Flight 997.2

I'm considering adding a Cayman GT4-style wing to my platinum silver 2013 Boxster S (manual, with black top & interior).

The body is currently stock but I plan to add black “PORSCHE” stripes at the bottom door edges soon. My current wheels are a Carrera style, 19", polished silver, and I think I’ll replace them with a different design in matte-finish, light gray color, 20”, before very long. My main interest in adding this wing is cosmetic. I’d say the car now has a “polished elegance” flavor, and I’m migrating toward more of a performance look. The wing I’m considering is made by NR Auto (same ownership as Winn Automotive). It’s available in ABS, but I’d go for their carbon fiber version. I’ve never tracked the car, but might someday if I find/make the time. The majority of my most spirited driving is on canyon roads that my wife and I seek out on trips to Colorado, Arizona and California. I prefer the tighter twisties, so cornering is rarely over about 60 MPH. I’ve had the car near its limit in a straight line a few times, and will want to do that again, but it’s a rare occurrence, in desolated spots like the grasslands of western Kansas or eastern Colorado.

My main QUESTION is this: If you were adding this wing, which is so much larger than the stock one (and sits higher, presumably in more airflow), would you consider it important to add a splitter at the front at the same time, to keep downforce at the front correct? (Note that I would disable the stock wing’s auto-lift.) The mfg. doesn’t make a front splitter and says they don’t think most people who add this wing add anything at the front. Appearance-wise I like the front end just as it is, and for driveway entries I really wouldn't want to add anything that reduced front clearance. Almost all photos I can find of this wing show it on a Cayman. It looks to me like the mounting surface on a Cayman is a little steeper than on my Boxster. Other questions, while we’re at it: Should I expect any appreciable increase in wind noise? Also, I’ve never bought any body part like this in CF; other than cost, does the material come with any disadvantages over painted ABS? Opinions—positive or negative—of how you think this wing would look on a silver 981 Boxster, are also very welcome.

Again, my main question is about the need for a front splitter, if mounting this larger wing. I’m inclined to think that the front end will be fine as it is, but would appreciate others’ thoughts and/or experience.The wing-only photos below are the actual wing I'm considering. The on-car images show the same wing but in painted ABS.

Reborn996

I think you are also missing the fact that the rear hatch had to be reinforced on the GT4 to handle the additional downforce pressure for that type of wing.

I can also say that the front and rear Aero balance on the GT4 requires a change in the front splitter when adjusting the attack angle on the rear wing to keep safe handling. It is a very intricate balance.

I would not recommend adding this wing without proper front Aero to balance it out. You don't want excessive rear downforce at speed creating understeer.

Flight 997.2

Thanks Reborn996. I wonder how much difference it makes that this wing sits quite a lot lower than the actual GT4, and also that (I think) its angle on the Boxster would be quite a bit flatter. I've also considered seeing if I could modify the wing's angle, to reduce its effect to ~equal that of the stock wing. I'm not sure what such an angle mod would require, but I've rarely encountered something I couldn't tweak.

I guess I should add that said tweaks aren't beneficial exactly 100% of the time. :-)

I was thinking that I might tie a string onto the existing wing to determine approximate airflow direction, and do the same with the new wing (photographing each from the side during driving), calculate the area of each wing that's "frontal" to the flow at those angles, and then, if necessary, flatten the angle of the larger wing (or, conceivably, make it steeper).

Or to get really ambitious about it, I could replicate the top surface of the OEM wing, put that on a scale, mount it to something like the top of my Suburban's luggage rack (perhaps on a forward extension to get into clean air) with a scale underneath, drive about 80, and monitor the scale readout remotely. Then do the same with the new wing, and adjust its angle to match the scale reading that the OEM produced.

I also happen to have a fan made for aerating grain bins that, with a suitable plenum chamber, might create enough flow for such a comparison.

Pep!RRRR

Reborn996

The OP did say he may track the car and has driven it to the limit on long straights so I doubt it will stay under 90MPH after the wing install.

tomhartzell

Agree with Reborn996. Porsche offers a wing kit for the 987.2 Caymans, and the front spoiler that comes with the kit must be installed when the aerokit wing is installed. (https://www.suncoastparts.com/product/987C2AERO.html -- no affiliation)

Airflow over, under and around the cars at high speeds is a critical design component for each Porsche. While I think it would look awesome, I would be very reluctant to drive the car any faster than highway speeds if it had only the wing but not the front spoiler – even if it were a wing designed by Porsche. (And would be real interested in knowing if the enhanced downforce in the rear would adversely affect the steering even on the highway.)

Flight 997.2

I was thinking, earlier, that a flatter mounting angle (as I think it would be on the Boxster, vs. a Cayman) would result in a less aggressive wing. But I realized just now that it's the opposite. So that's something I'd need to try to adjust for, I think. It seems like wedges between the struts and the wing might be the best way to adjust the angle.

Reborn 996's observation about the Cayman's hatch being reinforced for the GT4 wing is good to know. There's a gap between the upper and lower sheets comprising the lid in that area. I wonder if the mounting bolts go through both sheets; I would think so. If so, some ~1" nylon spools over the bolts between the two sheets would support the upper sheet greatly, I think. An additional hole would have to be drilled to get the spools into the space; I don't think the access hole would compromise the lid at all.

Flight 997.2

Significant point, thanks.

Just to be clear, I definitely haven't settled on adding a wing at all. Skipping the CF wing would certainly go a long way toward paying for new 20" wheels and tires!

This TechArt wing is also in the running. It's smaller and positioned closer to where the Porsche wing operates.

MidEngineRules

I'm thinking aero is not interchangeable between the Cayman and Boxster based on the sizable roof shape/size differences. Otherwise you'd see shared methods of rear downforce, which you definitely don't. Just go with the Spyder's duck tail and surrender to Porsche's actual extensive aero engineering. Would probably still need to add downforce to the front end. Personally I think a fixed wing looks ridiculous on a Boxster. Thankfully Porsche does too since they've never offered one.

Flight 997.2

MidEngineRules: Appreciate the candor.

manifold danger

As I've always said, to each their own. It's your car, you do what you like to it.

But since you asked...

I have to agree with MidEngineRules. Seeing the photo of the convertible "GT4" kind of makes me squirm, to be honest.

And normally I'd chalk it up to "different strokes for different folks" if all we were talking about is aesthetics, but I think there's a legitimate concern with aerodynamics. If you have any intention of driving the car at speed then you have to consider the scientific aspect. Will it make a huge difference? Probably not... but unless you're just really looking to make your car stand out, I'd leave it to the Porsche engineers.

Make no mistake though, the wing will make your car stand out, if that's what you're after.

FWIW the TechArt wing in that last pic seems much more reasonable- but kind of redundant as it literally sits just above the factory rear spoiler.

Pep!RRRR

PorscheAddict

Agree with the others. A fixed wing looks awful on the Boxster, but the duck tail does not. You don't necessarily have to reinforce the rear to use a GT4 style wing, but aero balance will be off at >90 MPH and it will look like crap to most Porsche enthusiasts. In converting a M3 to a racecar years ago I put a wing much larger and higher than a GT4 wing without reinforcing the decklid and it held up for years. It's your car, do what you like.

Leicht

PorscheAddict

Not in any significant way. Even the GT4 wing only adds <200 pounds of force at 100 MPH. Exponentially more at higher speeds, of course.