- 28 Aug 08, 17:26#62068
http://www.motortrend.com/av/features/1 ... index.html
After Nissan announced in May of this year that its 480-horsepower, all-wheel-drive GT-R lapped Germany's infamous 20.8-km (12.9 miles) Nurburgring Nordschleife in a time of 7:29, Viper people became restless. Then, just a month later, following Chevrolet's declaration that its 638-horsepower supercharged Corvette ZR1 was the king of the hill, breaking the GT-R's record with a time of 7:26, Viper people became downright mad. Not the folks who work for Dodge, mind you, but the members of the Viper Club of America, a group of Viper fanatics that in fact stretches its arms well beyond America, as far as Japan and Germany. Sick and tired of hearing about other cars setting records at the Nordschleife, they wanted to see their pride and joy-namely, Dodge's new track-attacking 600-horsepower Viper ACR (American Club Racer)-take a shot at the record books. But what could they do about it?
Well, they could (and did) bug Dodge-specifically, the Street & Racing Technology team-to the point that SRT said, What the heck, let's go for it. So SRT rented the Nordschleife for a half-day (at a cost of $2000 Euro per hour), shipped two ACRs over to Germany, hired a pro driver through Zakspeed (a race team that runs Vipers in the ADAC Zurich 24h Race at the Nrburgring), and hoped for good weather and, more important, a lap time quicker than 7:26. And, for posterity, the SRT team figured having a media outlet on-hand was a wise idea, so they invited Motor Trend
1.Driver had never driven the ACR before.
2. He broke the record on his third lap in the car.
3. He missed two shifts (not just one).
4. He faced a pretty strong headwind on that final straight - so much so that the Viper's stock gearing and enormous down force made it impractical to use 5th gear.
From the Motor Trend article:
YOU'RE looking at Dodge's answer to the Porsche 911 GT3 RS or Lotus Exige, a road car you can drive to the track, hot lap all day, and drive back home, tires, brakes, and ego intact. The Viper ACR is raw. It's wired. And it's probably the best weekend racer yet from Detroit.
The ACR has exactly the same power and torque as the regular Viper-600 horses and 560 pound-feet. The engine drives through a smaller dual plate clutch that reduces rotating inertia by 18 percent and the latest iteration of the Tremec T6060 six-speed that includes triple-cone synchros on first and second, and 10-percent-wider gears to manage the torque. The new GKN ViscoLok diff features its own sump to quicker generate the hydraulic pressure needed to actuate the limited-slip clutches faster, yet more progressively and with greater precision.
Most of the time, effort, and development dollars have been spent on stuff that makes the ACR go faster through the twisty bits-suspension, brakes, wheels and tires, and aerodynamics. Especially the aerodynamics. Just chew on this for a moment: At 150 mph, the regular Viper coupe generates 100 pounds of downforce; at the same speed, the Viper ACR generates 1000 pounds of downforce.
That giant carbon-fiber rear wing is the most obvious reason why. But there's also a new carbon-fiber front splitter that extends way back under the car and incorporates seven steps to diffuse the airflow. The new hood louvers unveiled with the 600-horsepower engine upgrade a year ago play a part, too. "We knew we were going to do a new ACR, so we moved the louvers forward to help change the aero balance of the car," says SRT boss Herb Helbig.
Suspension changes include race-style KW shocks all around that can be adjusted for stiffness and ride height, springs twice as stiff as those in a normal Viper, and a beefier front stabilizer bar. Forged "Sidewinder" alloy wheels save 30 pounds of unsprung weight, and new two-piece StopTech brake rotors save a further 30. Michelin Pilot Sport Cup tires-basically barely legal race rubber-are standard.
The standard ACR is 40 pounds lighter than the regular Viper coupe. An optional "Hard Core" pack saves an extra 40 pounds through the removal of the audio system, underhood silencer pad, trunk carpet, and tire inflator. The radio is replaced by a lightweight cover that can be configured to mount the lap timer that comes with the package. Hard-core, indeed.
After Nissan announced in May of this year that its 480-horsepower, all-wheel-drive GT-R lapped Germany's infamous 20.8-km (12.9 miles) Nurburgring Nordschleife in a time of 7:29, Viper people became restless. Then, just a month later, following Chevrolet's declaration that its 638-horsepower supercharged Corvette ZR1 was the king of the hill, breaking the GT-R's record with a time of 7:26, Viper people became downright mad. Not the folks who work for Dodge, mind you, but the members of the Viper Club of America, a group of Viper fanatics that in fact stretches its arms well beyond America, as far as Japan and Germany. Sick and tired of hearing about other cars setting records at the Nordschleife, they wanted to see their pride and joy-namely, Dodge's new track-attacking 600-horsepower Viper ACR (American Club Racer)-take a shot at the record books. But what could they do about it?
Well, they could (and did) bug Dodge-specifically, the Street & Racing Technology team-to the point that SRT said, What the heck, let's go for it. So SRT rented the Nordschleife for a half-day (at a cost of $2000 Euro per hour), shipped two ACRs over to Germany, hired a pro driver through Zakspeed (a race team that runs Vipers in the ADAC Zurich 24h Race at the Nrburgring), and hoped for good weather and, more important, a lap time quicker than 7:26. And, for posterity, the SRT team figured having a media outlet on-hand was a wise idea, so they invited Motor Trend
1.Driver had never driven the ACR before.
2. He broke the record on his third lap in the car.
3. He missed two shifts (not just one).
4. He faced a pretty strong headwind on that final straight - so much so that the Viper's stock gearing and enormous down force made it impractical to use 5th gear.
From the Motor Trend article:
YOU'RE looking at Dodge's answer to the Porsche 911 GT3 RS or Lotus Exige, a road car you can drive to the track, hot lap all day, and drive back home, tires, brakes, and ego intact. The Viper ACR is raw. It's wired. And it's probably the best weekend racer yet from Detroit.
The ACR has exactly the same power and torque as the regular Viper-600 horses and 560 pound-feet. The engine drives through a smaller dual plate clutch that reduces rotating inertia by 18 percent and the latest iteration of the Tremec T6060 six-speed that includes triple-cone synchros on first and second, and 10-percent-wider gears to manage the torque. The new GKN ViscoLok diff features its own sump to quicker generate the hydraulic pressure needed to actuate the limited-slip clutches faster, yet more progressively and with greater precision.
Most of the time, effort, and development dollars have been spent on stuff that makes the ACR go faster through the twisty bits-suspension, brakes, wheels and tires, and aerodynamics. Especially the aerodynamics. Just chew on this for a moment: At 150 mph, the regular Viper coupe generates 100 pounds of downforce; at the same speed, the Viper ACR generates 1000 pounds of downforce.
That giant carbon-fiber rear wing is the most obvious reason why. But there's also a new carbon-fiber front splitter that extends way back under the car and incorporates seven steps to diffuse the airflow. The new hood louvers unveiled with the 600-horsepower engine upgrade a year ago play a part, too. "We knew we were going to do a new ACR, so we moved the louvers forward to help change the aero balance of the car," says SRT boss Herb Helbig.
Suspension changes include race-style KW shocks all around that can be adjusted for stiffness and ride height, springs twice as stiff as those in a normal Viper, and a beefier front stabilizer bar. Forged "Sidewinder" alloy wheels save 30 pounds of unsprung weight, and new two-piece StopTech brake rotors save a further 30. Michelin Pilot Sport Cup tires-basically barely legal race rubber-are standard.
The standard ACR is 40 pounds lighter than the regular Viper coupe. An optional "Hard Core" pack saves an extra 40 pounds through the removal of the audio system, underhood silencer pad, trunk carpet, and tire inflator. The radio is replaced by a lightweight cover that can be configured to mount the lap timer that comes with the package. Hard-core, indeed.
You do not have the required permissions to view the files attached to this post.
"Sanity and happiness are an impossible combination".
Mark Twain
Mark Twain
