en bonus une petite vidéo :
http://www.youtube.com/watch?v=uxlmecFwI6g
Il parle de Nardo et elle tourne aussi la nuit ?????
Quelques infos plus techniques:
-vilo forgé course 86.4mm
-piston forgé alesage : 82.5mm
-culasse forgé decomprimée et retravaillé avec 25v
-tx de compression 7.0 ou 8.0
-turboboost : 3.0 bar
-modele turbo inconnu mais refroidissement eau + huile
-allegement de la voiture au maximum (vitrage et carroserie notamment) pour ateindre 1072 kg
-pipe admission sur mesure et agrandit
-collecteur d'échappement inox sur mesure avec conduit plus gros
La plus part des photos provient d'un "Audi Magazin" paru le 2 juin 1997
Et enfin un Article en anglais :
Rallyes never were very known or loved in the US. So, Audi couldn't use their Rallye successes which helped selling in Europe in this important export market. To demonstrate the superiority of the quattro drive, Audi had to do something else. They modified a German Audi 200 Exclusiv body and added a "5000 CS" badge. With this car Audi went to a genuine American area: speedways. The car was built according to NASCAR rules and let loose (NOT lose) on the USA's fastest speedway: Talladega.
With turbocharging, all-wheel-drive and numerous hardly visible but extreme modifications (all complying with NASCAR rules!), the 200 succeeded in impressing the US. In Talladega the 200 with its 650hp reached a lap average of 332km/h (nearly 207mph). Thus it broke the big barrier of 200mph. On the straightaways it reached over 350km/h (over 219mph). In 1985 this time would have been enough for the first row in the starting line up. After this world-record for an all-wheel-drive vehicle on a circuit, the Audi team went on a promotion tour through the USA.
It is really hard to see all the changes that were made to this 200. It starts with a solid aerodynamic improvement. Drag was reduced by avoiding edges and ommiting the rearview mirrors. The body was lowered 40mm (about 1.6 inches), resulting in a smaller frontal area and a lower center of gravity. Downforce is created by the already known spoiler board up front and a small spoiler on the trunk lid. Spoilers cause downforce but they result in a higher wind resistance. Thanks to the aerodynamic changes, the cd-value of 0.33 could be kept.
The body panels were partially replaced: front and rear bumpers are made of Kevlar, doors and hoods are aluminium and the windows, apart from the windscreen, are made of plastic. The result is an impressive weight of only 1072kg.
In the banked curves unbelievable forces lie on man and machine: The Audi gets pushed to the surface with 2,2g (2.2 times its weight) while it is dragged to the outer curve by 1,6g! These forces result in a very hich dynamic wheel load on the outer tires. With higher wheel loads you can transmit higher forces through the area of street/tire contact, but an equal distribution of wheel loads is desired, especially for the tires. (The function is degressiv: More load gets you better grip but even more need for grip. So lighter is better, simply spoken. Or an example: If the vehicle weight doubles at the same speed, the centrifugal force doubles, too. but the tires can only transmit less than double the force.) One way to solve the problem of load transfer is by stiffer springs on the outer tires and softer springs on the inner ones. The difference in their sping rate is up to 60N/mm. Thus the rolling effect can be lessened. In this process, the car leans over towards the outer side and the center of gravity gets lifted, resulting in a growing lever arm for the forces. That leads to a further lift of the inner tires (so, more unbalanced wheel loads...).
Even more important is the weight distribution. As much weight as possible should lie on the inner half of the car. So the static wheel load is unbalanced on purpose. By shifting weight to the inner side Audi tried to balnce the dynamic wheel loads. Oil- and fuel tank are placed on the left as is the battery. Even engine, gearbox, drive shaft and the diffs are mounted 50mm (nearly 2 inches). So new shafts had to be made and the whole underbody had to be adapted. Even the driver had to move: he now sits farther left and 200mm (about 16 inches) farther back, which lead to new padals and steering column. The result: 58% of the weight lie on the front axle and 53% on the inner wheels.
The tires are of a pretty normal size, but tires larger than those 10inchers would not have fitted. Michelin first feared that the tires would not stand the stress. But they tested them in their lab and ended the test run at 450km/h (280mph) caused by their fear -for their lab! So it was clear, that the tires would stand up to the test. "Narrow" tires also have the advantage of a lower wind resistance.
The engine only reached 7200rpm at 350km/h, while it could have gone up to 7700 rpm. If the track had to much narrow bends or the gear box was too "long", is unknown to me. The secret of the engine lies probably in its cylinder head. Not much was told about it, except that it derived from the standard 20V. It was rumoured that it had a valve angle of 47degrees instead of the 25 of the Sportquattro.
Attention!
Till now I wondered if this might be a hemispheric cylinder head, as these use similar valve angles. But Winrich Germann sent me some pages from the "Audi Magazin", issue 2, June 1997. Besides the presenting of new engines one could read the following: "Begonnen hat alles mit ein paar schnellen Runden in Talladega, Alabama: Man schrieb das Jahr 1986, das Auto war ein Audi 200 quattro und das Triebwerk ein 2,2-Liter-Fuenfzylinder-Turbomotor mit 25 Ventilen und eindrucksvollen 487 kW (625 PS). Man fuhr dort einige Runden mir einer durchschnittlichen Reisegeschwindigkeit von 332,88 km/h, und die wichtigste Erkenntnis diese hochbeschleunigten Tests war die ueberlegene Leistungsfaehigkeit der Fuenfventil-Technologie (abgesehen davon, dass man einen Geschwindigkeits-Weltrekord aufstellte)."
Once again, this time my translation:
"It all started with a few fast laps in Talladega, Alabama: We wrote the year 1986, the car was an Audi 200 quattro and the engine a 2.2-litre-fivecylinder-turbocharged engine with 25 valves and impressing 487 kW (625 PS). Some laps with an average travelling speed of 332.88 km/h [206.84 mph] and the most important perception of these highly accelerated tests was the superior capacity of the five-valve-technology (apart from setting a speed worldrecord)."
Wow! And this is simply written in a simple paragraph! The first five-valve engine by Audi: 5x5 valves!!
If you want to see more of this engine, look at the pics I have taken!
Below this sensational head, much is stock: The block was only adapted to a dry sump (necessary due to the centrifugal forces), and the crankshaft was stock. However the piston rods were made of titanium and the pistons were specifically made with extra cooling channels. Air intake and outlet were redesigned and the "feeding" was changed quite a bit, too. 2 (two) injection nozzles per cylinder supply unleaded fuel (catalytic converter!!) according to the boost pressure. The result are solid 650PS at 2bar of boost pressure, what was not the "last word" according to some Audi people.
Concluding, I must say that the achievements of the Audi crew are stunning. It is hard enough to make a car fly so fast around an oval track, but using so much stock material and principles makes it nearly unbelievable. If you have another opinion, just take look at NASCAR racers. Besides the obvious difference of a tube chassis there are other major changes from a real "stock" car.
It is a pitty that Audi never tried to improve its records. And an Audi team on a salt lake race would have been spectacular, huh??
