IanM

Well yes, there's no certainty on the magnitude of additional downforce (and drag) something like this will create unless it's designed using a Computational Fluid Dynamics model and/or tested and rebuilt iteratively using a track or windtunnel. It's safe to bet on some extra downforce. I also agree that it looks great, as does the wing addition on that white M3.

Here's an example of a basic 90 degree gurney flap on a simple (shape-wise) wing -

kk2

Can you show us your test results that prove it's ineffectiveness?

Concept and execution of a gurney flap is pretty damn simple. Aerodynamics of a car aren't that hard to understand and improving on an existing design is relatively easy to do. This is exactly uncharted territory.

IanM

As far as I know, there are 3 main items of importance when it comes to gurney flaps -

(1) the flap should project perpendicular to the top surface of the wing

(2) the vertical plane of the flap should be placed right at the trailing edge of the wing

(3) the height of the flap should be between 2% - 5% of the wing chord (width) - Joe has shaved it down slightly from the photos above and is now at 3.5%, in order to maximize the downforce benefit without adding much drag

IanM

Update - Joe is building his mold directly on my wing, to assure a perfect fit. I understand from him that twisting/warping could otherwise be an issue when producing such a small part. I hope my wing comes out of this unscathed! I've been driving around for a couple weeks now with no wing, it looks pretty goofy with just the uprights.

ScottArizona

Looks good. You know what product he could fab that would likely sell great? The ram air ducts for the lower engine lid (like the 996 rs). Fvd sells one but its crazy expensive, and the cheaper alternatives don't fit we'll I'm told. Just a thought!

IanM

Yes, agreed. If you look at the first page you'll see I've got a ram air duct on the car. It's really on there, I don't think I could pull it off without damaging the paint.

kgorman

I am really not trying to be argumentative here. But your asking me to prove a negative on a part someone else makes? The value prop of the part is the responsibility of the vendor.

I am familiar with a gurney flap, what I am asking for is proof *that* part provides an aero advantage. Serious, just do some coast down testing even, anything. Some data other than a picture of someone else's flap. Or call it a cosmetic part and we are good.

Karl996

I'd be in for the ram air duct

DER951

^^

+1

Joe Toth

Guys I'd like to chime in here. Please do not read this as if I am mad or upset. I'm too old and comfortable with what I do to be offended. I am neither an aero engineer nor a vendor. Just a dumb *** moldmaker who likes to fool around with composites in his spare time. Maybe I don't smell enough resin fumes during the day at my regular job and need more of a fix after hours. Ian asked if I would be interested in making a Gurney flap for his car and my response was YES what the heck I've got nothing better at this five minutes. Don"t know if it will help the aero on his car and frankly don't care. IT SURE AS HELL LOOKS GOOD. We are taking a proven principle and modifying it to fit his wing. I strongly feel there will be some benifit but without a wind tunnel who knows. Maybe it will have a placebo effect when Ian is on track thinking the part is helping and he'll go faster. Who knows. I build this stuff for fun and some folks like my designs. The original GT3 splitter I gave Ian sat around for two years in my shop before I gave it to Ian. By all the feedback from happy drivers it works quite well. Thanks to all those folks using the part. The original 951 piece I built was strictly for myself as I was not happy with what was available in the market. People who saw it wanted one and I have been pleased to provide the parts to those folks. This is not a business and I'm not going to get rich making a few Porsche pieces. I enjoy doing this stuff and if there are people out there who like what they see and would like a part I am more than happy to make it for them. I'm not trying to convince people these parts are the best things since sliced bread and I won't lose sleep over not making a sale.

Anyways I hope you all enjoy the parts I make and what I'm working on.
Open to all suggestions of other pieces to make
Thanks
Joe.

ScottArizona

Very awesome response! Thanks Joe. Um, a ram air duct would be cool (but only if you can prove to me the relative volumetric pressure increase at the intake, subtracting of course the laminar coeffecient variable factor at an a given altitude/temperature!) (just kidding!).

DHI

Joe,
The forum is lucky to have such an accessible resource like you.
Most will appreciate the your time testing and making these parts and see this as a labor of love.

With that said, and for your consideration;

Ram air scoop is a no brainier.
For the track strippers...
CF dash. Nothing like that on the market right now.
Headlight assembly replacements (headlight dummy covers)

Joe Toth

Guys, I have a problem. Folks have asked me to make wings and the ram air scoop in the past. My problem is some one else already makes those parts. I hate copying. My original 951 splitter was copied in California and being sold as an original design. Needless to say I was not a happy camper. I don't want to infringe on others efforts and hard work. I wouldn't mind doing the scoop but it would have to be original. That said how different can you make a scoop or a wing. Let me think about the scoop and see if I can't come up with something.
Thanks for the support

DHI

Easy.
Make it bigger and more pronounced.
Original. Done.

bgiere

Thanks Joe, I have been very happy with the pieces you have made for me in the past! Keep up the good work!