Yargk

Yep.

ScottL

Some interesting data from Reverie
http://www.reverie.ltd.uk/latest_new...Test%20Results

I understand this is achieved via a new font lip spoiler (pic below) and a rear diffuser. (no picture on the web site)



Interesting to note that a higher ride height generates more downforce.

ScottL

On a related topic I was driving a KTM X-Bow on track a few weeks ago. It has around 50kg's on downforce at 60mph and 200kg's at 125mph. The cornering speeds are immense. Bear in mind it's road legal and the ride height is greater than a 997GT3.




I hope Porsche put more effort into the aero on future cars. I think there is a lot to gain without too much compromise.

Yargk

That is interesting data. Combined with an RS or Cup wing would be even better. Interesting how on the Cup, there is front lift. I wonder if this is from so much rear downforce that you get a seesaw effect.

If you want the car to remain neutral you should have downforce proportional to the weight of the car on the front and rear. So if a GT3 has 39 pounds of front downforce it should have 61 pounds of rear downforce. However, you really don't want it to remain neutral, you want to have the rear stick better for some confidence in the sweepers. That way things will be planted (push a little) at high speed and you can throw it around a little more at low speed.

So I wonder what's optimal on a 911. 3:7 front:rear 1:4 front rear? I wouldn't use the standard cup car as the ideal since it only races against other cup cars so not everything is optimized on it. What's the downforce ratio for the grand am cup cars with the high downforce front end. Or the Cup S (racing in GT3) car, or the RSR (in GT2)?

C.J. Ichiban

keith, now you're really getting it! just keep in mind the spring/shock settings as well- cup cars have 600+ lb springs in the front so the car will compress and rebound a lot less than the standard road car.

RSRs can run a lot more downforce because they're suspended super tight.

aero also has to be optimized with gear ratios when considered per track, well at least it does in F1.

Yargk

Also, I think two things are going on. First, as you have said, if you press down more in the rear than the front then you'll change your ride height rake. (really you'd have to push more than the ratio of the spring rates in the rear to the front because if you have 1000 pounds of df on the rear and 1000 pound springs in the rear and 600df/ 600 pound springs in the front, then your rake will still be level).

However, if your rear wing is directly above your rear tire, you'll still get a rake change and this will change your front downforce because the car is tilted up, but you don't get front lift JUST because of the extra rear downforce (no seesaw force). I think you get the seesaw force if the rear wing is behind the rear wheels because then you have a lever arm to seesaw the front up (see the side view of your RS and the rear wing relative to the rear wheel).

So extra front lift is indirectly caused by unbalanced rear downforce due to air getting under the car and this is more pronounced with softer springs, however you probably a larger effect on lift on the front is just because the rear wing is behind the rear wheels. I'd venture to guess that even if you actually soften the Cup springs, but move the rear wing to sit directly over the rear wheels, that the front lift would be reduced.

997gt3north

- great post
- what i find interesting and did not really expect was that there wasn't really any aero benefit with the much lower drop height (114/140 vs the slight change from stock 126/152 )
- i have been thinking about this part from gmg for next season so it is nice to see the data (put it on for trackdays, take it off after)

http://www.gmgracing.com/images/splitter3.jpg