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Track experience w/ C2 spoiler on earlier car

I know several guys here have C2 spoilers on thier earlier cars. I have the opportunity to get a C2 decklid with the retractable spoiler for my 85 Carrera. I know it can be mounted and read all the posts about hinge mods.

My question is this: Does it do any good, or does it really just end up being more show than go? The Carrera is stock, and I'd be putting a chin spoiler on to balance the load. Obviously, the C2 spoiler is smaller than the Carrera spoiler. AFAIK, this is because the aerodynamics of the C2 are so much better than the Carrera that it only needed a little spoiler to elimnate lift at the rear. My interest is purely practical - I like the looks of both the C2 and Carrera tails, and can go either way. My main interest is keeping the rear end planted at speed. I'm wondering if the Carrera spoiler is worth paying 3x the cost over the C2 wing that I can get.
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Old 07-22-2003, 08:52 AM
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I recall an article in Car and Driver ( hey, "Formerly Steve Wilkinson"....can you confirm?)...that the retractable C2 spoiler really didn't do much....more like "nothing". Anyone recall?
---Wil Ferch ( waiting for the rabid counter-points !!)
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Old 07-23-2003, 01:25 PM
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Yes, I recall that C&D article and I hope I can find time tonight to spend in the archives of my closet to find it. Read that mag cover to cover since I was 14 1/2.
Old 07-23-2003, 07:12 PM
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It's comparable to a ducktail, which is to say, it's only slightly less effective than a Carrera tail, with a less-detrimental effect on overall coefficient of drag.

See this link.

On a track car, I don't think either of the two tails you're talking about would be enough. If you want actual downforce, as opposed to merely reducing lift, get the 3.8 RS tail with extensions.
Old 07-23-2003, 08:45 PM
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Jack Olsen:

I expected to hear from you ..
Unfortunately...your link does not address what the C2 retractable spoiler does.
Unlike the previous spoilers that Porsche used...and that they graphically documented as part of testing... I see no such test results published by Porsche or anyone else for the C2 wing. The only documented and instrumented testing was the surprising Car and Driver article, which unfortunately said it did relatively nothing. Like you, I'd be interested in seeing valid counterpoints backed up in some scientific manner.

---Wil Ferch
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Old 07-24-2003, 06:10 AM
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I always thought it was roughly the same as the ducktail -- but maybe someone else on the board will have some data on this.
Old 07-24-2003, 10:21 AM
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OT..the raised shape of the C2 tail is nowhere as severe and pronounced as a duck. More like an earlier Carrera tail without the rubber "surround" piece atached.
I'll try to dig up the C&D article, unless others here do it before me.
---Wil Ferch
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Last edited by Wil Ferch; 07-24-2003 at 12:37 PM..
Old 07-24-2003, 11:31 AM
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Wil: I'd like to see that CD article as I have a C2 decklid waiting to be installed in place of my Carrera spoiler.

I don't want to start another aerodynamics discussion, but there has to be some benefit to the spoiler. Intuitively, it should work to some degree...and Porsche must have done a whole lot more testing than C&D!

I wonder if the CD tester made a qualitative statement. If they printed wind tunnel data, I'll be looking for a Carrera spoiler to replace the one I SOLD!! Grrrr!

Last edited by MotoSook; 07-24-2003 at 03:07 PM..
Old 07-24-2003, 12:10 PM
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I've driven a 911 with a stock lid, turbo tail, GT2 wing, and C2 flip wing. The C2 lid is marginally better than nothing. Never done a duck tail. The GT2 wing flat out rocks, and I'm sure Jack's wing is a couple notches better.
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Old 07-24-2003, 12:29 PM
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Damn! It's a good thing I can't go as fast as Thom or Jack....time to start shopping for a track wing!!!!!
Old 07-24-2003, 12:34 PM
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Souk:
Don't be so *sure* what Porsche did ( or did not) do to test the C2 tail. By that time "marketing" took on a bigger piece of the Porsche experience than did hard-core engineering. They were trying to capture those people that liked the look of the classic 911 shape...but maybe wanted some aero benefit at speed. The CD test, at least, was instrumented...something I haven't been able to find anywhere else. It was part of a larger article that asked the question if aero aids ( from *various* manufacturers) were GO or SHOW.
---Wil Ferch
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Old 07-24-2003, 12:41 PM
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Again, Damn!

Now I really want to see that article...
Old 07-24-2003, 01:04 PM
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According to "The 911 Story", a lot of the Carrera's tendency to lift at speed was engineered out of the 964. The bigger bumpers with integral spoiler, all the underbelly sheet metal, even redesigning how air flow over the engine was exhausted. At the end of it all, they were left with very little lift (compared to earlier cars) which was then neutralized with the pop up spoiler.

This leads me to believe that it might not be the best solution for an earlier car, but I wanted an opinion from someone with *real* experience.
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Old 07-24-2003, 01:13 PM
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FWIW, I came to the same conclusion, you allude to in your (well posted) question.

I was really liking the idea of the retractable spoiler, but opted for the very stylish early Carrera/Turbo tail. It was, after all, designed specifically for that body style.
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Old 07-24-2003, 02:20 PM
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Don't forget the cooling benefits of the 964 decklid. The 964 model may have had better body aero, but it lacked a rear engine-mounted cooler, and the ducktail moves a lot more air in there.
Old 07-24-2003, 04:54 PM
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Quote:
Originally posted by JackOlsen
and the ducktail moves a lot more air in there.
I agree with that. My Car runs much cooler in the Summer heat with my Ducktail vs. no tail.
Old 07-24-2003, 07:01 PM
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Cool

Quote:
Originally posted by widebody911

The C2 lid is marginally better than nothing.
dam it..

I don't need much.. but I need something..
I gotta keep the float down between 60-90mph, on big windy roads.. I was planning for that C2.. dam ...........Ron
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Old 07-24-2003, 08:00 PM
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dam Ron..LOL! ...I'll sell you my dam C2 lid

..I'll just increase the rake and put my AC compressor back in. Dam!
Old 07-24-2003, 09:42 PM
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Quote:
Originally posted by Souk
dam Ron..LOL! ...I'll sell you my dam C2 lid


hi Souk,
don't sell it to anyone else but me, i think.. I gotta hear from Thom on this, or anyone else.. if he says NG for my ride then I'll send you a sympathy card.. I always thought that C2 had to be good for something.. I hope Thom was just making a track statement.. but the good news is that I didn't screw up my rear window install today, I think .........Ron
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Old 07-24-2003, 11:43 PM
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Found the article...C&D September 1998, p.153.
The car used was a 1999 Carrera ( so not exactly C2, but similar).
First they tested drag...six high speed coast-downs at a test track in opposite directions..100 mph to 80 mph in neutral. In both cases of spoiler up or down...exactly the same 1.89 feet per second per second decel rate. No difference.
Next..Top speed test. Spoiler down 164 mph. Spoiler up 165 ph. Hardly a difference in speed. However, they did say the car felt floaty with the spoiler down and more planted with it up. BUT..."down" at 145 mph, the car steered and felt exactly the same. No effect.
So...IMHO...it was more a marketing move than an Engineering one by Porsche , and also ( for C2) enabled low speed noise tests to be passed easily...because with the spoiler up, it increased the opening size for easier cooling at higher speeds. All in all, IMO...not worth the effort to retrofit to older cars.
--Wil Ferch
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Old 07-25-2003, 06:13 AM
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