Factory wing

Can someone tell me the width of the factory wing? I'm guessing either 67" or 72" but, would appreciate if someone could tell me for sure. Thanks!

IIRC its actually HUGE @ 86" but offhand i cant remember exactly

You were very close. My measured 68.5" wide.

Thanks Jerry for the confirmation.

I was interested because, in addition to needing a nose for the car, I also need wing....


Eric - is it just the angle of the picture or, is your wing postioned higher that the roof line of the car?

Thanks Jerry for the confirmation.

I was interested because, in addition to needing a nose for the car, I also need wing....


Eric - is it just the angle of the picture or, is your wing postioned higher that the roof line of the car?

Just the angle, it actually sits flush with the roofline

I was told at the track this weekend by a team who owns several GTS's that our wing is worthless for creating downforce and we should throw them in the trash and get a real wing. Not sure how I feel about that.

I was told at the track this weekend by a team who owns several GTS's that our wing is worthless for creating downforce and we should throw them in the trash and get a real wing. Not sure how I feel about that.

From earlier threads, it seems that a good front splitter (a la Kel) and repositioning the original wing (a la Eric's adjustable mounts) can be significant. In the stock location the wing adds weight and some drag, but little more downforce because it is not in the air flow. Wasn't it Eric who lost a repositioned wing and almost crashed due to a sudden loss of rear down force?

At the Texas Mile last Spring, Al Lamb ran his GTS, SCCA GT2 car, with and without the wing. He hit the rev limiter both times (168 mph trap), but he hit it 200 yards earlier without the wing and noticed no change in straight line stability. Drag is a factor at high speeds.

Maybe Kel and Eric can restate their experiences concerning splitters and repositioned wings vs. the original air dam and wing location under track conditions.

In SCCA the dam and wing must be as delivered. Other series probably have greater latitude.

Mike

As much as I would like to categorically state/confirm that raising the wing and adding the splitter have reduced lap times by X amount each, it is difficult for me to do so. I did post feedback at the time providing estimated improvements but have not recorded this in my running log so cannot break out again at this stage.

You all know the old racing cardinal rule of making one change at a time........ Unfortunately reality of time pressures dictated that I had to make several changes at once to get the car ready for the last endurance season.

What I can say is that we started out with a car that was being pushed to the limit (resulting in several off track excursions and broken plastic air dams......) to do 1.12 - 1.13 lap times at my local circuit on a mix of DOT's and slicks. The engine/chassis and aero changes combined to reduce these times to comfortable 1.07 - 1.08's with the car being absolutely stable and predictable. We were able to race mainly in the 1.08 - 1.09 bracket for 6 hours with no drama's for the 3 drivers. The car responded positively to all aero changes made and nothing was changed back as a result.

I am planning future aero mods, the first being a gurney flap for the wing for running in the wet. This has been made and (drag) tested but not run as all running has been in the dry so far. The gurney flap did not impact straightline speed that we could detect. Second aero mod will be lowering the splitter and changing its angle of attack. I expect this to significantly enhance the splitters performance. Lastly we are looking at adding a diffuser to the rear of the car. No development work has been done on this as yet and it is unlikely that it will be ready for this season but research is under way.

Kel.

I would argue that the wing is WORTHLESS, but I will agree thats it's a high drag low downforce design. I have run some basic 2D CFD tests on the height, and angle of the spoiler to get some basic data, I have real world wind tunnel tested it but the design is a basic reverse "air plane wing" and does create downforce...

Here is a quick graphic of some of the CFD tests I've done. Once the LSx Swap is done my next "mod" is a more productive wing design

Sorry for the large pic But if you look REALLLLLLLY close, you can see the pressure difference just above the spoiler in the right side pics...

http://www.extremespeedonline.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=96240&g2_serialNumber=1

Ohhh, and yes, I had the best possible "real world test" My wings bolts sheered off at 120mph on the uphill S's at VIR, and it was easy to feel the difference the lack of spoiler made through the highspeed winding turns..

I guess what you are saying Eric, is that when raised up the factory wing does produce downforce (amount unknown) but there are more efficient designs out there (from a downforce Vs drag perspective)?

Have you seen a design that you think would be a good fit for our cars?

There are a couple of wings commonly used out here by other endurance competitors on high powered cars. I will pay more attention to these and get a photo and brand to post.

Kel.

Guys, when we moved the wing and added a splitter we did notice the added downforce. I think the other teams was pushing that our wing is junk and we should buy a comp coupe or cup car wing (I think we need a larger wing) and bolt that on for some real aero.

I actually really like the APR GTC-500, I had the GTC-300 on my BMW and it had MASSIVE downforce, and very low drag. my top speeds were only 1-2mph different MAX at the end of the long straights at VIR and the grip level was amazing....

The rear of the car has 900lb spring and its squating down a good 1-1.5"

http://www.extremespeedonline.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=90963&g2_serialNumber=2

Here is some CFD data for the GTC-500...

Its a good length @ 70"

http://www.aprperformance.com/index.php?option=com_content&task=view&id=182

I worked pretty closely with APR on the GTC-300 design for the BMW, great guys to work with

thats a big passenger in there - looks like Graham. LOL

A bit off of the subject, but has anyone cut large holes in the bumer of the Panoz to reduce the parachute effect caused by the rear bumper cover? I've seen several Porsche's with their rear bumper swiss-cheesed to allow the air to flow out from the pocket behind the fuel cell. This is similar to cutting a few holes in the rear window to allow better flow out of the driver cabin. An alternative coud be to create a diffuser. Any thoughts on which one might be better, or more effective?

i will be cutting holes. not sure where and how many yet but the hole saw and jig saw will be used.

A bit off of the subject, but has anyone cut large holes in the bumer of the Panoz to reduce the parachute effect caused by the rear bumper cover? I've seen several Porsche's with their rear bumper swiss-cheesed to allow the air to flow out from the pocket behind the fuel cell. This is similar to cutting a few holes in the rear window to allow better flow out of the driver cabin. An alternative coud be to create a diffuser. Any thoughts on which one might be better, or more effective?

Jerry, this was the first aero mod that I did to the car. After having the trunk lid half blow off while racing I used a hole saw to cut a row of holes across the back lower edge of the car as can be seen in the photo below.

http://i427.photobucket.com/albums/pp355/NZGTRA/Panozdynosession8Nov08003.jpg

I did this in combination with other changes but have had no more issues with the trunk lid. I have not had a chance to measure pressure in this area at speed.

Personally if I had the choice between this mod and a diffuser I would add a diffuser as it will certainly be more effective aerodynamically. Cutting the holes is more of a band aid in my view - but it works and costs virtually nothing. A pro diffuser will cost you around US$750 if made from carbon fibre.

Kel.

Kel – I’ve been giving thought to a diffuser as well and, it seems to me that to gain maximum benefit of a diffuser (enough to warrant purchase and installation) we need to consider a simple under tray to smooth the airflow under the car. I don’t think this would be that difficult and wouldn’t need to go the extent of sealing wheel wells etc. but, probably needs to be considered as part of the package. Thoughts?

update:
After thinking about this further, unless the diffuser tray could extend far enough forward or an under tray far enough back to channel the airflow cleanly past the rear diff and rearwheel openings, I'm not sure the diffuser will give maximum benefit?? Think about a smooth underbody from the front splitter back to where the cockpit enclosure ends, (about where your battery is mounted.) which wouldn't be that hard to do. That smooth underside would speed up air flow under the car creating low pressure with at least some downforce as the result. But, once the airflow reaches the void toward the back of the car it would seem that it would get pretty distorted rather than flow smoothly past the diff and rear wheel wells etc. and thru a diffuser??? Not sure how much that would diminish the value of a diffuser or worse, create instability?

Kel, thanks for the pictures. I like the modification you've made to the bumper. Good to hear that it has been effective. What do you think about cutting 6" diameter holes in the flat part of the bumper cover? I assume that the flat portion of the bumper would be the highest pressure region on the cover. I don't have any flow calculations to prove my assumption, just that air caught in the fuel cell region is turned on that surface. The turning of the air could cause a pressure peak. Why 6" holes? Well that's the biggest hole saw that I can find.

I agree with Gary. I've had similar thoughts on what would be needed to create low pressure under the car. Until you smooth out the undertray of the entire length of the car and seal off the volume around the fuel cell, I don't think you'll get the full intended results from a diffuser. I seen pictures of the extent that the aero guys go to for ALMS racers like the Ferrari, or Corvette. The under tray is a work of art. All I'm certain about is that I don't have that kind of budget.

So it's low budget hole saw time.

Kel, thanks for the pictures. I like the modification you've made to the bumper. Good to hear that it has been effective. What do you think about cutting 6" diameter holes in the flat part of the bumper cover? I assume that the flat portion of the bumper would be the highest pressure region on the cover. I don't have any flow calculations to prove my assumption, just that air caught in the fuel cell region is turned on that surface. The turning of the air could cause a pressure peak. Why 6" holes? Well that's the biggest hole saw that I can find.

I agree with Gary. I've had similar thoughts on what would be needed to create low pressure under the car. Until you smooth out the undertray of the entire length of the car and seal off the volume around the fuel cell, I don't think you'll get the full intended results from a diffuser. I seen pictures of the extent that the aero guys go to for ALMS racers like the Ferrari, or Corvette. The under tray is a work of art. All I'm certain about is that I don't have that kind of budget.

So it's low budget hole saw time.


I agree that the pressure under the trunk lid is great. On my sports racer
with the areo package I installed fiberglass louvers on the engine lid. On the Panoz I used a 4" plastic dryer vent from Lowe's on the rear lid very cheap and works very well. Cut one hole and you are done.

I seen pictures of the extent that the aero guys go to for ALMS racers like the Ferrari, or Corvette. The under tray is a work of art. All I'm certain about is that I don't have that kind of budget.


The benefit these race cars have, in addition to budget and technical resources, is that most if not all run a transaxle arrangement and can get an under tray in place without worrying about dealing with a big ole floating (Ford) 9" rear end housing.

The unit below is an Emco Gears unit used by a lot of the Grand-Am series cars. A lot easier to run a tray under that unit and only worry about Axles/CV joints exiting at either side.

The question that remains for me is - is there any benefit to at least a partial undertray that stops short of the diff and fuel cell area????



http://www.ppiclients.com/profiles/115_12_1.jpg

Gary, Jerry,
I dont have a hoist in my garage so I am not well equipped at this stage to panel up the whole underside of the car. I was looking at trying a diffuser on its own for a start. I suspect that this will still produce worthwhile results but that panelling the underside would further enhance the diffusers efficiency.

Kel.

Kel - I'd love to hear any results if you happen to go that route. I'm still struggling with how it would work. What I am struggling with is this:

To my understanding, the purpose of the diffuser is to slow the air (that has been accelerated under the car so that its higher speed can produce a lower pressure under the car and ultimately some downforce) as it exits the rear of the car and blend it in behind the car closer to the same speed and pressure it was before the car ran into it.

Having said that, it seems to me that if we don't have a means to substantively increase the speed of the air travelling under the car (via splitter and smooth undertray or the like) we have less of a need (maybe none??) for a diffuser to slow it down on exit?

I'd really like to get some definative info on this. Anybody have a bother-in-law who happens to be an aerodynamicist??? J