let's talk downforce
 

ok, what really works for a dedicated HPDE track car. A 2006 Cayman S?

Getty Design seems to be the go-to solution and I've talked to people that have it and they say it works. but they now have a GS and RS wing and I can't find anything that talks about the differences. Anybody know? They look quite different.

I'd love a riser that doesn't require a duck-tail, but haven't found anything other than for the rash of GT4 knock-off wings, which seem more appropriate for a certain street look than actual track down force.

Any place that I should be looking-reading-calling? Doesn't of internet searches have come up quite dry.

And how about splitters? The getty Design splitters don't extend back under the car like the Body Motion splitters did. Any good choices?

If you get a wing, you will need a front splitter

Gt3 wing with stock or cup upright
Front lip off getty or bodymotion, all good

Attachment 1096325Attachment 1096324

Bodymotion splitters extending underneath is a well founded and fundamental aerodynamic proof. I've heard good things about Getty rear wings.

It's all about aero balance... easier to screw up than to enhance the performance of a stock GT car.

Everyone and their brother has an opinion on this, but there are some great tools to objectively quantify gain or loss.

To the OP: what problem are you trying to solve by adding aero parts?

It's not just about downforce. It is about aero balance, drag and downforce and there is no universal answer about what's best until you test and optimize. You WILL need a front splitter to balance whatever you do with a large rear wing. The Bodymotion Splitter works very well for that and it is sturdy.

The rear duckbill is great to attach the uprights to and makes the whole set-up sturdier - it is essential if you have a carbon fiber hatch. The old Cayman Interseries Wings were hollow (and therefore super light) and the uprights bolted directly to the metal decklid. Sone did break off so people used crossed piano wires to stabilize them. I am not sure whether the ITC wings are still made.

Most people set the rear wings high enough so you they see out the back window but keep in mind that the higher the wing, the more front pitching moment you will induce because of the wing's drag which will then cause high speed understeer. I use shock pods to calculate my aero forces and balance.

I just watched the inroduction of the new Honda NSX. According to the factory getting the aerodynamics right was the harders part. It took them 4 years to optimise it. 4 years!!!

it's a Japanese company. if you knew the politics at play- you would cringe on why it takes DECADES to get through the pipeline.
my wife's "okasa" (father) is an executive in a department. i saw pictures of the nsx years back that he shared w me. Honda GAVE him a NSX to daily drive for "marketing" :D - nice perks.

I ran the Getty wing on my old 987. Initially I paired it with the Aero-Kit front splitters. They were not adequate to balance the car and I replaced them with the Getty splitter. My data showed a loss of 2 or 3 mph at the end most long straights but lap times were a little better. I run WGI a lot and that was the reason for better aero plus it looks cool. I drilled additional holes in the wing support to flatten the wing for tracks without high speed corners. My car was street driven and the front splitter was a consumable.

no, its not about the drag of the wing at different hight levels , its how more efficient the wing will be at the higher positions. unless it goes rearward, there is no more drag for a high wing vs a low wing for the same amount of downforce.
PLUS, the main fact here is that the wing has a lift to drag ratio. we discussed at great lengths a while ago and the cup wing (which i use and have tested), hs a Lift to drag ratio of about 7-10:1. this means if you get 200lbs of downfrorce say at 120mph,the drag is 12lbs. hardly anything to write home about. Yes, if that 12lbs is 1 foot off the body or 2 feet off the body, the moment is still a very small rear downforce factor. the dowonforce is from the lift of the wing(negative lift) not the drag.

the spllitter, does what the name says, it splits the oncoming air to the sides and keeps it from going under the car.... underbody coverage is mainly a surface drag gainer, not a downforce aid. so, an air dam or splitter will do near the same thing, with the splitter being more effective.

It goes back to what problem are you trying to solve? if the car is loose on high speed turns, a wing can help. if it has a push , the wing will only make things worse. wings also can effect high speed front braking.. adding more rake can assist here if you dont have a splitter and only add a wing. it also can make a push worse in some of the medium speed turns (80mph) .




we have seen "data" that supports all sorts of things that are not possible. i have data of 2 -3 mile hour changes on a straight with no changes to the car. the reality is , the wing has no more than 150 to 200ls of downforce at WG if the speeds are in the 120mph range (you said you straighen the wing out for fast tracks) also keep in mind that the actual AOL of the wing is probably 9 -10 degrees higher than the setting , because of deflected air flow from the roof line . anyway, even if you are near max settings, the 150lbs of downforce, is 15lbs of drag. at 120mph , in 4th gear at a gear ratio of 4:1, thats near 3-4 lb-ft of torque at the engine. there is no way a 1% torque cost will cost 2-3 mph down any straight. think of it this way, if you made 4lb-ft of torue more on the engine at the dyno, would you expect 3mph more straight line speed ?

great that you are using shock pressure sensors, it would be interesting to see the before and after values both front and rear with and without the wing and splitter. we used pressure sensors on the rear hatch to see the effect of the cup wing. it was near 250lbs at 120mph. of course,with aero, these forces go up and down with the square of the speed, so at 60mph, downforce is only 60lbs (or 6 lbs of drag, and 1ft-lb of torque at the engine to drive it)

that getty wing is well designed for use on the porsche body. notice the reduced angle of attack taking into account the air flow deflection from the roofline. (yet the sides are higher AOA). wouldnt be very good to raise this kind of design wing up higher. thats when you go to a cup car wing.

I suspect Frank may have been referring to the lever effect of the wing due to the length of the uprights, and would have a tendency to lift the front of the car. This effect would increase as wing uprights get longer. I would have thought this was more due to the downforce at the rear due to the wing rather than the drag, but either way it's to be taken into account.

that was the "momemt" effect i was refering too as well. thats a drag thing. force rear ward, but tied to the radius of the wing and the rear tire. there is no "moment by going higher with downforce. you can have the wing 10 ft above the car and 100lbs of downforce is still 100lbs of downforce.. move it rearward, and the moment will increase. think lawnmower.... the handle futher back rearward increaes downforce in the rear for a given force. (more leverage) but height doesnt change this. same with the wing. drag is the only thing with a moment change with wing height.

True, as long as the longer uprights don't extend further rearward in addition to higher. They probably wouldn't though, so forget what I said :)

There are a couple answers to that question. (1) my brain has decided that my bank account isn't nearly bruised enough and this seems like a perfectly reasonable way to beat it up good and proper. (2) I want to get around tracks more quickly.

More specifically, I'm looking for more down force to help settle the car better over bumpy straights (T1->T2 at Palmer), more aero to help take fast corners with more speed/throttle (T2 @ Palmer, T2&T10 @WGI, Downhill @LRP etc.) and more grip on initial braking on long straights.

I'm already investing in coaching when I can (Pete A. at the Glen on Monday) and am still learning the craft of driving. More HP isn't going to help me much at this point because I mostly need to use more of what I already have in my Cayman S. I like my brakes (GiroDisks/Pagids) and tires (R7s). I'm doing 2:11 laps at the glen and 1:00 at LRP and would like to see if I can learn to put some aero to work for me.

Does that make sense? Where in your guys development did you jump to aero packages and why?

this is a common disease we all have it here
It takes a lot of aero to settle a car over bumpy areas, plus you need to be going real fast for it to help much. helps a little in the medium speed turns like what i see at limerock's final turn
you wont get much better initial breaking with rear wing additions, because at the higher speeds, its actuallly puting more force to the rear wheels and leaving the front (in most cases a little lighter) this is a trade off that some take to get better grip in the high speed turns. (trade offs) the reason is that you cant get the weight transfer to the front as quickly and as much with rear downforce.

I started to look at aero when i saw everyone else putting on big wings. :) but i also had a problem... a big push . the wing just made the push worse so i then worked on the splitter and when that didnt match the downforce balance goals, i added hood vents and still took more wing out. now its balanced . took a few weekends to dial it in and to understand the requirements for each track i visit. i then optimized the angles with some home built windtunnel type testing and seem to be working well now.
Ive driven the car with no arero, and the differences are noticeable ... its looser and has more push and doesnt feel as planted.

Are you extracting everything you can out of the current setup?

How much faster can a pro drive your car, and are you interested in closing that gap re. further skill development before jumping to aero bits?

Have you considered suspension improvements to meet your goals (what has been done so far) prior to aero?