[Otto]

billc you have me scratching my head now

what is the difference between less lift and more down force?

this weekend was the first time i have even driven a cayman at speed

the difference from my 06 boxster s was amazing on many levels

however, i could feel the rear end lift and the front end dance at speeds approaching 130mph at various points on track - so much so that i backed off a bit several times

[Dandelion]

Less lift = there is still less overall weight on the wheels at speed.

Downforce = more overall weight on the wheels at speed.

ed

[trytryagain]

It was pretty windy around here. Could you have been feeling wind gusts, especially on the back stretch, which is very exposed?

[vranko]

^ if you really want to feel those gusts (which I thought were fairly minor last weekend) drive my Golf! It's a box with wheels.

[Otto]

yes, that too

[ausgeflippt951]

Originally Posted by OttoBurgess

billc you have me scratching my head now

what is the difference between less lift and more down force?

this weekend was the first time i have even driven a cayman at speed

the difference from my 06 boxster s was amazing on many levels

however, i could feel the rear end lift and the front end dance at speeds approaching 130mph at various points on track - so much so that i backed off a bit several times

Downforce = "negative lift".

Just at a high level: So, every production/sports car produces lift at speed. i.e., they actually get lighter the faster they go (usually by many hundreds of pounds at 120mph). Only the most sophisticated, aero-focused race cars are actually producing true downforce at speed (i.e., making the car get heavier at speed).


The "wing" on the Cayman R allows better flow than the little speed-activated spoiler on the normal models. But at best, it's still not really impacting downforce. Think of it more as a stabilizer -- it will help make your car feel more stable thanks to more efficient flow, but because its impact on the car is still extremely small, it's not worth saying the wing is capable of any appreciable amount of downforce.



It does look good though!

[RV4Flyer]

http://en.wikipedia.org/wiki/Aerodynamic_lift It doesn't take much of an airfoil to create a huge amount of lift. Look at the small wings on some of the commercial jets and how much weight they can lift. By having a wing on the rear it creates downforce through aerodynamic lift but inverted. To say you can get more downforce with less lift is not a valid statement. It probably also aids, and this is only a guess, to reduce induced drag from the large rear end of the car, and yes the rear end does create drag.

Like Otto, I found at about 120mph in my Cayman S that the front end began to lift. At 140 I felt it was time to pull back on the stick and go airborne but I'll save that for the airplane. I found some front splitters on Ebay in the $300-$400 range. I need to get these on my car as well.

My buddy Scott from PA, also at VIR, added a Cayman R wing to his 09 S. I'll ask him what he did to deactivate the automatic wing and pass it along.

When the discussion of lift comes up it should also include a discussion of angle of attack and drag. So here is something for you to ponder regarding drag. Which has more drag, a round bar or a rectangular bar......and why?

[Otto]

this is from the cayman aerokit ii install pdf....

7 Concluding work

7.1 Code “Fixed spoiler” using the PIWIS
Tester 9718 .

7.1.1 Select “Rear” control unit group and press •>>“.

7.1.2 Select “Coding” menu item and press •>>“.

7.1.3 Select “Fixed spoiler – not installed” in the menu and change the coding by
pressing •>>“.

7.1.4 Switch from “not installed” to “installed” under “Change coding”.

7.1.5 Write coding with •F8“.

7.2 Read out the fault memory of all control units, correct any existing faults, and then erase the
fault memory.

Working Time: 66 58 31 03 –Installing Aerofit for Cayman, complete (1 x)–

Includes: Removing and fitting spoiler lips on front apron, removing rear
spoiler drive, partially disassembling rear lid and fitting rear
spoiler.

Labor time: 340 TU
May

[BillC]

Originally Posted by OttoBurgess

billc you have me scratching my head now

what is the difference between less lift and more down force?

"Less lift" means you have reduced the normal aerodynamic lift of the car, but haven't reduced it to zero. "More downforce" means that you have not only completely countered the normal aerodynamic lift but are actually generating a net downward aerodynamic force pressing the car to the race track. Basically, the two phrases are describing the same thing, but they are relative to which side of '"zero" the car is on.

Originally Posted by OttoBurgess

however, i could feel the rear end lift and the front end dance at speeds approaching 130mph at various points on track - so much so that i backed off a bit several times

Getting light at both ends means the car is still fairly well balanced. Adding a better wing or spoiler at the back without doing something on the front will actually make your front-end lift worse, not better.

[roundel]

buy a Redbull. Its cheaper and easier to install.