[72dan]

I know this has been discussed but I think there is a lot of mis-information. The common consensus here and at APR is that the GT-250 wing works better on an E92 M3.
The assumption is that we are all okay with a 67" wide wing that sits 18" above the trunk lid such that people bang their head on the edge of the wing if you are parked in a public parking lot and someone walks down the aisle between you and the car parked next to you.

The reality is many of us want a wing that is shorter, 61" or even less, maybe even 48" wide and only 6"-12" off the trunk lid because we street drive the car. 48" is about the width of the trunk.

So the nutshell opinion is that the GTC-300 is more "draggy" and that the E92 doesn't have enough horsepower for a wing that "draggy". But the reality is the GTC is a much more efficient wing when you compare the L/D ratio, that is lift vs drag, and we are really looking at negative lift, an airplane wing upside down.

The GTC-300 is already making 151 lbs of downforce at 0 degree angle at 80 mph, whereas the GT-250 is making a fraction of that, 43.8 lbs of downforce. In fact for the GT-250 to make as much downforce as the GTC-300 makes at 0 degrees, we have to run the GT-250 around 13 degrees interpolating stated downforce at 10 and 16 degrees.

Most have said they run their GT-250 at 0-5 degrees, so the reality is that if we hang a 67" GTC-300 18" in the air we just can't get enough front downforce to balance it out. So why not run a GTC-300 that is only 48" wide?

That statement that the GTC-300 is more "draggy" is incorrect. The numbers for it were stated in Newtons, so I put all the data in excel, converted it to lbs and also calculated L/D ratios on it, as APR publishes the numbers in lbs for the GT-250

So, running the GT-250 at 10 degrees would give a L/D ratio of 7.52 , at 16 degrees a L/D ratio of 5.28. Remember higher is better, we want to make the most downforce with the least amount of drag.

So, then lets look at the data for the GTC-300. At 0 degrees and 80 mph the L/D ratio is 8.83, it is a far more efficient wing than the GT-250.

So that is the race car engineering theory, the GTC-300 may actually be better as a more narrow wing lower mounted than the GT-250 full race wing based on much more efficient L/D ratios.
Have any of you tried a smaller GTC-300 wing mounted closer to the trunk surface?