a COOL approach to forced induction

The "horsepower war" waged between Detroit's Big Three in the 1960's seems more like a cafeteria food-fight next to what's going on in Germany these days. 500 horsepower cars are daily commuters, and 400 horsepower cars don't even blip the enthusiast radar. In times like these, power-hungry enthusiasts often turn to Mercedes-Benz' bi-turbo and "kompressor" models... but for some, even a twin-turbo V12 isn't enough.

Enter RENNtech, where enough is never enough and too much is considered a good start. "We actually had one customer complain that his new S600 was too fast!" laughs Hartmut Feyhl, who started RENNtech in 1989 (after 12 years at AMG, eventually becoming that company's technical director). "Just one, though - everyone always wants more." To get More out of their engines, the crew at RENNtech approaches forced induction cars as complete systems. "We were looking for a total power solution, not just a component 'fix' like a pulley or a loud exhaust. That way, we could be sure that all our parts worked together to increase power, and also maintain the reliability and refinement of the stock vehicle."

RENNtech 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 throttle - 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, and without the kind of engine wear that normally comes with more heat."

With that goal in mind, Feyhl and company developed RENNtech's intercooler pump upgrade, which drops intake temperatures and allows the engine to run even more boost pressure with more cool, oxygen-rich air. "It's a must-have." says Feyhl, who has seen horsepower climb well beyond the magic '700' mark on RENNtech's chassis dyno. RENNtech's upgrade takes the form of a complete redesign of the intercooler systems on the AMG 55 and 65 cars, as well as the 600s and SLR. The stock pumps are replaced with RENNtech-specific pumps with almost double the capacity of outgoing units. Dedicated radiators are installed, and the new pieces are integrated into the engine bay almost invisibly. As Feyhl points out, “It looks like it’s supposed to be there.”

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.”

The intercooler pump upgrade is available for Mercedes' "kompressor" and V12 turbo cars, and works in concert with RENNtech's ECU software upgrades, throttle-bodies, and pulley kits to obtain maximum results.