The RS4 Sedan Project

Article by: Jason Teller & Photos By: Nikolaos Seizis

Unlike the RS 6 which would come after it, most people know that the RS4 was never produced as a sedan from the factory. This, of course, has done little to slow down enthusiasts yearning to convert their B5 S4 sedans into something worthy of wearing Audi’s coveted RS badges. Many have bolted on everything from RS4-style wheels to intercoolers, turbos or entire body conversions.

As with any enthusiast project, however, results vary widely. One tuning shop’s positive results have just as easily been another shop’s nightmare project. Experience, patience, money and a bit of serendipity must come together to produce something that actually looks and feels – from top to bottom and inside and out – like the real thing.

One such enthusiast, having fallen in love with the Audi S4 biturbo, initially thought of it as “a nice family car, not noticeable at all but with lots of potential.” Like many people at that time, Nikolaos Seizis began a search which started innocently; he simply wanted to learn as much as possible about the Audi S4 through car magazines and the internet. His S4 education quickly led him to the conclusion that it would be possible to build an unbelievably unique RS4 sedan – something that would truly be at the pinnacle of S4 modification.

By March 2000 it was time to order the car. With approximately 3 months lead time for a Nogaro S4 sedan with the blue insert alcantara interior, there was even more time to plan the upgrade strategy. In mid-May 2000 the car was finally delivered and ready to begin its journey.

Nikolaos was diligent in researching European tuners, including MTM, Abt, Sportec, Hartmann Motorsport, Oettinger, Digi Tech, Projektzwo and many others before eventually selecting MTM to handle performance tuning for his S4. This decision was primarily a result of MTM owner Roland Mayer’s experience as a former Audi AG employee and in particular with Audi’s turbo engines. Reliability was a key concern and it was felt that MTM had the right mix of not-over-the-top output increases and experience with the fundamentals of Audi’s turbos. Nikolaos also noted MTM’s tight cooperation with Audi AG and quattro GmbH, including testing together at the track. The downside: MTM was far and away the most expensive solution.

The very same day the car was delivered in Ingolstadt it was on to MTM’s shop, three minutes away in nearby Wettstetten. The initial improvements were an upgraded ECU and cat-back exhaust boosting output to the low 300’s, typical modifications for B5 S4 owners the world around. The extent of the tuning over the next 4 years would be anything but typical, however. Nikolaos practically became a fixture at MTM’s shop with every mechanic and other member of the MTM team well acquainted with his project car.

Piece-by-piece over time the S4’s engine would eventually be replaced with OEM RS4 parts intermixed with MTM parts. Final horsepower for the project car would be in the 470hp range. In order for the engine modifications, and specifically the ECU, to work correctly with the speedometer and tachometer the car actually went to Audi AG for final tuning. After two days of highly specialized work the car was eventually fitted with a special S4 / RS4 / MTM motronic box. MTM’s connections at Audi proved invaluable to completing this part of the project.

With so much power available to the car it became as much a question of safety as of performance, and the braking system was therefore tackled head-on. Mov´it was eventually selected over competing products from AP-Racing, Tarox, Brembo and Alcon. Nikolaos would be the first to admit that the evaluation process was two parts technical and one part gut-feel, but he put Mov´it ahead of the others based on both their design and their performance.

Mov´it uses a very efficient cooling system for its 342x34mm front rotors (similar to Porsche) utilizing Mov´it 6-piston monoblock calipers. The rear brakes are 322x28mm in a 4-piston design, and there is a separate Brembo hand brake. The result is a braking system with ferocious stopping capabilities and absolutely no fading, even during repeated track-speed stops. Final installation and adjustment was performed in Mov´it’s shop in Achern, Germany by Guido Frenssemeyer, Mov´it’s founder and the person most responsible for development of its brakes.

For as many things as Audi got right on the B5 S4, the suspension is frequently identified as a weak spot. Designed, perhaps, as too much of a hybrid between high performance and high comfort, it ends up doing both of these things in an ambivalent manner. Unsurprisingly, Nikolaos recognized the suspension upgrades in his RS4 sedan project car as the most satisfying from both a performance improvement and a bang-for-the-buck perspective.

Collaborating once again directly with the manufacturer, Nikolaos provided critical particulars such as weight and weight distribution, horsepower, torque, braking system, wheel dimensions and weight, tires, spacers and his own personal expectations of suspension characteristics. H&R in turn used the data to produce a height adjustable sport suspension, including the H&R Power Control System providing compression and decompression adjustability. In fact, the suspension for this project car was prepared in the same special department at H&R that does suspension work for DTM.

Together with a stiffer rear roll bar from quattro GmbH, the H&R suspension completely eliminates the pronounced nose-diving seen in stock B5 S4’s while improving the firmness of the ride dramatically. While the suspension setup is clearly capable of supporting high performance driving (the track), it must also be noted that it yields a relatively comfortable ride on smooth (highway) roads. It just gets stiffer when driven aggressively.

To cap off the custom suspension, the bumpers the shock absorbers have gold stamps proclaiming “Setup for RS4 Sedan Project”.

Moving on to wheels and tires, Nikolaos maintains three sets of BBS’s – the natural choice for the project from both a performance and design perspective. Everyday driving sees the car sporting BBS RXII 2-piece wheels sized 8.5 x 18 offset 32 and shod with Pirelli PZero Rosso 255/35 ZR18 rubber. On the track it’s one of two choices, either BBS CH 8.5 x 18 offset 35 which are nearly 3 pounds lighter than the RXII’s or for the most important track days BBS RC 8.5 x 18 offset 35 which are the lightest BBS makes at a mere 20.7 pounds each. For the track wheels in each case they include Pirelli PZero Corsa tires at 255/35 ZR18.

Up to this point the modification and additions to the car, albeit custom work in many cases, were generally “bolt on”. No major mechanical or body modifications were made until it was time to tackle the RS4 bodywork – one of the most complicated and demanding parts of the project.

Bodywork conversion was handled by I.S.R. in Prague, the leading Audi dealer in the Czech Republic. Meticulously using only OEM RS4 parts, the entire job took exactly three months from start to finish. The credibility regarding the quality of the work came later on when people from MTM, Audi AG and quattro GmbH saw the car, universally declaring a conversion done perfectly.

The best anecdote around the bodywork was a trip Nikolaos made to Neckarsulm to visit Stephan Reil, the head of development at quattro GmbH. Parking the car in front of the main entrance, quattro GmbH and Audi employees soon gathered around the vehicle. They erroneously believed that Audi had actually produced a secret factory RS4 sedan. The work was just that good.

The S4 is quite a heavy car and the decision was eventually made to reduce weight, particularly in the front. In all about 220 lbs were removed from the vehicle, with over 100 lbs of that coming from the front. Some weight was also transferred front to back; for example the battery was moved to the trunk. The resulting weight savings not only boosted performance, but also helped to balance weight in order to optimize the interrelated suspension, brake, wheel and tire systems.

The goal for this project car was to create something highly individual while extremely performance oriented. Nikolaos wanted the fastest street legal 4-door Audi in the world and created something that could no doubt easily compete for the honor. He’s got a 0-100km/h time of 4.1 seconds to back it up, too.

Nikolaos was invited by quattro GmbH to participate in the RS Challenge 2003 event at Hockenheim – an event attended by 60 other RS4 and RS6 owners from across Europe. The majority of the cars were RS4’s and amazingly, according to Nikolaos, there was not a stock one in the group. Project RS4 sedan produced the 4th fastest lap overall despite the fact it was Nikolaos’ first time ever driving at Hockenheim. At a more recent track event up against he likes of the Porsche Turbo Techart 550PS, Pagani Zonda, 911 Gemballa, Murcielago, 360 Modena, various M3’s, RS4’s and S4’s, the Project RS4 sedan had the second fastest time behind only the Porsche Turbo. This is of course as much a testimony to driver skill as to the performance of the vehicle, although Nikolaos contends he is driving an unparalleled automobile.

It surely must also be noted that while Project RS4 sedan is in the performance league of the rarest of automobiles, it still retains it sedan qualities. Five people can ride in the car and it can perform as well at the track as it can in snow on the way to the ski hills.

Project RS4 sedan has been featured in various magazines in the Czech Republic, including Autocar, Speed, Autosport & tuning, Auto forum, Auto special and others. It has also been presented on TV, making Nikolaos something of a celebrity among sports car enthusiasts in the Czech Republic. He is quick to point out that the various partners involved in the project deserve a good deal of credit; without them the car just wouldn’t have been possible.