt were making 25 pound rate changes in practice every few laps and were all over the shock settings and pressures , so your results may vary

 

[Grant 302]

Pesky Pensks..... Still far out of the budget range . Going to take the 350 rear springs with me and see if we can try them out in the practice lap. Next race is April 15th.

And dial a bit more squat in!

 

[Mad Hatter]

My squating came to a stop when I was having too much contact with the rear tires... time to re-visit and corner balance again.

 

[AJ Hartman]

Hey! An aero thread! Answers below.

Hey, all! I've been doing some research, planning out my budget for my car, and have decided that instead of trying to find a legitimate, OE Laguna Seca or World Challenge splitter for, I don't know, just south of $1,000, I'm going to make a custom "knock-off" one myself. Now, I have found a thread on this and know what all I need to construct it, but I do have one question for all you Boss folks out there.

Can you use the OE LS splitter rods while using the Boss street splitter as a spacer? I'm trying to judge what length I would need, if another length was needed.

Now onto canards. I know AJ Hartman is, as far as I know, king. I was wondering if anyone had ever attempted to create custom canards (if they would even work?), or if there were any other companies I should look at.

Any opinions welcome, just trying to understand the world of aero a little better. Thanks!

P.S. Yes, I know I left out wings, my car is still primarily a daily driver, and I don't have the energy to deal with all the "RICER!!!" cries I would inevitably deal with. If anyone wants to talk about wings, feel free to. This is not meant to be a just "me" thread, it's for anyone and everyone with aero questions.

Crazy that OEM splitters are that much now. We can do carbon ones, any shape up to 74" wide and 30" deep for less than that. As for your splitter rod question, look at Fully Torqued Racing. High quality rods in any length you want.

Now onto canards, yes, custom canards will most likely do something. All depends on the design. I've seen good ones, I've seen absolutely terrible ones. We have ones chassis specific for several body styles that definitely work. But totally understand people may want to DIY their own.

For the money, I say pass. His are too small to do much of anything. Better off putting the same money toward a vented hood or the wing or fender vents or brake deflectors or just about anything else first.

And I’d plan your wing before anything else. JMO.

Ahhhh, the great aero expert Grant. To small compared to what? All our mustang canards are sized to fit within NASA's American Iron rules, and hence their size. I've seen smaller ones, I've seen larger ones. I forgot you saw all our unreleased CFD and wind tunnel data and been to the wind tunnel with me and know how much downforce our canards make at what speed. The OP asked about canards. Your answer was not helpful.

@Fabman
And others may be able to answer this aero question. What would be the effect of lowering my splitter about 1.5"? The splitter is about 5 inches off the road surface now. Any gains? Any losses?

Doing a bunch of CFD on splitters when we were designing our tunnels, the difference between a splitter at 3" ground clearance made almost double the Df of a splitter at 4". 2" had a slight gain over the 3" ground clearance model, but you gotta start taking into consideration the splitter scraping or hitting things. So essentially the lower the better, to an extent. But 5" off the ground isn't where you want a splitter if you want to get the most performance from it.

And that’s a good ‘baseline’ IMO. I remember that too. And that’s optimized for what? 275 DH slicks? But where he might get to with an unrestricted/unlimited aero car...I can’t say. But I know that I could tolerate much more spring than the 550/350 I have on my full weight GT on only 305 DH.

I'm pretty sure the 550/350 was on my Ai setup when the car was around 2900lbs and wasn't quite enough, but I was still on koni yellows. I then went to 750/450, still on konis. Then when I went to ST2 and did much more aero, I went to 950/550 (I think?) and went to MCS double adjustables. Then when I S550 rear subframe swapped my car I kept the fronts at 950 and the rears I think are 900 now? I changed springs so many times I forget.

 

[Fabman]

Hey! An aero thread! Answers below.

Crazy that OEM splitters are that much now. We can do carbon ones, any shape up to 74" wide and 30" deep for less than that. As for your splitter rod question, look at Fully Torqued Racing. High quality rods in any length you want.

Now onto canards, yes, custom canards will most likely do something. All depends on the design. I've seen good ones, I've seen absolutely terrible ones. We have ones chassis specific for several body styles that definitely work. But totally understand people may want to DIY their own.


Ahhhh, the great aero expert Grant. To small compared to what? All our mustang canards are sized to fit within NASA's American Iron rules, and hence their size. I've seen smaller ones, I've seen larger ones. I forgot you saw all our unreleased CFD and wind tunnel data and been to the wind tunnel with me and know how much downforce our canards make at what speed. The OP asked about canards. Your answer was not helpful.


Doing a bunch of CFD on splitters when we were designing our tunnels, the difference between a splitter at 3" ground clearance made almost double the Df of a splitter at 4". 2" had a slight gain over the 3" ground clearance model, but you gotta start taking into consideration the splitter scraping or hitting things. So essentially the lower the better, to an extent. But 5" off the ground isn't where you want a splitter if you want to get the most performance from it.

I'm pretty sure the 550/350 was on my Ai setup when the car was around 2900lbs and wasn't quite enough, but I was still on koni yellows. I then went to 750/450, still on konis. Then when I went to ST2 and did much more aero, I went to 950/550 (I think?) and went to MCS double adjustables. Then when I S550 rear subframe swapped my car I kept the fronts at 950 and the rears I think are 900 now? I changed springs so many times I forget.

Your original AI trim was 550/300 then you went to 750/400 with the big aero and then added 800# or 850# rears for the IRS.
This is according to the videos posted. Any changes made outside of those I am not aware of.

 

[Grant 302]

Doing a bunch of CFD on splitters when we were designing our tunnels, the difference between a splitter at 3" ground clearance made almost double the Df of a splitter at 4". 2" had a slight gain over the 3" ground clearance model, but you gotta start taking into consideration the splitter scraping or hitting things. So essentially the lower the better, to an extent. But 5" off the ground isn't where you want a splitter if you want to get the most performance from it.

Tunnels that you don’t provide any DF data for? Your responses are also lacking in any DF numbers. I’ve already said your canards for S197 make in the order of less than 10 lbs. each at 100 mph. I’ll add: even less than that in the set of 4 for the ‘13-‘14 style.

 

[Grant 302]

I'm pretty sure the 550/350 was on my Ai setup when the car was around 2900lbs and wasn't quite enough, but I was still on koni yellows. I then went to 750/450, still on konis. Then when I went to ST2 and did much more aero, I went to 950/550 (I think?) and went to MCS double adjustables. Then when I S550 rear subframe swapped my car I kept the fronts at 950 and the rears I think are 900 now? I changed springs so many times I forget.

That’s S197 we were talking about. I think your numbers are a bit irrelevant, but whatever.

 

[AJ Hartman]

Your original AI trim was 550/300 then you went to 750/400 with the big aero and then added 800# or 850# rears for the IRS.
This is according to the videos posted. Any changes made outside of those I am not aware of.

Dang. You know better than I do. That sounds about right.

Tunnels that you don’t provide any DF data for? Your responses are also lacking in any DF numbers. I’ve already said your canards for S197 make in the order of less than 10 lbs. each at 100 mph. I’ll add: even less than that in the set of 4 for the ‘13-‘14 style.

Right in our blog on our website for all to see. Thanks for asking. https://ajhartmanaero.com/blog/project-crusher-part-3/
Also, your guess of 10lbs each is somewhat close, but also way off depending on the setup. Thats why my posts lack in numbers, but guide in the right direction. A set of 4 canards on the E36 made 46lbs in the tunnel. A set of just uppers on my car in the tunnel made 38. Why did only 2 canards on my car make almost as much on the E36? The splitters were way different, and since canards work in conjunction with a splitter, the have an affect on eachother. We also need to take into account the leverage ratio of where this downforce is made since E36's have short noses, and my mustang has a longer nose. If people don't take this into account, they may just see a number I give out there and assume their results would be the same.

That’s S197 we were talking about. I think your numbers are a bit irrelevant, but whatever.

Your response was to a quote where the person mentioned my car.