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      03-27-2017, 06:59 PM   #1
SnapCoupe
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To those with aftermarket aero on their Coupes

With track and autocross season just around the corner, I have begun laying out a list of a few mods that I would like to get done before my first event. Near the top of my list is some aero for the car, particularly the APR front lip and the APR GT wing or the VARIS/Voltex option if I can come across a decent deal. My question to those with these installed on their cars; is how noticeable is the stability and down force difference from stock? Personally I have noticed the M coupe to have a lofty front end at speed, so I could imagine a front splitter might help with that.

I know big aero on a car that is not strictly for the track is a controversial subject around these parts, so please refrain from "BIG WANGS R DUM".

So, thoughts, experiences, opinions?
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      03-27-2017, 10:23 PM   #2
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I love the look of a big wing on the back of a coupe, and you won't catch me scoffing. Aero also means that the car gets classed differently and may be detrimental in PAX modifier.

That said, there are much more valuable items to purchase for Autocross (Most of my racing experience). I think that wheels, tires and allowable brake modifications should take precedence. Reducing the unsprung weight and allowing really grippy tires to stay on the pavement are a big bang for the buck.

In most Autocross events, braking will be the biggest reduction in time. Usually elements are close enough that it almost limits the effect power has, but being able to brake harder and set up for the corners allow you to carry that speed deeper into the element.

Getting a good alignment will also likely give more benefit to the handling of the car than aero.

Of course in higher speed courses and on the full track, aero will play a bigger part.

Here's a discussion going about BSP classing of the Z4 coupe and I'll be adding to it as I experiment this season.

http://www.zpost.com/forums/showthread.php?t=1367315
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      03-28-2017, 05:36 AM   #3
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Love my APR Aero.
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      03-28-2017, 11:46 AM   #4
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Quote:
Originally Posted by SnapCoupe View Post
With track and autocross season just around the corner, I have begun laying out a list of a few mods that I would like to get done before my first event. Near the top of my list is some aero for the car, particularly the APR front lip and the APR GT wing or the VARIS/Voltex option if I can come across a decent deal. My question to those with these installed on their cars; is how noticeable is the stability and down force difference from stock? Personally I have noticed the M coupe to have a lofty front end at speed, so I could imagine a front splitter might help with that.

I know big aero on a car that is not strictly for the track is a controversial subject around these parts, so please refrain from "BIG WANGS R DUM".

So, thoughts, experiences, opinions?
I've done a ton of work on aero.
For the rear wing I'm now using the APR GTC200 and love it.

Everything else is custom; started with the APR splitter but I needed more on track.

http://www.zpost.com/forums/showthread.php?t=1270556
http://www.zpost.com/forums/showthread.php?t=1359348

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      03-28-2017, 04:00 PM   #5
SnapCoupe
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Quote:
Originally Posted by Jackal View Post
I love the look of a big wing on the back of a coupe, and you won't catch me scoffing. Aero also means that the car gets classed differently and may be detrimental in PAX modifier.

That said, there are much more valuable items to purchase for Autocross (Most of my racing experience). I think that wheels, tires and allowable brake modifications should take precedence. Reducing the unsprung weight and allowing really grippy tires to stay on the pavement are a big bang for the buck.

In most Autocross events, braking will be the biggest reduction in time. Usually elements are close enough that it almost limits the effect power has, but being able to brake harder and set up for the corners allow you to carry that speed deeper into the element.

Getting a good alignment will also likely give more benefit to the handling of the car than aero.

Of course in higher speed courses and on the full track, aero will play a bigger part.

Here's a discussion going about BSP classing of the Z4 coupe and I'll be adding to it as I experiment this season.

http://www.zpost.com/forums/showthread.php?t=1367315
Like I said, aero is a small item on a large list. I already have suspension, wheels/tires, motor and trans mounts, and a few other things on order. I plan to be "ballin' out with the car over the next 2 summers. I will only be doing a few autocross events as I much prefer full tracks.
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      03-28-2017, 05:07 PM   #6
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Quote:
Originally Posted by inTgr8r View Post
I've done a ton of work on aero.
For the rear wing I'm now using the APR GTC200 and love it.

Everything else is custom; started with the APR splitter but I needed more on track.

http://www.zpost.com/forums/showthread.php?t=1270556
http://www.zpost.com/forums/showthread.php?t=1359348

How did you like the APR splitter when you had it on? What were your complaints with it that pushed you to work with custom aero?
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      03-28-2017, 05:54 PM   #7
inTgr8r
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Quote:
Originally Posted by SnapCoupe View Post
How did you like the APR splitter when you had it on? What were your complaints with it that pushed you to work with custom aero?
One of the main problems with our car is the way the bumper undercuts the front tire.
The exposed rotating tire is a big air flow disturbance.

To help with this BMW added the front air ducts which pressurizes the wheel well.
This helps to push the air past the wheels.

The problem with this is it adds a lot of lift in the wheel wells.

With the custom pieces, the air flows naturally past the wheel arch
and allows the front air ducts to be closed off.
(I'm using them to run brake cooling ducts)

Also, the original APR wasn't big enough to balance the car with a large wing.
(I think they do larger ones now on request)

They other reason is I got tired of the APR look.
JMO, but the plastic edging looks very low end to me.
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      03-28-2017, 06:24 PM   #8
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Quote:
Originally Posted by inTgr8r View Post
One of the main problems with our car is the way the bumper undercuts the front tire.
The exposed rotating tire is a big air flow disturbance.

To help with this BMW added the front air ducts which pressurizes the wheel well.
This helps to push the air past the wheels.

The problem with this is it adds a lot of lift in the wheel wells.

With the custom pieces, the air flows naturally past the wheel arch
and allows the front air ducts to be closed off.
(I'm using them to run brake cooling ducts)

Also, the original APR wasn't big enough to balance the car with a large wing.
(I think they do larger ones now on request)

They other reason is I got tired of the APR look.
JMO, but the plastic edging looks very low end to me.
I came here to be schooled on aero, and I got exactly that. Thanks for the info. Do you feel as if a GT wing will completely mess with the cars handling and balance without large front end aero? Will a mild amount of rake help with this as well?
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      03-28-2017, 07:15 PM   #9
inTgr8r
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Quote:
Originally Posted by SnapCoupe View Post
I came here to be schooled on aero, and I got exactly that. Thanks for the info. Do you feel as if a GT wing will completely mess with the cars handling and balance without large front end aero? Will a mild amount of rake help with this as well?
No problem.

Its all a balancing act with many other variables.
Rake can definitely impact setup, but its more of a finishing element than primary design (IMO, others may differ).
There have been a few interesting discussions in the past if you want to start digging.
re adding the GT wing, you definitely need to balance what you do out back with the front.
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