 The Stuttgart-based brand
2008
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The GLK Pikes Peak Rally Racer is king of the hillInspired by the winged, unlimited-class rally cars of the famed Pikes Peak Hill Climb, RENNtech set about creating a GLK that could master the pack and leave the rest chewing gravel.
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But, this wild GLK has a few surprises beneath its
menacing exterior. Hybrid powertrains are generally associated with fuel
efficiency and lower emissions. However, RENNtech has taken one more benefit
of the hybrid principle to turn the GLK into a formidable performer. By combining
an electric motor in parallel with the 3.5 litre V6 petrol engine, RENNtech
has been able to capture the impressive torque that characterises electric
motor drives, adding 54 Nm to enhance the GLK's performance off-the-line
and out of corners. Using a hybrid drive in a hill climb setting has the
added advantage of maintaining thrust at higher altitudes, when internal
combustion engines - which depend on ambient air - start to wheeze. The
specialist Mercedes tuning company has also worked its magic on the base
3.5 litre V6 unit, using components from the latest Mercedes-Benz
high-performance 3.5 litre V6 Sport engine. These include a special intake
manifold, cams and cylinder heads, to which RENNtech has added its own long-tube
headers, composite air intake and RENNtech ECU software. Engine output is
up to approximately 350 hp, augmented further by the electric motor from
the hybrid drive. The additional 72 volt drive is run by 12 volt plug-in
batteries. RENNtech is currently working on a nickel-hydride solution with
regenerative charging for additional range. "The GLK Rally Racer Hybrid is
a fully-functioning test bed," explains Hartmut Feyhl, founder and President
of RENNtech. "We will use this vehicle as a proof-of-concept, which we will
develop and enhance throughout next year."
"With the Rally Racer, we have really increased
the car's performance," continues Feyhl. "Together with the more aggressive,
sporting look, we have created a powerful and exciting package." It is also
worth noting that, despite the performance enhancements, RENNtech has succeeded
in improving the fuel economy of the Rally Racer compared with the original
version, "proving that high performance and efficiency can coexist," adds
Feyhl. Bearing in mind that the Rally Racer is built for speed on tough terrain,
RENNtech opted to forego creature comforts, cutting the weight of the standard
GLK by removing most of the sound insulation and replacing the Mercedes-Benz
seats with lightweight carbon-fibre buckets. Engineers also fitted a full
roll cage and moved several components towards the rear of the vehicle to
create an almost perfect 50:50 front/rear weight distribution for improved
handling on tight, demanding rally stages. Another significant handling
modification comes from the custom coil-over suspension. Made to RENNtech
specifications by suspension supplier KW, the package allows for adjustments
in height, rake, damping rate, camber and toe-in. Extra stopping power is
provided for the Rally Racer courtesy of an in-house RENNtech brake combo
featuring massive 412mm, 2-piece rotors with 8-piston callipers at the front,
and 356mm discs grabbed by 4-pot callipers at the rear. Lightweight 20 inch
3-piece, 5-spoke RENNtech wheels in a "Sniper Gray" anthracite finish, clad
in NT05 275/40 20 Nitto rubber at the front and NT05 315/35 20 at the rear,
fill the prominent wheel flares that underscore this GLK's performance potential.
Although extensive exterior revisions were made
to accommodate the larger wheels and brakes and to widen the track, the focus
of bodyshell modifications was enhanced aerodynamic efficiency. RENNtech
used the latest in Computational Fluid Dynamics (CFD) software to develop
the package. The front splitter, rear diffuser and lower side skirts help
direct airflow underneath the GLK Rally Racer to reduce drag and produce
added downforce, while improving high speed stability at the rear. The rear
wing elements also serve an important aerodynamic purpose and add emphasis
to the aggressive edginess of the original GLK design. From a visual perspective,
RENNtech engineers successfully melded their aerodynamic modifications with
the flared wheel arches to create a powerful side line that highlights the
dynamic thrust of the Rally Racer. "The GLK was a great starting point for
this project," says Hartmut Feyhl, "It has excellent underpinnings for
performance tuning and I think the overall look really suits it." "The GLK
gave us a great deal of scope for bringing together form and function. For
the RENNtech GLK, performance may have been the primary goal, but it also
looks the part," he adds.