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2016 Wrx Sti
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Discussion Starter · #1 ·
Hello everyone!

I just recently installed APR GTC-300 67” wing on my 16 sti.
There are several holes for the wing to sit at different angles for aerodynamics, I was wondering which is preferred. I have it at the lowest one which wing sits tilted down forward.

Thank you in advance.
here is also of my vehicle with the wing.
Note* this car isn’t a daily.
Car Wheel Sky Tire Vehicle
 

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Honestly it depends what you’re intentions are. If you are just an Instagram clout chaser then don’t think twice and just run the most aggressive AoA there is lol.

for the real world and people who track their cars, you can find all the CFD information on APR’s website. They also provide information on how many lbs of downforce are certain speeds with certain degrees of angle (angle of attack or AoA).

out of curiosity do you run aero wise For the front? You want to keep a balance so if you’re now running more downforce in the rear, I assume you have a splitter setup or some canards up front

I run a 70” carbon element at the minimum AoA for my setup which works out to be about 5°, and it’s way too much. Have ordered a new setup which will balance better, but it does look sick though
 

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2016 Wrx Sti
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Discussion Starter · #3 ·
Honestly it depends what you’re intentions are. If you are just an Instagram clout chaser then don’t think twice and just run the most aggressive AoA there is lol.

for the real world and people who track their cars, you can find all the CFD information on APR’s website. They also provide information on how many lbs of downforce are certain speeds with certain degrees of angle (angle of attack or AoA).

out of curiosity do you run aero wise For the front? You want to keep a balance so if you’re now running more downforce in the rear, I assume you have a splitter setup or some canards up front

I run a 70” carbon element at the minimum AoA for my setup which works out to be about 5°, and it’s way too much. Have ordered a new setup which will balance better, but it does look sick though
Thanks for the feedback,
I still want a good AoA performance for the car. So the angle of the wing do bother me cause I want good performance.
Currently don’t have any social media so that’s a no to clout chasing lol. But I was planned on just using this car for shows even though that’s clout. Lol but anyways also fixing up the engine as well. Currently on flex fuel 350whp / 398 torque. Awaiting to go more with a built closed deck.
Just fixing this car up slowly while it sits on my backyard to my likings.
Plan on getting a varis or charge speed front end. So might end up getting aero stuff in front as well.
 

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should be able to look up on APR's website what the benefit would be for AoA in terms of downforce vs some sort of drag ratio, as 320 mentioned. more angle is NOT always better, and can definitely hurt performance. i'd lookup kyle engineer on youtube, he explains aero super well.
 

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2016 Wrx Sti
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Discussion Starter · #5 ·
should be able to look up on APR's website what the benefit would be for AoA in terms of downforce vs some sort of drag ratio, as 320 mentioned. more angle is NOT always better, and can definitely hurt performance. i'd lookup kyle engineer on youtube, he explains aero super well.
thanks I shall check him out and yeah I want what’s best for performance.
 

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Out of curiosity i tried to look it up yesterday. Now I just want to state that the fact a 2015+ STi can be optioned from the dealer WITHOUT the rear wing, then it’s clearly not necessary for the vehicle. If it truly made a difference for vehicle stability then it wouldn’t be an option to remove.

there are a few threads on the Internet of people that have done their own modeling/CFD on the oem wing and it shows to create about 60lbs of downforce at 100mph.

so looking at the tables below from the APR website, your GTC-300 looks to be making about 237lbs at the same 100mph with 0° AoA, or about 4x the amount of downforce at the same speed.

considering your photo looks like you’ve almost maxed out the AoA, at 100mph you’re making over 300lbs at 100mph or 5x OEM…

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So I’d study and learn as much as you can about aero, great suggestion above to check out Kyle engineerings YouTube channel. You need to think of your STi as an entire package and where the effective centre of gravity is. If you plan to add rear aero, you need to consider front aero ad well.

also for a daily driver it makes a big difference on fuel economy. On my focus RS no aero I average 10.2L/100km fuel economy. With the aero it’s about 12.3L/100km.

you can also use your cobb accessport to datalog changes too. Cruising At 130kmh in my RS without aero it takes 30% throttle input, whereas with aero its 38% input, same stretch of hwy and same speed etc.

This is all anecdotal, I’m no engineer. But for the weekend mechanic it’s a fun little rabbit hole to fall into.

Wheel Tire Car Vehicle Window


edit: check out this guys YouTube channel. Search for the videos that he’s done in the wind tunnels, also very interesting. Especially the ones where he does the yarn tuft tests

 

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Discussion Starter · #7 ·
Out of curiosity i tried to look it up yesterday. Now I just want to state that the fact a 2015+ STi can be optioned from the dealer WITHOUT the rear wing, then it’s clearly not necessary for the vehicle. If it truly made a difference for vehicle stability then it wouldn’t be an option to remove.

there are a few threads on the Internet of people that have done their own modeling/CFD on the oem wing and it shows to create about 60lbs of downforce at 100mph.

so looking at the tables below from the APR website, your GTC-300 looks to be making about 237lbs at the same 100mph with 0° AoA, or about 4x the amount of downforce at the same speed.

considering your photo looks like you’ve almost maxed out the AoA, at 100mph you’re making over 300lbs at 100mph or 5x OEM…

View attachment 66859

So I’d study and learn as much as you can about aero, great suggestion above to check out Kyle engineerings YouTube channel. You need to think of your STi as an entire package and where the effective centre of gravity is. If you plan to add rear aero, you need to consider front aero ad well.

also for a daily driver it makes a big difference on fuel economy. On my focus RS no aero I average 10.2L/100km fuel economy. With the aero it’s about 12.3L/100km.

you can also use your cobb accessport to datalog changes too. Cruising At 130kmh in my RS without aero it takes 30% throttle input, whereas with aero its 38% input, same stretch of hwy and same speed etc.

This is all anecdotal, I’m no engineer. But for the weekend mechanic it’s a fun little rabbit hole to fall into.

View attachment 66860

edit: check out this guys YouTube channel. Search for the videos that he’s done in the wind tunnels, also very interesting. Especially the ones where he does the yarn tuft tests

Damn I appreciate this! That’s very helpful! And your car looks amazing.

I will be making the adjustment to the wing angle for better AoA preferably 0AoA.

and yeah I shall get for the front. My driveways eats up anything in the front bumper since it’s steep.

but overall, I appreciate this!
 

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It's a balance between front and rear down force for any given suspension setup. The best way to find out how the attack angle need to be set... Take it on track. If you're new, you won't find that point for probably 20 track days or so, and you already have plenty of power for track (too much of n00b).

My aero guy (www.zebulonmsc.com) builds my wing and splitter setup to be balanced and cautions me to never run one without the other. I did find in my setup, I had to add a few degrees of rear attack angle (my splitter is also adjustable) in the 90+ mph turns. Overall, it still has very little attack angle.

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I have an additional element and larger end plates coming for AutoX speeds.
 

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I will parrot what yamahaSHO already said. My GV has no front aero and I have my GTC300 set to the LOWEST downforce setting. On the track, the lack of front DF is very apparent....without a splitter, you shouldn't be running any angle.
 

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I ran a GTC-200 on my S2000 years back and IIRC I just left it at 0 AoA and found it to be adequate. I believe quite a few others did at the time as well that were in the TTC realm. That was also with a front hood vent that was placed using differential pressure readings.

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best way to find out how the attack angle need to be set... Take it on track. If you're new, you won't find that point for probably 20 track days or so
this! And also be willing to accept that the car might be faster without the wing. In between sessions I’ve removed the wing on my car. Felt no loss of traction in the rear and it holds its higher speed better. But I like the way it looks with the wing and I’m just out for fun. I’m willing to give up a second or two a lap. My point is, even if it’s not totally functional that’s okay as long as it’s not totally detrimental.

the biggest difference handling wise was adding a lower airdam on the splitter. Added a fair amount of grip to the front at 100+kmh

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