APR GTC200 Setting
 

Anyone running the GTC-200 wing? Installed mine and have it at the lowest setting, the base plate is obviously tilted (due to trunk design) and am wondering if the wing angle needs to be adjusted and if so how much. On my previous cars, I'd get baseline from the known race company (Bimmerworld) taking the guesswork out but would appreciate if folks running it can chime in on the height they have tested and their findings.

TIA

Lutfy

I'm no aero pro and have no first-hand experience with it. That said, you probably want to share more information like other aero modifications, suspension setup, tires, etc. I see from your signature you're competing in time trials, so that is helpful.

550/550lbs Motion Control Suspension (MCS) double adjustables, TRD swaybars, ride will be set to 13 -13.25 inches hub to fender f/r, 255 R888 with 17*9 wheels. APR non adjustable front splitter. Weight 2700lbs without driver.

Cheers,

Lutfy

Very similar setup to mine, except my suspension is slightly softer (around 340/450 F/R) and I have a bit more rake (about 1/2 in), same size wheels with 245 RS4 tires and same front splitter and wing. My car is NA and on stock swaybars.

I have played with 3 settings on the wing. Full angle, minimum angle, and middle. I found my car understeered like a pig at full angle, understeered like a smaller pig at medium and had a small understeer at minimum angle. I added hood vents to the car and the aero balance changed, now its slighly loose at minimum angle (very very small, its almost all neutral) with the dampers being set softer in front than rear, and its about neutral with a hint of understeer if dampers set harder on front.

Regarding speed traps (from videos and just eyeballing the speedo before braking on straights), my top speed drops by around 5-8mph on a 100+mph straight from maximum angle, to minimum angle.

Regarding lap times, Im around 1sec per minute faster with the wing at minimum angle vs maximum angle.

Middle angle was like maximum, but less. Meaning less drop in lap times, less drop in speed, less understeer, but still worse than at minimum angle.

Hope this helps.

Awesome info! I intend to realign to -2.8/9 front and likely static -2.2 (stock arms).... My fear when looking at the wing was that the angle looked a bit reversed (from the middle) giving me fear of having lift (reverse tilt) but your feedback allows me to go and test it out. If you can share any pics, that would be great!! So so many variables (converted from TTE to TTD overnight) I have one test weekend before timed event so want to make sure I have all the notes/data/documentation prior.

Cheers,

Lutfy

I get what you mean, indeed the wing looks like it has negative angle (and it does!) but it is still generating downforce at negative angle, and according to APR themselfs, the wing is most efficient at -2 angle of attack (which is around what the minimum angle is). I forgot to mention camber, I run a retarded amount of camber, -3.8 in the front, -3.2 in the rear. I started increasing it from -3 front and -2 back until my current setup, every time I added more camber, I went around the track faster... At -3.8 I think the front still needs a bit more, at -3.2 I think the rear needs a bit less, Im going to try -4.0 front and -3.0 rear next, see how that works out. I have -0.1 toe (toe-out) front, and 0 toe rear.

Amazing info thanks mate!! The wing angle is one less worry. Got all the baseline I need to hit the ground running!!

Lutfy


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Bringing up an old thread. Have you measured the AOA at full min to see its actually -2? I ended up getting a shorter height link from APR to see if I can actually go lower. With 3d wings you still have df and drag at - AOA so I may go down to as much as -4 if possible.

Am losing a LOT of speeds in the straight and seriously contemplating going with the 2d GT250 wing.

Lutfy

I have the same problem as you with speed Lutfy. I put the wing at -2 and there certainly is enough room to go down more. I will be at a high speed track this next tuesday so I will try 0, -2, and however much lower I can go and collect some data. You can totally tell the différence between say +5 and -2, the rear is completely different, specially during trail braking. I have gotten better at that so I think I will be faster with a lower drag, lower DF setup. I will try to come back here and post some data if I remember. Maybe quote me or msg me if not, I always check alerts on the forum.

Thank God I am not the only one :) I got shorter height adjusters from APR. They are to be mailed out today. I will measure my current setup (whatever the angle is now at lowest setting) and set the same with the shorter link. I can then go down each degree per session until I find a resolution. I 'think' I can go faster as I have way much DF at the back, car is touch understeery and the drag on the straight hurts speed.

Before moving on to a GT250 I want to exhaust all options first.

Lutfy

PS: @Icecreamtruk perhaps you can also get the shorter links overnighted to you and do the same prior to your tuesday run?

My balanced got quite a bit better after I installed canards. So if you havent done that, its a cheap and effective way of getting more front downforce, but it will cost you extra drag, so to keep that in mind.

Unfortunately canard and diffuser or even vortex gen are illegal in class so I will just have to toodle with the wing. Per your earlier post I did the hood vents and it made a pretty noticeable difference (less high speed understeer).

Lutfy

What do you expect to be different with the 250 wing?

[QUOTE=Sleepless;3128564]What do you expect to be different with the 250 wing?[/QUOTE

Less drag especially at higher speeds. More efficient wing.

Ordered a set of shorter rods and will go down to as low as -4 degree to balance and also gain some mph at VIR.

Lutfy