Q&A Porsche discussion

[st-anger]

Originally Posted by mrmojo77 How many factories does Porsche have and what models are manufactured where? I'm curious, because I know Valmet is making Boxsters in Uusikaupunki, but do they make Boxsters also somewhere else and where are the other models made?

…“made in germany is our sales argument“ is what you hear when someone asks this question, especially for the US market this is probably the main point when buying a Porsche, approx. 90% of the parts are made in germany, the percentage of handwork is way above the average in automotive industry, and what they ( US, Asian, Arabic, … customers ) especially like is the addition: “tested on german autobahn…”

so, basically the 911 modells as well as all the engines including V8 from 955´s are made in Zuffenhausen, near Stuttgart, the engines for the Cayenne are then transported to Leipzig, located in east germany, where the Cayenne is assembled as well as the Carrera GT…
also the 4th model will be produced there when the CGT line will be free ~2006, 2007…

due to the high demand for Boxster models and the fact that the Zuffenhausen plant had been running at 100%, PAG outsourced the Boxster production in 1997 to Valmet Automotive in Uusikaupunki, Finland. again the engine and subassemblies are comming from Zuffenhausen, other main parts from suppliers from germany, Valmet is responsible for assembling, bodyshell work, painting and finish…

there´re also some other enterprises like PES and PEG, based in Bietigheim (germany), Troy (USA) and Prague (Czech Republic) all controlled by EZW, with a overall capacity of over 1000 engineers inside whole PEG…

Porsche engineering

Porsche in Zuffenhausen

Porsche Leipzig

[st-anger]

Originally Posted by mrmojo77 Thank you for the info. I'm happy to see that this China phenomenon has not stepped in the automotive area, like it has done in so many other ares.

...i´m afraid i´ve to dissapoint you on that, countries like china are nowadays on top of every manufacturer´s list, the economic growth in regions like china is simply too tantalisingly...
i´m not that familiar with the details, but i know all the big german manufacturers have them on their watch list...

[possessed_beaver]

Originally Posted by st-anger Originally Posted by mindgam3 great picture of that M3 st anger love it ...have some more pics like that one, hopefully there´ll soon be a own NS topic in "PC" so keep an eye open... here´s a another one ///M5

i use to have that as my wallpaper, i got that off the nurunburg (spelling) website, but i havent seen one without the watermark on it

[DJF1]

Regarding the ABS issue I just wanted to offer one little detail here... While on racing/track situations the ABS is really good as it keeps the car more or less stable and most importantly does not upset the given weight transfer load. It is true 911's need another type of driving, for the average driver a slow in fast out approach works best for sure, having said that it is possible to trailbrake a 911 especially using left foot braking and throttle at the same time. I use that technik often on slow corners to reduce the inherent understeer which is amplified by my Porsche Motorsports LSD, but have not developed the balls so to speak to use that on fast swepers yet It is for sure a different beast, when your brain says lift you have to add throttle and such bizarre things! Back to the ABS though, the ONLY time you will benefit from a non ABS braking system is when you spin! Ideally you want to lock the brakes there to minimize a dangerous phenomenon which is coming back ON the track.. Let me explain... When you loose the car ( especially on snap oversteer) you want to put "both feet in" , in other words brake and clutch. A lot of cars after spinning will go to one side and then start sliding back on the track. That is very dangerous as if you follows they can side hit you ( trust me I have been close to one) . Cars with ABS due to non locking have more tendency to do that if that makes sence to all where without ABS by locking the brakes your trajectory is more defined and the chances of coming back on track are less...

[lakatu]

Originally Posted by DJF1 Regarding the ABS issue I just wanted to offer one little detail here... While on racing/track situations the ABS is really good as it keeps the car more or less stable and most importantly does not upset the given weight transfer load. It is true 911's need another type of driving, for the average driver a slow in fast out approach works best for sure, having said that it is possible to trailbrake a 911 especially using left foot braking and throttle at the same time. I use that technik often on slow corners to reduce the inherent understeer which is amplified by my Porsche Motorsports LSD, but have not developed the balls so to speak to use that on fast swepers yet It is for sure a different beast, when your brain says lift you have to add throttle and such bizarre things! Back to the ABS though, the ONLY time you will benefit from a non ABS braking system is when you spin! Ideally you want to lock the brakes there to minimize a dangerous phenomenon which is coming back ON the track.. Let me explain... When you loose the car ( especially on snap oversteer) you want to put "both feet in" , in other words brake and clutch. A lot of cars after spinning will go to one side and then start sliding back on the track. That is very dangerous as if you follows they can side hit you ( trust me I have been close to one) . Cars with ABS due to non locking have more tendency to do that if that makes sence to all where without ABS by locking the brakes your trajectory is more defined and the chances of coming back on track are less...

Great contribution. DJF1 it is nice to see you posting more frequently again . I always especially enjoy hearing from people who have track experience in a 911. Interesting technique to apply the brake and throttle together to reduce understeer. I am guessing the way it work is it causes the back wheels to rotate faster than the front.

[ae86_16v]

St-Anger: I remember reading somewhere saying that you didn't really like the 986 Boxster S. And I was wondering why?

Other members feel free to contribute.

Also how much more money could I expect to spend on maintenance over an E36 M3?

[st-anger]

Originally Posted by ae86_16v St-Anger: I remember reading somewhere saying that you didn't really like the 986 Boxster S. And I was wondering why? Other members feel free to contribute. Also how much more money could I expect to spend on maintenance over an E36 M3?

don´t get me wrong, the Boxster IS a nice car, and in it´s class definitely among the best when it comes down to pure performance, and this´ll get even better with the new 987series - there´ll be some nice suurprises inside 987 model range , as i said some days before, the Boxster is also very very important for PAG as it´s a draught horse for business, BUT...till now i couldn´t familiarize with the Boxster as a Porsche, it´s always afflicted with "poor man´s Porsche" - don´t get me wrong with that said, but personally, before buying a Boxster - just to have a Porsche - i´d buy a e.g. Z4 or whatever, regardless which age...
for me the Porsche world starts with a 911...
so how much more...hmmmm, to be honest can´t really comment on that in detail, but as u know....it´s a Porsche and everywhere where´s a Porsche badge on it....it´ll be a bit more expensive.....
but no problem, just go to your local Porsche dealer - they´ll be able to tell you everything

[lakatu]

Does anyone know if Porsche uses venturi duct aerodynamics to reduce rear end lift on either the 996 or 997? This technology is used on the Ferrari 360 CS, Ford GT and Carrera GT but I don’t believe that the technology is used on the 911 yet. If not venturi ducts, then is their any other undercarriage aerodynamic effects used on the 911? Assuming that the venturi technology isn’t used, is the rear engine design incompatible with venturi aerodynamics?

I have wondered for years why the Porsche didn’t eliminate the pop up air spoiler and incorporate the spoiler underneath the car or at least supplement the pop up spoiler with an aerodynamic device underneath as well. The only undercarriage aerodynamics that I can recall on any Porsche other than the Carrera GT is the 944 turbo underbody spoiler. Does anyone have any possible explanations or information concerning these issue?

[nthfinity]

with cars like the CS, and Ford GT, a rear wing would affect the asethetic flow of the car greatly. further, it would not reduce drag, so other means of getting the applied forces were persued.
i made a shitty diagram to help...

one can reduce lift on a car by creating 'ground effect' which is induced by the front air splitter reducing the volume, and therefor, velocity of air under the chassis. this vacuume literally pulls the car down. to increase this effect, the underside is made flat.

the air that passes through the front also has some ducting to cool the front brakes, and an efficiant pass-through design to cool the radiator efficiantly causing less drag.

as the air passes towared the rear of the car, the venturis direct the air by causing them to vortex. this gets a larger mass of air to move predictably. as directed, the air fills in the vacuume behind the car, and literally forces the air up, and pulling the car down.

as air passes over the car, there is a high pressure zone on the windscreen, and allows less air to pass over the rear of the car, but rather deflected. the air that idoes pass over the roofline, is drawn down across the rear window, to the duck tail and then forced up before receding back to the vacuume.

ive only seen a carrera 4 997, so im unsure of the higher models; but the c4 doesnt appear to have any under side areo. the long tail design would produce less of a vacuume that the CS, or GT would, and underside areo wouldnt benefit the car much. im sure, however, that much thought went into designing the front air splitter for great ground effect to pull the front tires to the pavement.

with a retractable tail, or otherwise, drag is increased to stabalize the car at higher velocities by reducing the lift. without a ductailed spoiler on that lid, im unsure if any d/f is increased over the rear. im sure Stutgart doesnt want to have any flying porsches

if the underside of a 911 were flattened to increase ground effect, then perhaps the engine would be much more dificult to access, being that porsche boxer 6's really are quite cramped in the bootlid.

with the CGT, the rear spoiler raises at speed to create extra d/f by elevating itself from the vacuume behind the car, and reducing its tendency to revert back to it so quickly, im sure it would almost negate its effect.

im sure porshe has quite a few reasons why they havent used ground effect much yet in their production vehicles...

[zmydust823]

porsche =number 1...nuff said...dont need to go into detail lol

[lakatu]

Thanks nthfinity for providing some information about aerodynamics. I can tell that you are knowledgeable concerning automotive aerodynamics. Since I last asked the question I have been reading to try and understand the concepts better. Maybe you can provide some critic and see if understand the venturi tunnel concepts.

Lately I have been really interested in aerodynamic down force as an aid to increasing cornering speeds. It started when I learned that the main difference between prototype classes and others based on street cars is their aerodynamic down force which allows them to corner much faster. As a result, I have noticed that many of the newer car designs incorporate the venturi tunnel as a way to increase down force.

From what little I understand about the subject it sounds like it is based on principles similar to those used to create lift on airplane wings. Many of you are most likely familiar with these principles but for those that aren’t the way an airplane creates lift is through a relative air pressure imbalance between the low pressure on top and higher pressure on the under portion of the wing. This results due to the shape of the wing which flat on the bottom and curved on top.



The curvatures on top is longer than the flat under portion. As a result the top portion of air has to travel faster than the lower portion since the distance is greater. This higher velocity of air on the top is associated with lower pressure due to some physics that I can’t explain here.

The ventrui tunnels used on CGT, Ford GT and Ferrari’s 360 CS uses the same principles. St-anger provided some incredible pictures of the CGT to help me demonstrate these aerodynamic features. The first picture is the bottom view of the underneath side of the CGT. This is the undertray and I labeled the front portion and the area of the rear diffuser. The rest of the pictures are a view of the undertray attached to the CGT from behind and again shows the rear diffuser. It is the rear diffuser that acts like the curved portion of the airplane.



As air flows underneath the car, as it comes upon the rear diffuser where the cross section of the undertray increases and the distance the air has to travel also increases. To see this imagine taking the undertray off and pounding it flat, although this isn’t possible because the undertray is made of carbon fiber and while strong isn’t malleable. The curvature of the undertray up towards the bumper is longer than if the undertray were flat and ran straight across to the bumper as normally would occur. Because the distance of the undertray increases the distance the air has to travel increases, the velocity of the air increase and the associated air pressure decreases. As a result, the air pressure above the car is greater than beneath the car and this creates a net downward pressure, increasing down force and lateral grip. Pretty ingenious. It is also sometimes referred to as an inverted wing.

IMO the 911 shape is one of the most beautiful in automotive design. I especially like the shape of the G-series or the 1974-89 shape, if you couldn’t tell from my earlier posts. Sadly these aerodynamic aides don’t appear to be compatible with 911’s as it appears to me that the placement of the engine low at the extreme rear of the car prevents creation of a rear diffuser. Additionally, the overall shape of the 911 resembles the shape of an airplane wing more than any other car. The end result is that the shape of the car creates lift especially over the rear axle at high speeds.

If you follow the changes that have been made to the design over the past 10 years you will notice that the rear portion of the car use to drop from the roof line to all the way to the bottom of the rear bumper. This long line relative to underneath the car meant air traveling over this section of the car was traveling at a higher velocity and therefore had less pressure associated with it, creating the lift over the rear axle.

Tea tray spoilers help by shortening the distance the air has to travel and therefore the speed, reducing the pressure differential and lift associated with it. Spoilers also created down force, so they accomplished two objective to decrease rear lift. The changes that have been made to the shape of the 911 have been to decrease the long drop off from the roofline to the bumper by raising the bumper line and to add popup spoilers to further shorten this line and create more down force.

So unfortunately the 911 not only has the challenges associated with the rear engine weight bias but a shape that creates lift at high speeds. The end result is that the 911 is even more prone to spin in high speed turns. But regardless of its faults there is something that evokes passion in the 911. Maybe it is its reputation and the challenge of driving it. Maybe it is the pure simplicity of its design. But what ever it is for the Porschephiles there is nothing else like it .

I know this post was a little technical so I hope that it was helpful and interesting. I really enjoy this type of stuff and hopefully there are others out there that enjoy it as well .

[Tomerville]

St-Anger, do you have any information and pictures of the 993 GT2? I know the road version was quite limited, and of course not imported to the states, but since Need For Speed: Porsche Unleashed (a computer game) came out, I have had an obsession with that car.

Also, why are there some 997 Carreras in magazines with the 993 style headlights, and some with more 996ish style? Both are circles rather than ovals, but some have a chrome ring around the headlight unit, and then a little extension that goes toward the trunk, where the foglights are on the 996 models. It seems like keeping that little extension was an earlier design or something because in the later magazines, they all have the strict 993 style.

[nthfinity]

which is induced by the front air splitter reducing the volume, and therefor, velocity of air under the chassis

i feel kinda stupid for saying this... i meant 'therefore, the velocity of the air under the chassis is accellerated (less volume, greater distance)

thanks for the pictures, as now it makes a bit more sence when looking more keenly at these pictures.

i must note that special things happen near the ground with air, inverted lift, and a normal air foil, so basic principals dont always apply.

1: at ground level, there is inherently more air pressure. with an aircraft, this causes it to seemingly glide effortlessly as it makes an approach vector.
with a car, this is almost negated, as the pressure difference is almost undetectable.

2: air can be almost entirely be re-routed, rather then having to flow both above, and below the car... although, i think there was a flying Mercedes that this didnt work so well with a while back

in any condition, obviously the leading edge takes the brunt force applied to it, and little more then drag is created at that cross section... lukily, bernuli was wrong. (imagine 2 air molecules are next to each other, and one hits one side of a leading edge, and the other follows the other path. bernulli suggested that both air molecules [imagine a ball rather then a wing] would meet each other on the back side fo the object as if undisturbed. ) sorry for rambling, i dont recall what my point was going to be... ops: mabey something relating to friction/thermal loads. there are always sacrifices

anyway, i must say im suprised there arent at least 2 more venturi wings in the tunnel, and the decaying angle makes more sence then an increasing angle for cirtain.

I especially like the shape of the G-series or the 1974-89 shape, if you couldn’t tell from my earlier posts

i 100% agree... well, mostly anyway.

[lakatu]

Thanks nthfinity for your comments . You make a really good point that air movement is restricted by the ground and that this generates complications to the simplistic physics principles.

I should also mention that this down force usually isn’t “free” it comes with the price of increased drag. In the case of the CGT I am not sure what the drag coefficient is but the car generates approximately 700 lbs. of down force verses 200-300 on a GT2 or GT3. To be honest I don't know if or how much the venturi tunnel "costs" the CGT in drag. Racing cars are able to generate several thousands of pounds of down force but the drag coefficients are around twice those of a modern sports car.

Originally Posted by nthfinity anyway, i must say im suprised there arent at least 2 more venturi wings in the tunnel, and the decaying angle makes more sence then an increasing angle for cirtain.

I was wondering if you might explain what you meant by this a little bit more. I think you might be referring to the second picture. I noticed that picture has two attachments inside the tunnel while all the other pictures exclude those. Is that what you are referring to as ventrui wings?

[nthfinity]

Is that what you are referring to as ventrui wings?

yes, although i may note them incorrectly.
it would make sence to have fewer... say... to reach the 200mph mark to reduce drag vs. the cost of controlled d/f.
what happens at these fins is basically this; the air accellerates along a side, following the path of least resistance (leading towared the outside of the car in this case) and begins to create a vortex of air behind the fin. the vortex created by the fin always travels from inside--->out. aerodynamicists would often have as much upswing of this vortex as possible before leaving the path of the car, which is why i would've expected a few more fins... i.e. more d/f.

i do have a question relating

I am not sure what the drag coefficient is but the car generates approximately 700 lbs. of down force verses 200-300 on a GT2 or GT3

the coefficient of drag, Cd is quite affected by the frontal area^2, so id imagine its possible that the CGT my have greater negetive effect from this... but not much different from the GT2, or GT3. i do have one question, do you know what speed those numbers are generated at? often mfr. claims are mentioned at both 100mph, and 160mph.