ICON: Turning Silver into Gold

Racing demands perfection. Every component, no matter how unassuming, can decide between triumph and defeat. Immediately before the 24 Hours of Le Mans in 2015, Porsche engineers Jens Maurer and Martin Füchtner are in for a shock. They discover wear and tear in places where there shouldn’t be. Their entry in the classic race is at risk. 

For four years, the Porsche factory team has been working toward one big goal: overall victory at Le Mans. It would be Porsche’s seventeenth time winning the legendary race. The sixteenth triumph was in 1998—
a long time ago—so there’s tremendous pressure to succeed. The Porsche 919 Hybrid, which has undergone extensive development for the 2015 season, looks like a spaceship. Beneath its sophisticated, aerodynamic carbon-fiber skin are a four-cylinder gasoline engine with turbocharging and two systems for energy recuperation. Together, they mobilize almost 1,000 hp. 

Now, on the Friday evening before the start, the final preparations are running under extreme stress. Used components are removed, meticulously examined for any abnormalities, and replaced with new parts for the race. The hybrid experts discover damage during their photographic and metrological inspection of two components. The problem affects metal pins measuring just seven centimeters in length. These pins are located on the inverter* of the hybrid system and transmit the entire power of over 400 kilowatts at a voltage of 800 volts. They’ve never exhibited any issues before. So what has changed? The engineers consider that this is the first time the 919 was driving in very high ambient temperatures. Could the material be responsible? 

Rapid troubleshooting soon indicates that the supplier produced a batch of these pins with a tin alloy instead of the required silver alloy. Visually they’re impossible to tell apart, but tin is much less resistant to heat. Now the engineers have to determine whether the converters intended for the race are using the incorrect pins made of tin or the heavy-duty silver pins. But how? Füchtner puts his mind to finding a solution and discovers that silver pins leave a gray line on white paper, while tin pins leave a yellowish one. The tests on the inverters that have been prepared for the race present a devastating result: yellow lines. All three cars to be entered into the race have been fitted with tin instead of silver pins and are at dangerous risk of failure. 

Normally, the inverters are assembled in Weissach in a dust-free clean room under laboratory conditions. At Le Mans, Füchtner and Maurer disassemble them in a steel hall behind the pits. Replacing the pins is like performing open-heart surgery without an operating room. But the Maurer-Füchtner duo has nerves of steel and their work is a success. At the end of the twenty-four-hour race, Porsche celebrates its first overall Le Mans victory of the twenty-first century. A double victory—all three Porsche 919 Hybrids cross the finish line. That’s how you turn silver into gold.

* The inverter converts the direct current from the battery into the three-phase current required by the drive. For energy recovery, it enables the charging current to reverse course and return to the battery.