A gallery of tuned A4s from the pages of european car
MTM Audi A4 GT 286 hp
Of the half dozen or so modified A4 1.8T models tested so far, the one that goes straight to the head-of-the-class comes from MTM (Motoren-Technik-Mayer) which is based in Wettstetten, just 10 minutes drive from Audi's Ingolstadt factory.
With 286 hp at 5800 rpm, and 228 lb-ft of torque at 2480 rpm, the 1,340kg Audi has a power/weight ratio of 4.2 hp/kg and superb traction off the line. This gives it rocket-like launching abilities, reflected in its 5.1-sec 0-to-60-mph time, which betters even the Euro-spec 321- hp 3.2-liter BMW M3 Evolution by 0.3 sec! On top speed the A4 GT, as Roland Mayer has designated his car, will claw its way to a genuine 265 km/h or 166 mph; quite fast for a compact four-door sedan actually and a match for a Porsche 911 Carrera!
Everything after the exhaust ports on the head is changed. A new manifold, which takes its basic design principles from the Audi Sport IMSA cars, is mated to a larger KKK K24 turbo from the Audi S2. This particular turbocharger is the right size for the engine and required power output, but was also chosen because it does not have an integral wastegate. The stainless-steel exhaust system is made for MTM by Piper in England, and Mayer is very complementary about its work. Incorporated in this is a free-flowing metal catalyst. Other modifications are a free-flow air filter and a larger capacity intercooler fed though the big intake in the new deep-front spoiler. Normal MTM A4 GTs for customers cars with 286 hp retain the stock intercooler, but this particular car was undergoing durability testing for the 300-hp Stage 4 conversion, hence the larger intercooler.
Bigger injectors supply the extra fuel required by the uprated engine. These are new Bosch designs with four smaller nozzles in each normal-sized injector unit providing a more accurate spray. This helps both fuel economy and emissions, and means, in effect, the MTM Audi ends up with 16 injectors! The camshaft is not changed as it works fine and any more overlap would eat into the relatively clean emissions.
The ECU has been modified to work with the new fuel, ignition and boost parameters which is fairly straightforward for MTM's electronics boffins. The pressure control system is different, however, and the new Motronic system controls airflow rather than boost. This means when the inlet air temperature goes up, the boost pressure is altered to maintain the power level, i.e., when it is hot, boost pressure is raised and vice versa independent of ambient air temperature.
The A4 1.8T sits 20mm lower than its naturally aspirated brothers, but the MTM sports suspension is twice as low, using MTM's own springs and bespoke Konis. The 8.5Jx17-in. MTM alloy wheels with 245/40ZR17 rubber now sit perfectly in the center of the Audi's round wheel arches when you look at the car from the side--no modifications to the metalwork being necessary.
The interior of the MTM demonstrator has been given just as much thought as the engine. Open a door and you instantly catch a whiff of quality leather. The Recaro seats, standard rear seat and the door panels have been beautifully trimmed in black and blue leather. Where you would expect to find wood on the dashboard strip and door panels on a luxury car or carbon Kevlar on a sports version, the MTM car uses an aluminum-look finish.
Roland Mayer is adamant that 300 hp is the sensible limit for a road car which does not compromise durability. He is also quick to admit the Stage 4 conversion may not be the end of the story. "Racing versions of this engine have been getting 450 hp from four cylinders, and four valves per cylinder so there is no reason why we should not be able to crack 400 hp from this five-valve engine," he said. "At the end of the day, it is down to whether or not this new cylinder head is strong enough. We are testing!"