2008 has been a busy year for RENNTECH; one that has already seen the Florida-based Mercedes tuner named McLaren’s US service and support agent for the RML-built SLR McLaren 722GT and seen the company announce a 695 hp V12 tuning package that boosts power while returning an additional 2 mpg highway. Mercedes-Benz’s AMG division is having a busy year, as well, with near-record sales numbers and the release of a new SL63 AMG roadster generating lots of interest from fans and collectors. The birth of the highly-anticipated rev-happy SL63 effectively signals “the end of the road” for the torque-monster Kompressor motor in regular production AMG cars, with only the G55 and SLR roadster remaining.
“The 6.2 is really a great motor,” explains Hartmut Feyhl, RENNTECH’s president and ex-technical director at AMG North America, “but there are many 55 owners who have gotten used to the immediate, low-end torque and response from the Kompressor motor, and we haven’t forgotten them.”
This morning, RENNTECH introduced a new “Package Plus” option for the much-loved 55 Kompressor motor. The new PKG Plus adds RENNTECH’s intercooler system, a new extra large crank pulley, and an all-new ECU/TCU software solution that noticeably improves the midrange torque, drivability, and fuel economy in RENNTECH’s already potent tuning packages.
Those performance gains are not the whole story, however. In developing the PKG Plus upgrades, RENNTECH went looking for a total solution, rather than a quick-fix component swap, and over a year ago identified the intercoolers as the “Achilles’ heel” of the turbo and kompressor cars their customers were bringing in. The cars made good peak power, but even stock power dropped off quickly as the temperatures rose. “In some cars, the superchargers were being ’switched off’ almost completely,” explains Feyhl. “We knew, then, that simply getting more air into the engines with a bigger pulley or ECU tune - which was making quite a bit more more power already - wasn’t enough. We needed to offer consistent power, so our customers could make back-to-back-to-back runs at maximum output, without the engine wear that normally comes with more heat.”
The results are impressive: RENNtech’s intercooler upgrade dropped intake temperatures an average of 10 degrees Celsius across the operating range, and the time it took to get the engine’s temperatures back to “normal” after a dyno run was greatly reduced. “We used to have to wait almost 2 minutes between dyno runs to the get the temperatures back down, even with big fans blowing,” says Feyhl. “Now it takes about 20 seconds.”
Torque is also improved throughout the engine’s midrange, thanks to the latest, second-generation software developed entirely in-house by RENNTECH’s engineering staff.
RENNTECH chose to showcase the new upgrades on Feyhl’s own CLS55 RENNTECH PKG5 Plus, which makes full use of PKG 5’s carbon fiber airbox, stainless steel headers, and larger 78 mm throttle-body to produce over 600 hp and 630 lb-ft of consistent, reliable torque, capable of sending the CLS to speeds in excess of 200 mph. Feyhl’s CLS delivers that power to the road via RENNTECH’s new 3 pc. performance wheels and Nitto Invo tires, using RENNTECH’s adjustable camber bushings, toe links, and v2 digital lowering module to keep the back end under control. Adding to the aerodynamic (and aesthetic) qualities of the CLS are RENNTECH’s rear decklid spoiler and carbon fiber rear diffuser.
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