The Unlikely Hero in Automotive Noise Reduction: A Porsche 928
Modern vehicles are impressively quieter compared to their older counterparts, and we owe a significant part of this achievement to a uniquely modified Porsche 928. Displayed proudly at the Porsche Museum in Stuttgart, Germany, this extraordinary vehicle served as a noise test bed for over three decades.
Engineering Marvel: The 928’s Role in Noise Testing
In the late 1980s, Porsche engineers set out to meet stringent noise regulations and selected the 928 for this pivotal mission. It wasn’t just about any Porsche meeting the requirements; they needed a robust and versatile platform. According to Harald Mann, one of the original testers, the entry-level 924 and other models like the 944 and 911 were rejected due to their noise issues at low engine speeds or gearbox rattles.
The 928, built in 1989, became the hero of this initiative, specifically designed to measure and minimize tire noise—an area where no other noises could interfere.
Unique Modifications for a Quieter Tomorrow
To achieve such precision, the engineers had to make several modifications:
- Radiator Relocation: The radiator was placed in the front bumper, quite an unusual position for a car.
- Intake Silencer: A large, barrel-like silencer was added to the front of the car to minimize intake noise.
- Adaptive Cooling Fans: Bumps on the hood served as housings for fans, which were only activated when necessary to reduce noise.
- Oversized Muffler: A massive muffler was installed on the rear window to dampen exhaust sounds.
- Insulated Drivetrain: Both the drivetrain and gearbox were heavily insulated.
- Modified Fenders: Large rear fender flares were designed to accommodate various tire sizes.
High-Performance Yet Quiet
Despite these extensive modifications, the 928 retained its stock 5-speed manual gearbox, praised for its relatively low noise levels. The vehicle underwent rigorous testing, driving past an array of microphones to capture and average its noise levels in second and third gears.
One of the most fascinating aspects of this noise test car was its engine. Fitted with a prototype 5.4-liter V-8, this engine would eventually influence the development of the 928 GTS—the ultimate 928 model. Unveiled at the 1977 Geneva Auto Show, the 928 enjoyed a long production run until 1995. It remained Porsche’s only V-8 powered road car until the debut of the Cayenne in 2003.
Conclusion: A Legacy of Silence
The Porsche 928 noise test vehicle is more than just a museum piece; it’s a testament to the innovation and meticulous engineering that go into creating the quiet rides we enjoy today. As we stroll through the Porsche Museum, we’re reminded that sometimes, the quirkiest heroes leave the most lasting impact.
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Steven Hale, Editor of Automotive.fyi
