Hansen Motorsport S4 Oozes RennSport Philosophy

The RS that Never Was

When you’re the man behind an automotive performance company, as Øystein Hansen is, you’re bound to have a pretty spectacular commuter car. Known for creating 722 hp long-wheelbase Ur-quattros weighing in at only 1130kg, or turning S90s into IMSA GTO tribute cars, Norway’s Hansen Motorsport (not to be confused with Sweden’s (Kenneth) Hansen Motorsport—Peugeot’s rallycross partner) also acts as a laboratory for Hansen’s daily driver dreams. The car in question here is his 2000 Audi B5 RS 4 sedan. The obvious question is where did he get a four-door B5 RS 4, since that series RS 4 originally only came in five-door flavors. The inevitable answer is: he built it himself.

More than a Swap

While it would be easy enough to simply switch over the sedan’s existing twin-turbo 2.7-liter V6 to 375 hp RS 4 Avant specification, Hansen embraced the spirit of Audi’s RennSport mindset and tacked on an extra hundred hoses or so. To accomplish this, he focused on boost. From his experience tuning Audi’s V6s, he knew the engine’s internal were up to the task of churning out all that extra power, so only a camshaft replacement, with factory RS 4 cams, was needed. 

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Turbos

While the stock long-block was all set to go, the original turbos got the axe. A LOBA Motorsport turbo kit was pressed into service to get things rolling in the right direction. Their LO600P kit utilizes highly-modified dual BorgWarner KO4 RS6 turbos. The turbos inlet housings have been machined to accept larger compressor turbines, and the housings themselves have been modified for improved flow. Hansen bolted the BorgWarner turbos to facelift-model S4 exhaust manifolds and fabricated a custom exhaust system for his RS 4 four-door. 

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Engine Support

The turbos work with the stock RS 4 intercooler and intake manifold, though most of the fuel system has been updated. A Bosch Motorsport 044 fuel pump was added and feeds a RS 4 fuel rail, controlled by a RS 4 regulator. Siemens DEKA IV 630cc injectors provide the fuel charge, and ignition comes from 2.0TFSI ignition coils, as controlled by a Hansen Motorsport re-mapped Audi S4/Bosch Motronic engine management system.

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Carbon

Underhood, the carbon fiber engine shroud conceals much of Hansen’s magic, but on the outside, paint hides much of the sedan’s carbon fiber. The carbon front fenders have been subtly tweaked for width, ditto for the factory RS4 doors and modified rear fenders. Hansen reworked the RS 4 front bumper, adding Seat Cupra R lip to its shape. The Audi’s side skirts were adjusted to make them deeper than usual, in turn making the car appear lower than it actually is, and the RS 4 Avant rear bumper was adapted to fit the sedan’s contours.  

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Suspension and Braking

Other Carbon bits include custom-made WRC-type mirrors and an understated trunk lid spoiler. The 18×9.5-inch Zito ZL111 alloy wheels Hansen chose to fill the newly-widened fenders skillfully walk the line between aggression and restraint. To keep handling up to par with the engine’s increased output, Hansen fit H&R coilovers and stiffer front and rear sway bars, while braking was brought up to snuff with the addition of Porsche GT2 6-piston calipers clamping Brembo 365mm rotors up front.  

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Inside Again

Inside the Audi, the factory’s ergonomic science has been left mostly untouched, though Recaro Pole Position racing seats now reside in place of the stock units—a change clearly called for because the car sees track days on the regular. The rear seats are also a casualty of the car’s competitive nature, they’ve been sacrificed to make room for a bespoke partial roll cage. At first blush, a roll cage in a street car might seem counterintuitive, but when you daily drive a 550 hp B5 you need something to tie the groceries down to. 

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