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After market spoilers


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I have had my new (to me) boxster less than a month, and have already been elbow deep in the engine housing and stereo. Was thinking of changing out the factory "wing" next, with these aftermarket spoilers. I was wondering if they would do what they should for handling, however, since the factory model is solid, and these allow airflow underneath, rather than damming it and holding the rear end down. I am no engineer, so if anyone has any experience or thoughts, I thank you in advance!

post-12657-1155055852_thumb.jpg

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I wouldn't get too hung up on aero impact unless you will be doing alot well north of 100mph.......personally I'd say they are more about bling and just what you want the car to look like (standing still).

Personally I've never cared much for 'moving' rear wings on Pcars......if I added a wing I would disable or remove the 'mover'.

Good luck to ya.......enjoy your car!

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I wouldn't just because it shouts "look at me, I'm trying to attract attention".

I've done subtle mods like tail lights and sidelights but aero kits and side skirts and spoilers and speedster humps just make no sense to me.

But it is your car and if that is the sort of look you prefer, go to it. People have different tastes and that is why they make cars in multiple colors.

As to the impact on airflow, it is negligible at any reasonable street speed. Above that I'd bet it does have a negative effect as it would disturb the flow coming off the stock spoiler.

Something to consider, does it attract attention in a way that is going to draw unwanted attention...from thieves or cops?

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I know when i was looking at buying a Noble M12 a lot of the owners were having trouble with the front lip catching on speed humps and the like.

The owners club spoke to Noble about the effects of remving the lip, and they said it didnt have any effect under 120mph! so goes to show a lot of these things are merely cosmetic until you take on a track

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I added this wing because I like the look of it on the Cayman. I'm not about bling; just think it updates the look on the car. BTW, I get alot of compliments and our Chicago National Concours judge/champion liked it so much, he ordered one.

post-10990-1155137612_thumb.jpg

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I added this wing because I like the look of it on the Cayman. I'm not about bling; just think it updates the look on the car. BTW, I get alot of compliments and our Chicago National Concours judge/champion liked it so much, he ordered one.

Wow, I think it looks great!

So, is it aftermarket, or cayman one? How much did it cost?

Was it complicated to change?

Saludos

Kare, Spain

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I have had my new (to me) boxster less than a month, and have already been elbow deep in the engine housing and stereo. Was thinking of changing out the factory "wing" next, with these aftermarket spoilers. I was wondering if they would do what they should for handling, however, since the factory model is solid, and these allow airflow underneath, rather than damming it and holding the rear end down. I am no engineer, so if anyone has any experience or thoughts, I thank you in advance!

I was debating whether or not changing this would upset the aerodynamic balance at speed as well (I do take some short runs "at speed" now and then). Then I realized something - Ruf doesn't touch the rear wing on the Boxster in their mods. If it's good enough for Ruf to leave alone, it's good enough for me to leave alone. End of debate. Stock wing is still there.

These are my thoughts. I'm not an aerodynamicist, but I do have a bit of history with drag racing cars and their aerodynamics. The Boxster has a VERY low drag coefficient. It is slippery through the air. A car can't be that slippery without managing the airflow element of the design. It seems to me that the Boxster rear wing is designed either to keep the airflow over the back of the car from causing a turbulent zone to exist too close to the back of the car (at high speeds,) or to keep the airflow over the car from becoming higher velocity than the airflow under the car, as this would cause some degree of lift I would think. Without the spoiler raising up and causing the air flow to move up away from the deck lid a bit, it might be that the airflow over and under the car would become imbalanced and things could get a bit dicey. This, of course, is irrelevant at speeds under maybe 80 to 100mph. I just don't think I'd like to find out if I am right or not at say 130 or 140. Again, the fact that Ruf doesn't change a thing back there speaks volumes to me.

The double wing setup does look hot, but since the wings allow airflow both over and under them, I don't see how they could possibly achieve the same affect aerodynamically, although I concede that it might be enough to avoid anything nasty hapening. I have kind of stayed away from any rear wing change because of that.

Any aerodynamicists lurking around here ?

Edited by Andy_M
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How about the carbon fiber spoiler on the Cayman 3.8L GTR in Excellence Mag in September?

5162006131238.jpg

Thats what I want...

Notice that the Caymen has a base spoiler, at the same angle as the riser spoiler. The two work together to direct the airflow up off the deck lid at speed. Putting the riser spoiler alone on a Boxster would not acheive the same aerodynamic affect ,since the second spoiler is missing. . .

Of course, if looks are the only concern, I guess it doesn't really matter.

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How about the carbon fiber spoiler on the Cayman 3.8L GTR in Excellence Mag in September?

5162006131238.jpg

Thats what I want...

Notice that the Caymen has a base spoiler, at the same angle as the riser spoiler. The two work together to direct the airflow up off the deck lid at speed. Putting the riser spoiler alone on a Boxster would not acheive the same aerodynamic affect ,since the second spoiler is missing. . .

Of course, if looks are the only concern, I guess it doesn't really matter.

This is true, however a boxster is only capable of 159 or so MPH which is pretty slow. I doubt a spoiler or no spoiler would make any difference on a car with that low of a top speed. It might be slightly more stable but it's not like the effect of a spoiler on a 175mph car.

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My Boxster is a street car that's never been over 95 mph. When I want to drive fast, I take my 911 to the race track. The lip is very subtle when in the lowered position (I had just installed the sport muffler and took the pic, forgetting to lower the spoiler). Just enough to make it look slightly different and not jump out at you. I'll post some more pics when I have a chance. BTW, you can buy them on eBay, pre-painted. Takes about twenty minutes to install, at the most.

Edited by jmatta
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Porsche considers the pop-up spoiler essential to the car's stability at higher speeds. Note that Porsche put a warning light in the dashboard that illuminates when there is a problem raising the spoiler. That indicates the importance they place on the spoiler. I wouldn't mess with this. Why would you sacrifice functionality and safety for looks?

Gary

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Porsche considers the pop-up spoiler essential to the car's stability at higher speeds. Note that Porsche put a warning light in the dashboard that illuminates when there is a problem raising the spoiler. That indicates the importance they place on the spoiler. I wouldn't mess with this. Why would you sacrifice functionality and safety for looks?

Gary

And that, Gary, is mostly where this debate lies: whether or not the functionality of the spoiler is undermined (at least it's what I had hoped to learn in this link) at normal driving speeds. I don't suspect anyone reading this thread is hoping to themselves "jeez, I want an aftermarket spoiler, but I hope it works well in directing air flow when I'm driving 145mph down I-80". The spoiler pops up at 75mph automatically, which, one would assume, is a conservative speed (in terms of the spoiler being truly necessary) as dictated by Porsche. I, personally, never go over 90, which probably isn't brilliant in itself, since all speed limits in urban Dallas are, at most, 60.

When I saw the pre-painted spoilers on ebay, I liked the way they looked in the pics, and my main concern was the paint match and fitment, not safety at normal driving speeds.

Actually, I hope someone else purchases and installs these spoilers and takes some close-up pics, so I can decide whether or not my (like most Porsche owners) perfectionism will be satisfied by a large and very ostensible aftermarket add-on.

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Here's a couple more of my dusty car...the sun angle was brutal, so they're not the best, but it gives you an idea.

Here's a couple more of my dusty car...the sun angle was brutal, so they're not the best, but it gives you an idea.

One more...

post-10990-1155684880_thumb.jpg

post-10990-1155684910_thumb.jpg

post-10990-1155685120_thumb.jpg

Edited by jmatta
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Here's a couple more of my dusty car...the sun angle was brutal, so they're not the best, but it gives you an idea.

Here's a couple more of my dusty car...the sun angle was brutal, so they're not the best, but it gives you an idea.

One more...

The spoiler looks fantastic!

Is your spoiler a standard Cayman one? How much did it cost?

And any difficulties on installing it?

Kare

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The Porsche engineers,

after wind tunnel and track testing decided that the shape of the spoiler for the Cayman needed to be different than for the 987 Boxster.

Do you suppose that they did the same for the Cayman spoiler on the Boxster and rejected it as an alternative because it didn't do the job as effectively?

Do you suppose the after market folks ever really test their products beyond "will it sell"?

The presumption that we know better than the engineers based on what looks good to our eye obviously bothers me.

Lots of places the real speed is over the 75 MPH deploy point. I-95 up the east coast last Sunday would have seen deployment 90% of the time.

At 90 MPH, will it make a big difference? Under what conditions? Who knows and I'll bet the makes of the spoilers don't either.

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I don't suspect anyone reading this thread is hoping to themselves "jeez, I want an aftermarket spoiler, but I hope it works well in directing air flow when I'm driving 145mph down I-80".

My reply was mainly directed at 986Jim's post, which suggested that up to 160mph the spoiler's contribution to downforce is negligible. I strongly disagree with his conjecture.

Is there a noticeable difference in downforce between the factory spoiler and the aftermarket ones at speeds below 90mph? Probably not, but that is just a guess. Without expensive test equipment nobody will be able to tell you exactly. Seat-of-the-pants experiences will only be approximative.

Given that exact information is not available, and the potential safety issues, I personally don't think it's a very good idea to second-guess the factory. But again, that is just MHO.

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Ah, in an (perhaps futile) attempt to summarize, I'll make a few concessions:

-I hope that no one on this forum believes an aftermarket spoiler is better, aerodynamically, than the specific spoiler the car came with (at the point that porsche determines it should deploy)

-As far as aesthetics go, it's entirely too subjective on whether or not you find the spoilers good-looking or not, if you do, great...if not, don't buy one

-I, personally, do not drive over 75mph very often, and although I have an English degree and never took a single engineering course, my (potentially retarded) feeling is that even at 90mph, the aerodynamic benefits of an OEM spoiler that Porsche dictated should only have deployed 15mph ago are nearly negligible

-At the same time that I know zilch about aerodynamics, I still think I would be retarded to think that the downforce wouldn't have SOME benefit at, say, 110mph or higher (but I like safety and dislike law enforcement, so I'll resist the temptation)

-Now that I have rambled on and on, I realize I could have simply said: I will probably buy one because I like the way it looks, and I do not drive fast enough (in my opinion) to feel I am sacrificing safety for aesthetic individuality

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Next time I drive 150 mph+ down I-94, I'll be certain to invite a Porsche aerodynamicist to ride with me so that he can advise the impact an aftermarker spoiler has on my car's balance. Until then, I will drive at safe highway speeds and leave my high speed work to Road America in my 911 (which by the way has a ducktail, which we all know is not as efficient as the larger, more modern spoilers).

All in jest...

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Hey guys, newbie here who has been lurking for awhile...had to add to this....I know I read that the spoiler does not produce downforce. What is does do is reduce UPLIFT on the rear end, which builds as speed increases due the the very "winglike" profile of the car. At 90 mph it reduces rear axle lift by 30%. Obviously as speeds increase, the reduction also increases.

Interestingly enough, I researched this question (after I bought and installed the spoiler in question because I thought it looked cool).......and after finding out about the uplift I removed it, sold it, and went back to stock.

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pecivil is right, the spoiler on the boxster is a true spoiler in that it spoils the air coming over the top of the car, producing drag and reducing lift. What most people call a spoiler is actually an airfoil. Basically an upside down airplane wing that produces a downward force on the car.

http://www.answers.com/spoiler

http://www.answers.com/airfoil

The lift equation is ( velocity squared ) * ( coefficient of lift ) * ( surface area ) * ( density of air / 2 )

Notice that velocity is squared. This means a tiny 15mph change between 75 and 90mph is actually a 225mphph change as far as lift is concerned. Also note that the 'tiny' 15mph change is a 20% increase in speed. In planes, 15mph can be the difference between airborn and on the ground.

See Also: http://www.grc.nasa.gov/WWW/K-12/airplane/foil2.html

(In addition to being a Boxster owner, I'm also a pilot so I've studied lift quite a bit)

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Next time I drive 150 mph+ down I-94, I'll be certain to invite a Porsche aerodynamicist to ride with me so that he can advise the impact an aftermarker spoiler has on my car's balance........

All in jest...

...and that's exactly where I was coming from on this. If you don't track the car, or drive at high speed- EVER - than put what ever the heck you want on there...it doesn't make a **** bit of difference.

If you track the car though, and don't happen to have a spare 911 hanging around :P , you could find yourself getting an unpleasent suprise thrown at you in a high speed corner somewhere if you have played with the wing. Maybe it's only a DE event, or a club run, but the speeds are track speeds, not 90mph....and if you don't think (as one guy here suggested) that aerodynamics play a BIG part in handling and stability at a "slow" 157 mph......... :censored:

P.S guys...the difference between 75 mph and 95 mph, aerodynamically, IS significant, because the effect of the air velocity is squared as Binaryc pointed out in his post. Removing the "daming" effect of the stock rear spoiler will have the effect (at speed) of increasing the rate of airflow over the TOP of the car while the airflow under the car remains the same. This causes a pressure imbalance that creates a LIFT vector...that last thing you want to have at high speeds - unless of course you wish to fly (quite literally.) The faster you go, the stronger the lift force gets. :help:

Bottom line...... if you track the car, or plan on doing some DE's, leave the stock spoiler in place. If not, and everyday driving, fun runs, maybe a little AX, is the extent of your Boxster experience - then throw on there whatever floats your boat. It isn't going to change the handling at all.

Edited by Andy_M
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Binaryc,

What you say is true. Aerodynamic forces are significant on a Boxter well below 100mph. It has been a while since I read the wind tunnel test data on this car but I remember the stock spoiler was very effective at neutralizing lift and even improved the drag coefficient by spoiling the eddy behind the car. Before I add a wing or aftermarket spoiler I would need some assurance that it was designed and engineered for my car and would still do the job of keeping the rubber on the road. I see all these EVO's and WRX boy racers running around with homemade wings bolted onto their trunk lids and wonder quietly at what speed they will achieve liftoff. Eye candy at what price??

I don't see much track time anymore but on a beautiful Autumn day when presented with a long stretch of barren road I just might wind up my Boxter a bit. I don't want to worry that my car might suddenly become an airplane. One of the best /worst examples of aerodynamic lift was the original Ford GT40. This was an amazing car in its day... capable of 200mph it won Le Mans 1,2,3 in 1968 but was a very frightining ride at speed. Under the right conditions it would begin to fly at 120mph. Yikes!

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