Tradition demands it – every two years, at the International Motor Show in Frankfurt, a very special vehicle is presented. 2003 is no exception, as AC Schnitzer V8 Topster Concept was released. Based on the BMW Z4 3.0i, no stone is left unturned in the development process. The most striking optical feature is the enclosed bodywork, now 13 cm wider, in orange and cream.
The life-giving organ which was developed in record time as a one-off special in close collaboration with the BMW works team Schnitzer Freilassing, is the upgraded performance version of the 4941 cc eight cylinder, four-valve engine from the BMW M5. In conjunction with our technology partner, the engineers have equipped the V8 Topster with special intake and exhaust camshafts. The cylinder heads have also been fine-machined, the compression raised to 11.5 : 1 and the control unit reprogrammed. To improve the exhaust gas flow, an environmentally-friendly special steel high performance exhaust system has been developed with twin chromed racing tailpipe trims in right and left combination.
In comparison with the M5, the power plant has had to be re-positioned in the engine bay of the Z4 basic vehicle and the entire oil circuit optimised, so it was necessary to modify the oil sump and oil pump. Finally, the air flow was improved. By means of new intake pipes and 2 air filter boxes, the entire intake tract could be optimised.
To match the power of the engine, the drive train and rear axle were also modified. The rear axle, with a gear ratio of 3.62 : 1, has a variable differential lock from 0 to 100 percent depending on the load. In addition the AC Schnitzer Short Shift is fitted.
Braking is provided by the AC Schnitzer high performance kit. It uses larger brake disks of 365 x 32 mm at the front and 328 x 20 mm at the rear in conjunction with special brake calipers.
In motorsport the correct handling is often decisive for a victory, and AC Schnizer’s development engineers place particularly great importance on optimum suspension settings. In the V8 Topster the driving dynamics are decisively improved by the special development of a nine-position adjustable AC Schnitzer racing suspension. As well as lowering by 35 mm in relation to its distant relation – the standard Z4 – the spring and damper rates have been substantially modified towards more sports performance. In addition the wheel bearings and front and rear control arms have been replaced.
To counter sideways body roll, AC Schnitzer developed anti-roll kits on the front and rear axles. A further suspension highlight is the aluminium strut brace which optimally prevents torsion in the vehicle front.
Body & Interior
Even at first glance, the reshaped bonnet of the AC Schnitzer V8 Topster, with its noticable power bulge and large air outlet, already suggests that beneath it sits a very powerful engine which needs maximum cooling air flow, especially under full load. Also a new development is the front skirt which gives the Topster an even lower look and considerably improves downforce on the front axle at high speeds. Its large air inlet with integral grille ensures additional cooling for the engine and front brakes, and gives an unmistakable facial expression. Last but not least, the xenon headlamps integrated into the front skirt ensure that even at night, the driver has excellent visibility. To take into account the venting of the V8 engine, the new front side walls contain large air vents which, with their 3 chrome ribs and integrated flashers, are reminiscent of the deflectors on the AC Schnitzer ACS4.
Consequently the striking side skirts house air ducts for the rear brakes. The side skirts, which also give the TOPSTER an elongated look, form the harmonious transition to the rear side walls and the monstrous rear. The rear skirt accommodates not only an underfloor wing, but also the complete double exhaust system made of stainless steel.
The specially developed roof, with its supporting function, further reinforces the body of the V8 Topster. With its top, the Topster develops a new, homogeneous body side line – similar to a coupe. The integral rear roof wing in conjunction with the two-piece rear wing mounted left and right on the boot, improves the downforce of the entire body.
The interior of the AC Schnitzer V8 Topster is a combination of developments in the AC Schnitzer range available for many BMW models, and special one-off products. These include the racing bucket seats in leather. The airbag sports steering wheel, gear lever gaiter and handbrake cover are also provided in Alcantara with orange stitching. Velours foot mats also with orange applications and the leather logo round off the interior.
The AC Schnitzer V8 TOPSTER was developed as a technology showcase. In the equipment level and form shown here, this concept car would cost around 185 000 euros. Series production is not planned.