All Things Mk5 > Performance Modifications

Improving aerodynamics with aftermarket parts

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rex:
If there is stock lift and wing dowforce, in order to see the benefits you should add the 2 values (or improvement = WingDonwforce - ( - Stock lift)).

fuscobal:
Lift and downforce have opposite directions so you simply add them (one is vertical up and has -, the other is vertical down and has +). The bolded values are the final result wich is a small amount of downforce, knowing the wing bring a little more downforce @ a certain speed thn the lift of the OEM car @ same speed !

the bruce:
First: Think we should a link here to your pictures:

http://www.mk5golfgti.co.uk/forum/index.php/topic,12484.msg698714/topicseen.html#msg698714


To me it's better to read this way:


speed  >>> stock lift >>> wing DF >>> Total 1 >>> wing + gurney DF >>> Total 2
in km/h . . . . . . . . . . . . . . . . . . . . . (wing DF - stock lift) . . . . . . . . . . .  (wing + gurney DF - stock lift)

   80 >>>> +5.92 kg >>>>> -7.50 kg >>> -1.58 kg >>>>> -9.38 kg >>>>> -3.46 kg

 100 >>>> +9.25 kg >>>> -11.72 kg >>> -2.47 kg >>>>> -14.65 kg >>>>> -5.40 kg

 120 >>> +13.32 kg >>>> -16.88 kg >>> -3.56 kg >>>>> -21.09 kg >>>>> -7.77 kg

 140 >>> +18.13 kg >>>> -22.97 kg >>> -4.84 kg >>>>> -28.71 kg >>>>> -10.58 kg

 160 >>> +23.68 kg >>>> -30.00 kg >>> -6.32 kg >>>>> -37.50 kg >>>>> -13.82kg

 180 >>> +29.97 kg >>>> -37.97 kg >>> -7.99 kg >>>>> -47.46 kg >>>>> -17.49 kg

 200 >>> +37.00 kg >>>> -46.88 kg >>> -9.88 kg >>>>> -58.59 kg >>>>> -21.59 kg


Added a '+' to the lift values and a '-' to the downforce ( negative lift) values.



Most interesting - What to conclude?

I'd guess depending on track most important turns are between 80 and 140 km/h. I'd say:

1.
At 80 km/h it may be of lesser significience if you have 6 kg of lift on rear or 3.5 kg DF.

2.
At 140 km/h it definitely matters if you have 18 kg lift or you have a downforce of 10.5 kg
instead, even more if you turn in and have still your foot on the brakes.

3.
If you apply the brakes at the end of start/finish rear grip will be vastly improved.
37 kg lift compared to 22 kg downforce - it's a difference of almost 60 kg at a moment when
dynamic corner weights are often below 100 kg !!! Rear wheels now have a chance to take
part of deceleration.

rex:
Oh, fuscobal, now I understand... We were both right!
You were calculating the DF you have at various speeds and I was looking to see the gains over the stock setup...

fuscobal:
Rex, gain over stock is exactly the columns wing df or wing + gurney df :)

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