Inside Porsche's Sweet New Dual-Clutch Gearbox
#1
07-12-2008, 08:39 PM
Inside Porsche's Sweet New Dual-Clutch Gearbox From Edmunds
DETROIT We're still months away from seeing the revised 2009 Porsche 911 lineup along with its high-tech new Porsche Doppelkupplung (PDK) dual-clutch automated manual transmission in showrooms. But thanks to ZF Friedrichshafen AG, the German transmission specialist with whom Porsche developed PDK, we can at least get a look at the complex guts of the transmission that's threatening to become the industry's new performance-car standard.
Porsche finally is launching its first production-car automated manual, the seven-speed PDK following industry innovator Volkswagen/Audi and more recent intros of dual-clutch transmissions from BMW, Mitsubishi and Nissan.
Last month, we gave a pretty good rundown of the more powerful engines and other revisions for the '09 911 lineup, but we figured who wouldn't want to see the PDK's innards in all their glory?
Apart from the PDK's stated performance advantage 4.5 seconds to 60 mph, or two-tenths of a second quicker than the six-speed manual for the standard 911 Carrera (and 4.3 seconds if you pop for the overblown Sports Chrono Package Plus) we expect that in these economy-focused times, Porsche may choose to highlight how PDK pushes the latest 911 to deliver some fist-bump-worthy fuel efficiency.
A basic 911 Carrera currently is rated at 18 mpg city/24 mpg highway, or about 22 mpg combined. But for the new 911's driveline, the combination of the newly direct-injected horizontally opposed six-cylinder engines and PDK make the new 911 some 13 or 14 percent more efficient than the current car, so a rear-drive 911 coupe might generate something approaching 25 mpg combined. Not too shabby.
Porsche's conventional manual trumps the PDK 'box in terms of transmission losses. However, the PDK's seventh gear allows the engine to operate in a sweeter spot of its operating range which improves overall powertrain efficiency. Though it is a tall cruising gear, 7th gear in the PDK still provides enough mechanical advantage that the 911 can reach its top speed, while PDK's 1st- through 6th-gear ratios are essentially identical to those of the six-speed manual.
We don't yet know what Porsche will charge for the PDK option for the '09 911 model line, but British publications are reporting the price of the PDK option at £2,338 that, if directly converted to dollars, equals $4,635. But it's likely U.S. pricing will be more in line with the $2,700 BMW gets for its M double-clutch transmission.
According to development partner ZF, the 7DT 45, as it's known within the company, is capable of handling engine speeds up to 8,000 rpm, but torque limitations mean that the current PDK won't be able to back the more-powerful Turbo and GT3 variants of the 911. The Boxster purportedly gets PDK as part of its scheduled face-lift next year.
ZF said it also has a transaxle version of PDK capable of working in midengine cars with rear- or all-wheel drive.
What this means to you: All the new dual-clutch automated manuals are convincing substitutes for a clutch-pedal manual transmission. Now it's up to enthusiasts to decide if automated manuals are better. Bill Visnic, senior editor, Edmunds AutoObserver
DETROIT We're still months away from seeing the revised 2009 Porsche 911 lineup along with its high-tech new Porsche Doppelkupplung (PDK) dual-clutch automated manual transmission in showrooms. But thanks to ZF Friedrichshafen AG, the German transmission specialist with whom Porsche developed PDK, we can at least get a look at the complex guts of the transmission that's threatening to become the industry's new performance-car standard.
Porsche finally is launching its first production-car automated manual, the seven-speed PDK following industry innovator Volkswagen/Audi and more recent intros of dual-clutch transmissions from BMW, Mitsubishi and Nissan.
Last month, we gave a pretty good rundown of the more powerful engines and other revisions for the '09 911 lineup, but we figured who wouldn't want to see the PDK's innards in all their glory?
Apart from the PDK's stated performance advantage 4.5 seconds to 60 mph, or two-tenths of a second quicker than the six-speed manual for the standard 911 Carrera (and 4.3 seconds if you pop for the overblown Sports Chrono Package Plus) we expect that in these economy-focused times, Porsche may choose to highlight how PDK pushes the latest 911 to deliver some fist-bump-worthy fuel efficiency.
A basic 911 Carrera currently is rated at 18 mpg city/24 mpg highway, or about 22 mpg combined. But for the new 911's driveline, the combination of the newly direct-injected horizontally opposed six-cylinder engines and PDK make the new 911 some 13 or 14 percent more efficient than the current car, so a rear-drive 911 coupe might generate something approaching 25 mpg combined. Not too shabby.
Porsche's conventional manual trumps the PDK 'box in terms of transmission losses. However, the PDK's seventh gear allows the engine to operate in a sweeter spot of its operating range which improves overall powertrain efficiency. Though it is a tall cruising gear, 7th gear in the PDK still provides enough mechanical advantage that the 911 can reach its top speed, while PDK's 1st- through 6th-gear ratios are essentially identical to those of the six-speed manual.
We don't yet know what Porsche will charge for the PDK option for the '09 911 model line, but British publications are reporting the price of the PDK option at £2,338 that, if directly converted to dollars, equals $4,635. But it's likely U.S. pricing will be more in line with the $2,700 BMW gets for its M double-clutch transmission.
According to development partner ZF, the 7DT 45, as it's known within the company, is capable of handling engine speeds up to 8,000 rpm, but torque limitations mean that the current PDK won't be able to back the more-powerful Turbo and GT3 variants of the 911. The Boxster purportedly gets PDK as part of its scheduled face-lift next year.
ZF said it also has a transaxle version of PDK capable of working in midengine cars with rear- or all-wheel drive.
What this means to you: All the new dual-clutch automated manuals are convincing substitutes for a clutch-pedal manual transmission. Now it's up to enthusiasts to decide if automated manuals are better. Bill Visnic, senior editor, Edmunds AutoObserver
#3
07-20-2008, 05:02 PM
I'm still quite disappointed about the shifting mechanism. They should have used paddle shifters instead.
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