Big Wings: Helpful or hurtful? What's your opinion?

[MineralWhiteF80]

To people with big wings on your realistic e9x track cars:

What made you choose a big rear wing, what were your expectations, and how did it actually affect your car's behavior?

I'm trying to build an informed opinion before simply nailing a big wing to the back of my track car with the expectation of better high speed stability. Unfortunately, there isn't a lot of factual data out there that you can use.

I see a lot of 'normal' track day cars and almost every e92 that circles the Nordschleife running big rear wings (bigger than the OEM GT4 or GTS wings). With the large number of big rear wings, you see almost 99% of people either running no front aero, a GT4 front lip/canards (which I don't think counts as aero but looks sweet), or a slightly more aggressive version of a GT4 lip or APR flat carbon sheet/stanchions below it. The remaining 1% are running some super aggressive Time Attack crazy setup that requires you to have an FAA 141 license. I see this on other car brands too, most cars aren't running crazy front aero yet most people have a big wing. Are the 99% just uninformed and negatively affecting their car's performance because people think "big wings make you faster" or is it a generally accepted understanding that big wings benefits outweigh the negatives?

My car's basic setup is Nitron R1 (700F/1000R springs), 18x10 wheels with 275/35/18 tires, and the GT4 front lip/canards with function brake ducting (and because it looks awesome). My car's balance and general behavior only moves toward oversteer when pushed harder. I've never had the car understeer one single time under normal track conditions, and Im usually anticipating the rear end wanting to step out. Im wondering if a rear wing of some sort can help me get back to more neutral handling while increasing high speed stability in turns between 110-140+ mph.

I see a couple of 'tried and true' options that I think are considered acceptable and are either tested by BMW or a reputable race team with lots of on track experience, but what happens when we get into the big, BIG wings that are mostly universal fitment?
- OEM GTS front lip/GTS wing
- OEM GT4 front lip/canards/GT4 wing
- Bimmerworld front lip/canards/wing

[JobanM]

Drove the car without aero for a year. Recently even tested out the car without aero on a slow speed circuit. The car is more fun without aero as it dances around, but it’s not fast.

I do think the GT4 front lip and wing would help regardless since the stock car is creating significant lift. I think there is an article somewhere with the GTS wing and the stock car.

I run the APR250 67 inch and honestly sure some people look at like what is this clown doing, but there are zero downsides on the road. It sits so high that I don’t even notice it in my rear view mirror. As for effectiveness it works so well even at low speeds where you don’t think it would. Even at speeds around 80km/h the car is more stable. I do have it paired up with the Zebulon front splitter 6 inch one which in hindsight I should have probably settled for shorter 5 inch version.

That does limit your use on the road, but it’s extremely easy to remove. I don’t take it off as I just take it to work and my friends house. Although the worst case you just hit your skid blocks which I don’t care as I just replace them once they wear.

You can ask Zebulon to make a custom one as well maybe a 4 inch would be better. Any of the big wings do require a chassis mounted splitter to balance the GT4 lip isn’t really going to balance the rear. You will most likely end up with understeer at high speeds.

[omgzirra_exe]

Personally, I'll be running a GT4 lip with my newly acquired 62-inch wing, with the total height just under or at the roofline, so we'll see how that goes. might be a bit of understeer or i crash and burn.

[roastbeef]

there was a thread a while back discussing the gts wing on our cars. the general consensus was they are useless as an airfoil, but are commonly used at a high angle that they work as a spoiler. any wing that short and at that high of an angle would be stalled anyways.

couple quick points;
-you can run a very large wing at a lower angle to create more downforce with less drag than a smaller wing with more angle.
-while a lower wing isn't useless, roofline height is ideal.
-gurney flaps can augment a smaller wing by creating a longer separation of airflow, but the trade off is more drag. gurney flaps are more common to see on wing dimensions that are limited by class.

[BoilerUP]

A 61" GT250 has modest downforce would likely balance well with the GT4 front lip at 0 AOA without gurney strip. You could always add gurney and/or AOA as desired for more rear downforce.

[bbnks2]

Originally Posted by roastbeef

couple quick points;
-you can run a very large wing at a lower angle to create more downforce with less drag than a smaller wing with more angle.
-while a lower wing isn't useless, roofline height is ideal.
-gurney flaps can augment a smaller wing by creating a longer separation of airflow, but the trade off is more drag. gurney flaps are more common to see on wing dimensions that are limited by class.

This! I run the GTC250 67" wing which is massive and I have it set around a modest 3* aoa. I did make a 5" splitter out of plywood also set to 3* rake to help balance it.

GTS wing isn't useless. The front aero is lacking because of class rules not because the rear wing doesn't do much. So yeah, it's more a case of "the benefits outweigh the negatives." If I have the choice then I wouldn't run a big rear wing with no front aero... why would you?

[tsk94]

I think they help, with almost no downside.
You'll want to set your AOA to compliment your front aero, but otherwise, they only help. In my experience, they provided more rear-end stability in both medium and high-speed corner and better braking stability. It did cause more understeer, so I did tweak my setup slightly to help.

[DrFerry]

Sorry, couldn't help but cross-thread this topic.
.
https://www.m3post.com/forums/showthread.php?t=1794400
.

.

[omgzirra_exe]

Originally Posted by DrFerry

Sorry, couldn't help but cross-thread this topic.
.
https://www.m3post.com/forums/showthread.php?t=1794400
.

.

the fact that thread brought back some un wanted memories i will share here..

[DRLane]

Originally Posted by omgzirra_exe

the fact that thread brought back some un wanted memories i will share here..

Except that aero setup I believe worked. That reference below is just 🫣

[DRLane]

Originally Posted by tsk94

I think they help, with almost no downside.
You'll want to set your AOA to compliment your front aero, but otherwise, they only help. In my experience, they provided more rear-end stability in both medium and high-speed corner and better braking stability. It did cause more understeer, so I did tweak my setup slightly to help.

Pics (or better yet the build thread) or it didn’t happen!

In all seriousness, now that you’re back from f8x land can we expect a new thread for this go around?

[tsk94]

Originally Posted by DRLane

Pics (or better yet the build thread) or it didn’t happen!

In all seriousness, now that you’re back from f8x land can we expect a new thread for this go around?

Maybe...

This time around it might be a little more interesting as it would actually document the 'build' as it progresses, rather then after everything was done. But it would be a fairly standard track build this time, not a gutted race car. There's a lot of good build threads now, so not sure if another from me would bring anything to the table, lol.
I've been busy building an E36, so E92 will probably start around spring/summer 2024.

[DRLane]

Originally Posted by tsk94

Maybe...

This time around it might be a little more interesting as it would actually document the 'build' as it progresses, rather then after everything was done. But it would be a fairly standard track build this time, not a gutted race car. There's a lot of good build threads now, so not sure if another from me would bring anything to the table, lol.
I've been busy building an E36, so E92 will probably start around spring/summer 2024.

I’m in the, release my gutted race build when it’s done vs progress. Mostly because I don’t want a bunch of “you can’t do that” perspectives 🫡

Excited to see what you cook up!

[MineralWhiteF80]

Originally Posted by DrFerry

Sorry, couldn't help but cross-thread this topic.
.
https://www.m3post.com/forums/showthread.php?t=1794400
.

.

THANK YOU. Thats what I was looking for because I only remembered seeing a thread with a white car with the most amazing front aero ever , and could not find it.

[MineralWhiteF80]

and if any of you are wondering, here is my current highly aggressive rear aero setup

[bigjae1976]

I'm not saying my approach is right but looking back I think it worked really well on my E46

I got the car to my liking in stock form - no aero mods. Or at least I'd say drive it and get to know it. This establishes a baseline, at least in my mind it does. Then I've been adding stuff.

I'd say you need to buy more wing than you think you need and go with a wing that's been tested on the car.

You might be OK with a GTS wing and a good rear diffuser. In some cases, a high kick trunk lid can help with extraction from a diffuser which would add downforce...more diffuser extraction will speed up air flow and lower pressures under the car. Then if you improve airflow under the lip towards the back then you should see more rear downforce gains.

But bolting a wing on the rear trunk would be much easier.

Originally Posted by DRLane

Except that aero setup I believe worked. That reference below is just 🫣

Greg Smith...really smart dude. He solved the E46 M54 oil pump nut issue...that no one else could solve - all of those BMW tuners out there...

He set a really tough to beat NASA TT3 lap record. I don't think the car was even optimized the WT:HP ratio. I might possibly if I optimize the wt:hp with the wind is blowing the right direction with sticker hoosiers on...be in the same neighborhood as that lap record.

NASA also created a rule speciifically banning his car...how awesome is that!

[TDW_Nero]

APR GT250 67" Wing here. If i could do it over again I'd go with a 140cm GT4 wing.
You'll notice an improvement on putting down the power with any wing but the car will have a lot more mid-corner understeer if your damper setup is unchanged

[M3SQRD]

Rear wings are useful but need to be balanced by an appropriate sized front splitter. The BW F82 M4 GTmore R swan neck wing & R diffuser + GTmore F large splitter & dive planes & GTS/CS hood vent is an example of a balanced F-R aero setup. Ideally you want the aero COP to be close to the CG location of the car. R wing & diffuser is not useful without appropriate F aero.

[dogbone]

The challenge with aero is to produce as much downforce as possible with the least amount of drag. Aggressive wing angles create quite a lot of drag. Big wings, in theory, should be able to efficiently create downforce without having to dial in a huge angle of attack. A small wing by comparison would have to have a big angle of attack to match the downforce of a bigger wing. This big angle will create a lot of drag. I would also say that a small wing can't produce much downforce at low speeds, whereas a larger wing can still produce usable downforce at lower speeds.

A big wing will lead to stability in the rear end of the car, but without front aero, in high speed rounders/corners, the car will significantly understeer. I know because in 2015, I put a 67" APR wing on the rear of my E90 without any front aero. I did it knowing that I would get understeer, but I wanted to feel it for myself. I also got that wing knowing that at some point, I would get an APR front splitter. I didn't want to buy a small wing, and then another bigger wing later.

The understeer wasn't bad at moderate speeds like 65-80. But as the speeds increased it would get more and more. At Buttonwillow Raceway, the Riverside turn is a high speed rounder where the apex speed can be 95mph or more. In that turn, the steering wheel had almost no effect when you turned it because the understeer was so significant.

Once the APR splitter went on, the understeer was significantly reduced. The car was much better balanced. (My setup at the time was geared towards understeer.)

Now with Zebulon aero on both front and back, the car has more setup options. The car isn't setup with as much understeer like in the past. The tail can step out easily if desired.

Some other thoughts:

-Putting ANY kind of aero on the front that blocks air from going under the car can help with the understeer. So, you could at least start with the GT4 lip and see what that feels like.
-A chassis mounted splitter like the Zebulon that I have now is the ultimate setup in my opinion, but that doesn't mean a sheet of APR composite or alumalite isn't effective. It is. It's just that the Zebulon splitter can give you more downforce and the angle can be finely tuned to balance out the rear wing.
-Don't forget a big rear wing can be set at a very mild angle and it doesn't produce massive amounts of downforce. It will create drag (and slow you down on straights), but not necessarily tons of downforce if you keep the angle at a bare minimum.
-Of course, the shape of a wing is important. The owner of Zebulon has spent a large portion of his adult life in wind tunnels and staring at CFD analysis for big race teams. He has strong feelings about chord depth, wing shape, wing width, end plates, mounting position, etc. from all his time doing this kind of analysis and he puts that into his aero products. On my end, I can tell you that the Zebulon aero is bigger than the APR aero, but looking at AIM data analysis, the car is still faster on the straights......hmmmm

[BoilerUP]

dogbone,

Do you think a 61" GT250 would have paired better with your E90 than the 67" did, especially using an APR splitter?

What AOA did you run on the GT250?

thx

[dogbone]

Originally Posted by BoilerUP

dogbone,

Do you think a 61" GT250 would have paired better with your E90 than the 67" did, especially using an APR splitter?

What AOA did you run on the GT250?

thx

I was happy with how the car felt when I had the 67" wing and the APR composite sheet splitter. I thought they paired well with each other. Once I had the front aero on the car, I did have to increase the AOA of the wing, so it's not like I was running the APR wing at minimum angle with the splitter on the car. But I'm sure a 61" wing would be generally fine as well.

In 2017, there was a thread about APR wings. I posted several times in there and talked about my APR AOA along with other stuff. Instead of trying to quote that stuff here, I would highly recommend checking out that thread. I think the answers to your questions are in there. The thread is only 1 page.....although my posts are (of course) never short..... You can check it out here:

https://www.m3post.com/forums/showthread.php?t=1383497

[bigjae1976]

Originally Posted by dogbone

Once the APR splitter went on, the understeer was significantly reduced. The car was much better balanced. (My setup at the time was geared towards understeer.)

Something I found is that the material can make a big difference. I went from a plywood to a carbon splitter, both were the exact same size with the same mounting. The carbon splitter changed the balance from understeer to oversteer.