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I was at a local porsche dealer the other day to grab the latest Nord Stern newsletter and a salesman pulled me aside to tell me that my car is very unsafe with its current configuration. He explained that the rear spoiler with the absense of a front spoiler will cause the front to get very light at speeds over 90mph. For the record, he was pretty nice about the explanation. I doubt he expected me to trade it in for a different car right then and there.

Anyway, I agree in principle that he may be correct. But am I the only one with this type of set-up?

And is he right? I plan to do some driver training at BIR next month, so I'm concerned about the set-up.

I figure i have the following options:

  1. leave as is and throw some sand in the baggage compt
  2. pull the rear wing off
  3. add a different front end with spoiler
  4. install wheelie bars

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post-18387-1179155157_thumb.jpg

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I could see what the guy at the dealer is trying to say. You can lose traction in the front wheels if there is enough lift but when hitting turns you will have to hit the brakes so the momentum will hit the front wheels. Personally I would get new coil overs or springs to lower the ride height. The front should be .5" lower. There are front spoilers out there but I do not think it is as necessary as the suspension change.

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I think the aero kit installation instructions mention this problem. The customer can install the side skirts alone, but if they go for the rear spoiler they have to install the front aero bumper as well. Porsche will not install the rear spoiler alone.

I would talk to a porsche dealer about alternative ways to fix this problem (install aero bumber, perhaps just the splitters, or remove the rear spoiler).

Edited by mpikounis
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front spoiler/splitter with no rear wing = OK

rear wing with no front spoiler/splitter = not OK

The dealer's right.

I'm curious to know on what basis such statements are made?

For earlier model 911's (ex. SC, Carrera, 964) it is definitely true that from a stability standpoint, if a rear spoiler is installed, the front spoiler must also be installed.

However, that logic doesn't really apply here.

The aerodynamics of the 996 are significantly different than earlier model 911's. As we all know, modern 911's, going back to the 964, use a retractable spoiler that deploys at a given speed to aid with stability at higher speeds. But when the rear spoiler of a 996 is deployed, a front spoiler or "splitter" doesn't also appear. This being the case, and if we apply the logic listed above, the car should be unstable, right? But it's not (it's actually more stable). In addition, other electronic aids for stabilization (ex. PSM) have been developed (although it's not likely to play a factor in this particular case). So, what may be true for earlier models may not hold true for later models. That said, the point is moot because...

This car has a complete Strosek body kit - front bumper cover, side skirts, rear spoiler and diffuser. Strosek, like the other major Porsche tuners - Ruf, Gembella, and Techart, performs wind tunnel tests on their designs and their product results certainly show that Porsche's "40+ years" of development can still be improved upon. Strosek has been around a long time. If, in reference to this front skirt, Strosek's website says that it "reduces lift on the front axle" (and it does say this: www.strosek.de), I'm inclined to give them the benefit of doubt - much more than some salesman who doesn't even recognize the fact that a completely redesigned bumper cover plays a factor in the equation.

Bottom line, I don't have a definitive answer but, unless someone backs up their statements with actual evidence to the contrary, I'm more than inclined to think the car is just fine. I certainly wouldn't go so far as to call it "very unsafe".

E-mail Strosek at the site I listed above and see what they have to say. That's the best answer - as opposed to a bunch of wild speculation and hearsay.

Edited by J-rad
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I agree with J-rad that an email to Strosek will probably clear things up. I think what people are saying here (including me) is that front and rear aero kit components have to be installed as a set. This applies to Porsche aero-kit rear spoiler and front bumper only. If Strosek have developed their own set perhaps it is just fine to leave it as is.

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I can't comment on the Strosek spoiler, but as far as the Porsche spoilers go, it depends on which spoiler you are talking about. These were taken from TSB's:

"Carrera" Rear Spoiler:

The rear spoiler has been developed, tested and approved for the following combinations:

Carrera rear spoiler with standard front spoiler;

Carrera rear spoiler with standard front spoiler and side member trim of the aerokit Cup;

Carrera rear spoiler with front spoiler (without lip) of the aerokit Cup;

Carrera rear spoiler with front spoiler (without lip) and side member trim of the aerokit Cup.

Other combinations are not permissible!

Aerokit "Cup II":

Authorized retrofitting options:

1. Front spoiler with spoiler lip only in conjunction with rear spoiler.

2. Front spoiler with spoiler lip only in conjunction with rear spoiler and both side member panels.

3. Only side member panels.

Other retrofiitting options are not permissible!

I think that is where some of the confusion lies.

Edited by Richard Hamilton
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I also have a Strosek rear spoiler just like yours, except that my spoiler is only the main lower section, not the full two-layer spoiler that you have. I purchased mine through Fred Opert Racing in New Jersey, an authorized dealer for Strosek parts. They told me that I could install the main spoiler body without modifying the front end, but not the additional second level like you have. I have installed the rear main Strosek spoiler and I can confirm that even with the single-level wing, the front end did get a little lighter.

For part of my drive to work every day for the last six years, I had a fairly straight section of highway that is pretty much impossible for police to patrol, it is two lanes each way with a concrete divider and guardrails, and downhill when on your way to town. I typically reached between 80mph to 110mph most days on this stretch depending on the amount of traffic. At 110mph, the front end is uncomfortably light, almost spongy/springy. My personal max speed in this car is 145mph, but that was on a section with no turns. Again, it was not comfortable, I knew the car was technically capable of more but did not want to try it. Prior to installing the wing I did not feel this level of discomfort at high speeds. I had our Boxster up to 140mph and felt like I was fairly stable compared to the 911.

I also tracked this car (with just the Strosek rear wing) this year at Laguna-Seca, but the top was down the entire day and I never reached more than 110mph on the main stretch so aero wasn't too much of a factor for me there. The balance of the car felt very good even at reasonably high speeds through the corners in turns 4-7. My 996 is not lowered, I have the factory springs, but you can see that it drops pretty low through the corners anyway.

I definitely think it's not as safe in this configuration, but it looks a lot cooler (subjective, I'm sure), and I haven't been so worried about the imbalance that I felt compelled enough to spend money to change the front end. However, since you have the second level of this spoiler your car probably experiences more downforce than mine.

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I also tracked this car (with just the Strosek rear wing) this year at Laguna-Seca, but the top was down the entire day...

Interesting. Did you do this event with PCA? That would never fly in our region. If you have a cabrio/roadster the top must be up the entire time. Hardtop is preferred if you have one. Driver's window must also be closed (can be open 1"). Passenger window can be open, provided there is no instructor in the car. It would be fun to drive the track with the top down.

For comparison sake, it's also interesting to note that, as you indicated, you do not have the Strosek front spoiler/bumper cover or side skirts.

Edited by J-rad
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I also tracked this car (with just the Strosek rear wing) this year at Laguna-Seca, but the top was down the entire day...

Interesting. Did you do this event with PCA? That would never fly in our region. If you have a cabrio/roadster the top must be up the entire time. Hardtop is preferred if you have one. Driver's window must also be closed (can be open 1"). Passenger window can be open, provided there is no instructor in the car. It would be fun to drive the track with the top down.

For comparison sake, it's also interesting to note that, as you indicated, you do not have the Strosek front spoiler/bumper cover or side skirts.

This was a PCA section-sponsored event done in conjunction with two driving schools in the region. I have a hardtop for the car, but they specifically stated that if you have a convertible, you must have a welded-in roll bar or factory pop-up bars (which all the 996 cabs have) and the top must be down. I thought it was unusual too, but I wasn't going to argue, it was a great experience with the top down. I see what you mean though - we should do everything possible to help keep people's limbs in the car. The glass is going to break with any significant impact and wouldn't be of any value rolled up (maybe even more of a danger), but I can see how the hardtop would be of some value. Even though it's light aluminum and the top will be crushed, I'd bet that the hardtop would still provide a significant extra level of safety from direct helmet impact or getting pulled around from sliding. I don't see any value in having a soft-top up. A rollover would tear it apart and introduce various broken pieces of the softtop frame around the driver and instructor. They have numerous events every year and said that only one car has rolled in over 25 years, and it was an older Nissan passenger car with bald tires.

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I am surprised they ask you to keep the window up. All PCA and other clubs in the South East (NASA, Mazda, BMW, private schools) that I have been to ask for both windows down. Always for safety. The top (open or closed) is more track dependent regardless of club or event holder, Road Atlanta is top down always, Carolina Motorsports Park is top up, Roebling Road top down, VIR can't make up their mind and depends on who you ride with. That is for 996/7 and Boxters, otherwise you need a rollbar.

So I bought a coupe.

I did hit a tire wall once at CMP, and if my passenger window was up the glass would have landed on me. This is me at VIR, the slow pokes behind me are Ferraris

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I am surprised they ask you to keep the window up. All PCA and other clubs in the South East (NASA, Mazda, BMW, private schools) that I have been to ask for both windows down.

Yes, I've heard the arguments in support of this (and they made sense) but that was the rule. Notice I said was. I haven't been to a DE yet this year but am looking at going to one in about 2 weeks. As such, this morning I looked over the rules for this year (they were published at the end of April). Good news - it looks like we are now in line with other regions as far as the windows are concerned. That is to say, all windows must be down (removable window nets are encouraged). This is a new and welcome (from my perspective) change. Tops still must be up though (not a bad rule, IMO).

Edited by J-rad
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You people are gullable. It's so cute.

Let's see, the car weighs over 3000lbs. And say about 1000 lbs of that is on the front wheels. Then you go 100mph and you generate 100lbs of upforce.

Hmmm... So there's only a mere 900lbs pushing the front of the car into the ground. So now you can see how your Porsche has a better glide ratio than a bird!

:renntech:

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I would have to ask are you racing your car. You could do 1/4miles all day long with that setup with no issues. But if you are hitting curves above (Cannot be exact)90-100mph then you could run into a problem. On a normal no spoiler car you can lose grip fairly easily while high speed manuvering but when you have an active tuned spoiler on the rear it will apply force to the rear of the car, and with that actually lessen the force on the front of the car. (Less you have a 930 slant :notworthy: ) In all if you are out there sporting your car out like your racing everyone, then you do need to upgrade your front end. Front spoilers (lips) do one really big thing they restrict the air that can get under the front in turn making resistance and downforce. If you are just enjoying your car and topping out around 80 or so then you will be fine.(all statements are based on applied physics, and do not apply on dirt, gravel, in tornados, or hurricanes, in the event of a flood you will be fine)

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