Aero setup for track days

[intercool]

I searched the forums and didn't find much about the effectiveness of different aero pieces (except for the wing).

What is the biggest bang for the buck and in what order to buy? I don't care about carbon fiber for looks as it gets expensive....
I'm thinking Rear wing, front diffuser, side canards, and maybe a real areo rear diffuser, but most of the posts don't show the effectiveness of the parts.

I mostly run at Road Atlanta with trips to Barber and VIR in the future.

[dogbone]

Originally Posted by intercool

I searched the forums and didn't find much about the effectiveness of different aero pieces (except for the wing).

What is the biggest bang for the buck and in what order to buy? I don't care about carbon fiber for looks as it gets expensive....
I'm thinking Rear wing, front diffuser, side canards, and maybe a real areo rear diffuser, but most of the posts don't show the effectiveness of the parts.

I mostly run at Road Atlanta with trips to Barber and VIR in the future.

I'm not sure what your expectations would be in terms of someone on a forum showing you the effectiveness of aero parts. Data from testing is a complete impossibility. Not even vendors test their own stuff in any meaningful way.

My journey with aero is fairly well documented in my build thread ( http://www.m3post.com/forums/showthread.php?t=1158445 ). The thread is pretty long now, but the Cliff Notes end result is that Aero is extremely effective but it needs to be balanced. I instantly picked up around 3 seconds at every single track I visited once full aero was on the car.

The three key pieces are:
-rear wing - plant the rear
-front lip - fill in the gaps for the splitter that will be below it and provide a place to screw in splitter
-front splitter - encourages air to go over the car instead of under, and creates an environment for front downforce

Everything else like canards, hood vents, wheel-well venting are all bits of favor that add very little. I like having that stuff on there too, but the main stuff is the three things listed above. You have to remember, these are very heavy cars. And since they are production street cars, things like the front bumper were not designed as a race part, so the air around the front bumper is pretty "dirty". So, the small changes like canards can mildly shape air flow, but on a 3500lbs street car, it ain't doing a lot.

A proper front splitter that sticks out 5" off the front of the car is very very difficult, if not impossible to drive on the street. So, your level of commitment to aero may be limited by certain practicalities if you daily drive the car.

I drove with only a rear wing (67" APR) and no front aero for awhile. The understeer in high speed rounders above 80mph was unbearable. Front aero made it all better.

If you look at the pix below, you'll see I have latches connecting the fender to the bumper. They were necessary because at high speeds, the bumper was pulling down and creating problems. Again, I talk about all this stuff in my thread. I know it's long, but there's stuff in there that I think could be useful to you.

Anyway, I've enjoyed experimenting with aero. I've tried to have fun with it----the one that really offends people is the Viper ACR-style holes we cut in the front fenders! I love them! People think I'm crazy. They keep asking me when i'm going to cover them with vents. I'm like, "Cover them? Why would I do that??!!! I love them!" haha! Finally, a couple months ago, a race tech walked up to my car and said....."ahhhh cool.....Viper style." FINALLY someone gets it!!! hahahaha

Here's what mine looks like these days:

[CorruptCommie]

Seconded that it works as a system.

dogbone - I would think that the fender vents would ease airfow over the fender, helping air from within the fender escape? Like a high pressure/low pressure type thing. I don't know though, not an aerospace engineer. Might also keep rocks launching into orbit

[dparm]

Originally Posted by CorruptCommie

Seconded that it works as a system.

dogbone - I would think that the fender vents would ease airfow over the fender, helping air from within the fender escape? Like a high pressure/low pressure type thing. I don't know though, not an aerospace engineer. Might also keep rocks launching into orbit

Correct, the openings in the fenders reduce turbulent air from fighting against the low-pressure zone under the car.

In other words, the wheel wells tend to fill with air that generates some lift and starts pulling the car off the road. The vents prevent that at the small expense of smooth airflow over the top of the fender.

And no, I have never seen any aftermarket aero parts share hard-data on whether or not they work. A good starting point would probably be to look at what BMW did on the E92 M3 GTR race cars and even the GTS: http://tech-racingcars.wikidot.com/bmw-e92-m3-gtr
https://www.supercars.net/blog/2008-...-race-version/
http://www.ultimatecarpage.com/spec/...92-M3-GTR.html

[dogbone]

Originally Posted by CorruptCommie

Seconded that it works as a system.

dogbone - I would think that the fender vents would ease airfow over the fender, helping air from within the fender escape? Like a high pressure/low pressure type thing. I don't know though, not an aerospace engineer. Might also keep rocks launching into orbit

hehe yes, people have tried to reason with me many times, just as you are. But I keep telling them "BECAUSE VIPER ACR!!!!!!" hahahahaha

C'mon---what's not to love?!!!

[ricardofors68]

I don't think you'll need aero work at the early stages of track days. I think the car is balanced enough to start with. I just have a front lip on mine for now. Brakes and suspension would do more at the beginning. But i do plan to add aero once I climb higher in the learning curve.

[intercool]

Thanks all! Yes, I always wondered about the side effects of adding pieces individually. It is good to know that it's not good to go with rear wing only bc it will cause front end problems. Will keep all this in mind during my journey!

[ilikebmxbikes]

what else is done to the car? cutting some weigh, upgrading brakes and getting better tires should be done first.

[spxxx]

Just an FYI for those of you mounting splitters, your bracket rods can mount to the bumper support not the plastic bumper cover if you want it to be more sturdy. I was able to cut small holes in my bumper that allowed the rods to mount to the chassis and reduced the amount of "pull" on the weak plastic bumper cover.

[intercool]

I have ST40 all around BBK, modest upgrade in suspension with 2.6 and 2.0 camber. but looking to get MCS next. 18 square with nitto 01's 275/35 BUT I'm thinking about going with RE71's.

Like everything else, this is SOOO ADDICTIVE and I'm looking ahead to see what to budget for... :-)

I'm looking for things to inspire confidence as I'm still new to DE events... I still lift right before turn 10 at Road Atlanta...

I actually picked this up from the forum: http://www.m3post.com/forums/showthread.php?t=1409130
I added carbon fiber drive shaft and a few other bits.

[SYT_Shadow]

my goodness dogbone your car looks so awesome!

And yes, because ACR. I've seen them in person and shudder

[dogbone]

Originally Posted by SYT_Shadow

my goodness dogbone your car looks so awesome!

And yes, because ACR. I've seen them in person and shudder

thanks! she's a bit crazy now, but she sure is fun to drive!

I was bummed that I waited too late to sign up for Global Time Attack at Buttonwillow....sold out. However, there is Bimmer Challenge at Big Willow....hmmmmm

[CorruptCommie]

Originally Posted by intercool

I have ST40 all around BBK, modest upgrade in suspension with 2.6 and 2.0 camber. but looking to get MCS next. 18 square with nitto 01's 275/35 BUT I'm thinking about going with RE71's.

Like everything else, this is SOOO ADDICTIVE and I'm looking ahead to see what to budget for... :-)

I'm looking for things to inspire confidence as I'm still new to DE events... I still lift right before turn 10 at Road Atlanta...

I actually picked this up from the forum: http://www.m3post.com/forums/showthread.php?t=1409130
I added carbon fiber drive shaft and a few other bits.

As well you should! Probably flying into T10 at 140+
I kid, you probably meant T12. That track is awesome.

[M3 Number 86]

I added this chassis mounted splitter bc with only a wing ad gt4 lip I had high speed understeer. Mine is a 61" at zero angle and it was still too much understeer for me.

Daily driven but only to daycare and work. No guessing about steep driveways lol. Wife's car does weekend duties now ha

[ricardofors68]

That splitter goes all the way back to the metal plate under the engine?

[nicksm3]

Originally Posted by dogbone

I'm not sure what your expectations would be in terms of someone on a forum showing you the effectiveness of aero parts. Data from testing is a complete impossibility. Not even vendors test their own stuff in any meaningful way.

My journey with aero is fairly well documented in my build thread ( http://www.m3post.com/forums/showthread.php?t=1158445 ). The thread is pretty long now, but the Cliff Notes end result is that Aero is extremely effective but it needs to be balanced. I instantly picked up around 3 seconds at every single track I visited once full aero was on the car.

The three key pieces are:
-rear wing - plant the rear
-front lip - fill in the gaps for the splitter that will be below it and provide a place to screw in splitter
-front splitter - encourages air to go over the car instead of under, and creates an environment for front downforce

Everything else like canards, hood vents, wheel-well venting are all bits of favor that add very little. I like having that stuff on there too, but the main stuff is the three things listed above. You have to remember, these are very heavy cars. And since they are production street cars, things like the front bumper were not designed as a race part, so the air around the front bumper is pretty "dirty". So, the small changes like canards can mildly shape air flow, but on a 3500lbs street car, it ain't doing a lot.

A proper front splitter that sticks out 5" off the front of the car is very very difficult, if not impossible to drive on the street. So, your level of commitment to aero may be limited by certain practicalities if you daily drive the car.

I drove with only a rear wing (67" APR) and no front aero for awhile. The understeer in high speed rounders above 80mph was unbearable. Front aero made it all better.

If you look at the pix below, you'll see I have latches connecting the fender to the bumper. They were necessary because at high speeds, the bumper was pulling down and creating problems. Again, I talk about all this stuff in my thread. I know it's long, but there's stuff in there that I think could be useful to you.

Anyway, I've enjoyed experimenting with aero. I've tried to have fun with it----the one that really offends people is the Viper ACR-style holes we cut in the front fenders! I love them! People think I'm crazy. They keep asking me when i'm going to cover them with vents. I'm like, "Cover them? Why would I do that??!!! I love them!" haha! Finally, a couple months ago, a race tech walked up to my car and said....."ahhhh cool.....Viper style." FINALLY someone gets it!!! hahahaha

Here's what mine looks like these days:

I love it and it makes sense! And wow!!! 305’s upfront? How in the world did you manage that? Spacer obviously but did you change the spring perch?
285’s are great but I can only imagine the sheer grip of 305’s !

[warp10]

Here is my aero set up for Road Atlanta

APR 250 wing
Gt4 lip
Lower chassis mounted alumalite splitter
Bimmerworld dive planes
Track spec vented hood
GT3RS inspired fender vents
And rear diffuser

[dogbone]

Originally Posted by nicksm3

I love it and it makes sense! And wow!!! 305’s upfront? How in the world did you manage that? Spacer obviously but did you change the spring perch?
285’s are great but I can only imagine the sheer grip of 305’s !

Hehe I’ve talked about this many times now.

305 fits with JRZ damper, no helper spring, 5” main spring, no fender liners.

On Apex ARC-8 10.5” ET 27, I used a 3mm spacer.

On Titan 7 10.5” ET 25, a spacer is not required for damper clearance but I still use the 3mm spacer to clear the VF supercharger intake.

The 305/645/18 does rub mildly in various places around the wheel well when turning the steering wheel, but it has not been a problem. And yes, the grip is amazing.

[nicksm3]

Originally Posted by dogbone

Hehe IÂ’ve talked about this many times now.

305 fits with JRZ damper, no helper spring, 5” main spring, no fender liners.

On Apex ARC-8 10.5” ET 27, I used a 3mm spacer.

On Titan 7 10.5” ET 25, a spacer is not required for damper clearance but I still use the 3mm spacer to clear the VF supercharger intake.

The 305/645/18 does rub mildly in various places around the wheel well when turning the steering wheel, but it has not been a problem. And yes, the grip is amazing.

Appologies as I am hardly on here, and when I do it’s for informative insight ...which mainly you provide. So thank you!

I’m running MCS 2 way, I do have the new APEX SM-10 - 10.5 square. My 285 BFG R1’s rub the collar if I don’t run a 10mm spacer...this will be tough but...where there’s a will there is a way

[XCUSE_M3]

Originally Posted by nicksm3

Appologies as I am hardly on here, and when I do it's for informative insight ...which mainly you provide. So thank you!

I'm running MCS 2 way, I do have the new APEX SM-10 - 10.5 square. My 285 BFG R1's rub the collar if I don't run a 10mm spacer...this will be tough but...where there's a will there is a way

I ran the 305 last weekend with slight rubbing as dogbone stated. I also have the MCs 2wr just put a 5in spring and no helpers in and you will be good to go besides getting rid of those fender liners.