DETROIT, MI, June 6, 2003 - A combination of high-technology refinement, global engineering and good old-fashioned ear tuning has ensured the dual exhaust system of the 2004 Pontiac GTO produces a legendary sound in a contemporary car - a rumbling, throaty exhaust note reminiscent of the classic original. Mechanically, the exhaust system on the GTO consists of two completely independent exhaust paths that run from the manifolds to the outlet pipes, ensuring there is no mixture of exhaust gases. However, creating the necessary "voice" of the vehicle required much more than simple mechanics.
The two exhaust outlets are side-by-side. But the system is a true dual exhaust system all the way.
"Anyone who has ever heard a classic GTO knows that distinctive 'sound,'" said Lynn Myers, Pontiac-GMC general manager. "It's very much a part of the character of both the GTO and Pontiac, so we knew we had to recreate that same feeling in the modern version."
The Holden Monaro, on which the new GTO is based, didn't have the "sound" Pontiac needed. "The Monaro is a great performance car, but it's sold as more of a luxury vehicle in Australia so the exhaust note was fairly quiet," said Robert Kraut, GTO marketing director. "From the beginning, everyone knew that the exhaust would have to be 'dialed-up' to give us that special sensory cue that says, 'This is a Pontiac.'"
Throughout the development of the system, exhaust system engineers in
opposite hemispheres worked extensively to ensure the
new GTO carried all of the audible emotion and virtues associated with its legendary predecessor.
"We had three main priorities for this vehicle right from the outset:
power, launch feel, and an exhaust note with lots of character,"
explained Dave Himmelberg, the GTO program engineering manager. "Our sound objective wasn't about making the exhaust loud. It was about bringing a smile to someone's face as soon as they turned the key."
Early in the vehicle development process, engineers test-drove an original 1964 GTO on loan from the Pontiac historical collection to acquaint themselves with its acoustical traits.
"We wanted to get a real good feel for the sound character of the vehicle," Himmelberg explained, "and that drive provided us with an acoustical baseline from which to start."
"We then listened to the 2002 Corvette, which also has a really good
sound with traits we were looking for. With those two
baselines, we pretty much had in mind what we wanted to accomplish. Our goal was to come in at a pass-by rate of just under 80 decibels, which is the legal sound limit in some states. But, we knew it couldn't be objectionable. It needed to be a pleasing 80
At that point, GM engineers in Australia (where the new GTO is built)
and North America worked diligently in a parallel effort to
develop an exhaust system that delivered the desired sound and performance characteristics.
"It became a true global effort because the exhaust needed to be developed
with parts available in Australia, but acoustically tuned
to the spirit of an American classic," Himmelberg said.
Dave Himmelberg, GTO Project Engineering Manager, shows an illustration of the system.
Through the efforts of engineers on two continents, a true dual exhaust
system was developed and acoustically tuned like a finely
crafted woodwind instrument, yet enables the heavy-breathing, low-back pressure needs of the 340-horsepower LS1 V8
powerplant. It consists of:
"We analyzed and re-analyzed sound qualities at every point of the performance curve," Himmelberg said. "We wanted the rumble
at start up, more of a throaty roar during acceleration, and it needed to have a pleasing presence at cruise speeds."
However, the true test came down to what the exhaust note sounded like to the human ear, and the emotions it evoked.
A Quicksilver Metallic prototype car with the duals installed.
"We had about five prototype builds of the system," Himmelberg recalled,
"and for each of them, it really boiled down to listening to them on the
GTO. We had 14 different scenarios where we'd listen to and analyze the
sound - during acceleration, pass-by on
streets, pass-by on highways, idle . . . you name it."
Another view of a prototype car with duals installed.
"In the end, we knew we had exactly the sound we wanted. It's hard to hear it and not just grin."
General Motors Corp. (NYSE: GM), the world's largest vehicle manufacturer,
employs 342,000 people globally in its core automotive business and subsidiaries.
Founded in 1908, GM has been the global automotive sales leader since 1931.
GM today has
manufacturing operations in 32 countries and its vehicles are sold in more than 190 countries. In 2002, GM sold more than 8.6 million cars and trucks, nearly 15 percent of the global vehicle market. GM's global headquarters is at the GM Renaissance Center in Detroit. More information on GM and its products can be found on the company's consumer website at www.gm.com.
Look for sound samples of the car to appear here soon. There will be some .WAV files to hear or download.
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