Does anyone know the numbers for power loss from crank-shaft to rear wheels through a PDK transmission compared to a standard manual? Is it the same as a manual? I am just curious if there is a penalty for going with PDK other than the additional weight.

 

PDK uses planetary gears and so is likely to have more power loss than a standard manual.

EDIT: I take it back. http://en.wikipedia.org/wiki/Epicyclic_gearing says that in general the planetary arrangement has superior power transmission.

 

I would love to see some percentage numbers to compare between power loss in PDK versus standard versus Tiptronic, or any automatic transmission. In automatics the power-loss percentage is surprisingly high.

 

I would expect the PDK to have more power loss than the manual. It's got more rotational weight and has the dual clutches submerged.

 

I don't know that Porsche released an official number for PDK, however I do know that Nissan was claiming something like 12% on the Borg Warner (I think) DSG they use. They said the clutches were much smaller than a traditional manual.

However I think Sport Auto found that to be false. I don't remember exactly so don't hold me to that. I am sure that Nissan claimed a very low number for drivetrain loss.

Seems counter-intuitive though. However the PDK transmission will make up for the drivetrain loss and weight with closer ratio gearing and faster shifts. That's why it will be interesting to see how Porsche's new 7 speed manual fairs in testing.

 

Not to get off topic but can the PDK be built to handle high HP mods?

 

I think Paul Tracy drove one in Battle of the Super Cars, and it was a high-horsepower modded Porsche Turbo. He crushed Tanner on that episode.

 

1234

 

Yeah. Not sure where I got that idea from. Anyway http://auto.howstuffworks.com/dual-c...nsmission1.htm is a fun read.

 

All we need are some dyno numbers from some stock Porsches with PDK. We can get a close percentage based on the factory hp rating at the crank versus the dyno numbers at the rear wheels.

 

Champion has some build threads over in the 997TT forum that might be a good place to start looking. Or contact them directly and see if they got a baseline pull on the car before they started modding it.

 

Getting a good clean dyno pull with a PDK is a little tricky.
http://sharkwerks.com/porsche/techni...s-ztadpol.html

A PDK Cay S is faster in both a 1/4 mile and a road course than a 6 speed even with the extra rotational weight. Do we really care what the parasitic loss % is? I guess I am sort of a bottom line guy. More interested in the checkered flag than the dyno sheet. YMMV

 

I am also a bottom-line guy, but in the process of forming my own conclusion about PDK, the % power loss is a solvable factor in the equation, adding to the list of "knowns."

It still makes my head hurt that 70 pounds of extra weigh, which on the track is a lot, is negated by faster shifts.

 

If you think you have a head ache, try looking up the 1/4tr mile results in the various automotive press comparrison tests, IIRC, for the @ 3200# Corvette ZO6 vs. the @ 4,000# Nissan GTR, in which the GTR tweaked the 'Vette's time, despite the Vette's presummed BHP/weight advantage via either, choose two, AWD &/or uninterupted power flow to the wheels because of its PDK gearbox.

Something to be said for faster, seamless, in Erica Jong's imortal words, "ziperless" shifts -

 

The quarter mile results do not surprise me, mainly with the advantage of AWD from a standing start, combined with the PDK. What does amaze me are the lap times; that even going around the twisties seems to be more largely affected by the PDK shifting than the extra 70+ pounds.