Now retired from service, Porsche engineers relied on this odd creation for a very specific purpose
by Khris Bharath on June 7, 2024, 10:00Forget slick lines and a powerful engine. This is unlike any other Porsche 928 that you’ve seen before. This silver example cobbled together from mismatched components and resembling something out of a Mad Max film, is actually a Porsche legend. What you’re looking at is the world’s quietest 928, and its story is both odd and interesting. For over three decades years, this unique-looking Porsche fulfilled a single purpose: to silence its peers. Commissioned in 1989, it has cruised the Weissach test track, stuffed with insulation, and helped Porsche engineers in developing quieter tires owing to more stringent noise rules and regulations that came into force back in the late ‘80s and early ‘90s.
- Developed for Noise testing
- Relocated Radiator
- Giant Intake Silencer
- Cotton-Wrapped Engine Bay
- Massive Muffler Mounted On Rear Windscreen
- Insulated Undercarriage
- Surprisingly Quiet (63 db)
A Porsche Test Mule Designed To Measure Noise
To truly isolate the noise, the engineers went full Dr. Frankenstein. The radiator sat on a special frame mounted ahead of the front bumper and the intake was rerouted through a giant barrel – basically a noise silencer on steroids. The engine compartment got the same treatment, wrapped in cotton to keep those precious decibels in check. Cooling for the V8 was done via two fans housed in a scoop that sat on the hood.
Moving on to the exhaust, picture this: a massive muffler strapped to the rear window, with an unusually long exhaust pipe hanging behind the tailgate. Not exactly a looker I know, but function over form, which is the Porsche way. The undercarriage wasn’t spared either. The whole transaxle and gearbox were also wrapped in insulation material, further reducing noise. The results are astounding. This Porsche produced [just 63 decibels, which was unheard of at the time,](https://newsroom.porsche.com/en/2024/history/porsche-928-noise-test-vehicle-development-36389.html) especially given the required legal maximum was 75 decibels at 31 mph. It was in fact so quiet that at one point, even Pirelli used this test mule.
So mission accomplished then. But why a 928? Well, according to Harald Mann who was for over 40 years at Porsche as a trained mechanic and worked on this project, power at low rpm was crucial. He further adds that the 911 would be too loud and the 944? Forget it; that gearbox wailed like a banshee. The 928, with its smooth shifting manual transmission and powerful front-engined V8, was the ideal test mule. Speaking of the engine, this wasn’t your typical Porsche V8 either.
During the early 1990s development of the 928 GTS, Porsche was working on two engines: a high-revving screamer and a torque monster. The former triumphed, but what about the torquey V8? Well, it ended up in this noise-testing oddity. A leftover powerhouse in a stripped-down shell, this 928 is a one-of-a-kind creation. Now retired from service, this Porsche 928 now sits on display at the Porsche Museum in Zuffenhausen.
Khris Bharath
Khris is a Mechanical Engineer and a classic car aficionado, who adores his Jags, Alfas, and old-school American muscle cars. He keeps tabs on everything from super exotics like an old EB 110 to the latest from Lucid and geeks out on three-row family haulers. Formula One remains very close to his heart, and he diligently makes time to tune in for the Grand Prix on Sundays. Khris also loves his road trips and he prefers a stick shift over an auto. Read full bio