PDCC - thoughts
#32
07-12-2012 | 11:21 AM
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Not true, Chuck. PASM is always "on" and so is PDCC. They simply have different operating modes. In the case of PASM it is Normal or Sport, both of which are active algorithms. With PDCC there appear to be three, Normal, Sport and Sport+ triggered either by the selection of Sport+ mode using SC+ (source: 991 brochure), or as a result of the connection between PASM and PDCC as described here (source 991 iManual): "When you select a chassis setup in Porsche Active Suspension Management (PASM) the PDCC system automatically activates the corresponding on-road driving programme". Be assured though that both are always active.
The Tech manual says:
There is no separate control for PDCC. When PASM tuning [normal or sport] is selected, PDCC activates the relevant control program automatically. I'm not sure the degree of control in each mode as it varies with several parameters.
ChuckJ
Last edited by ChuckJ; 07-12-2012 at 03:26 PM.
#33
07-12-2012 | 01:56 PM
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Here's an interesting article with pictures that I came across - apologies if its a repost:
Edmunds Insideline - Suspension Walkaround: 2012 Porsche 911 Carrera S
"...The stabilizer bar link (green) is hydraulic, as is its opposite number on the other side of the car. A central computer looks at body height sensors, steering angle and a host of other factors to determine how to make them behave.
On straight roads they can go limp to essentially remove the stabilizer bar from the picture for a smooth ride. In corners they can be made to "overdrive" what the stabilizer bar could otherwise do on its own to utterly eliminate body roll. Or the computer can dial in any amount of roll stiffness in between, and it can change its mind in real time as road conditions or driver inputs fluctuate.
Porsche calls this Porsche Dynamic Chassis Control (PDCC) and it's the first time they've fit it to a 911-series vehicle. Whatever you call it, it flat works. This very car pulled 1.04 g on our skidpad, and some of the credit has to be put down to the way this system can make use of all four tires instead of leaning heavily on the outside ones.
You could theoretically achieve the same skidpad prowess with a pair of very big stabilizer bars, but then the car would ride like Grade A dog doo. Conversely, a hydraulic anti-roll system such as this doesn't need a physical stabilizer in between the left and right struts at all, but in that case there'd be no fail-safe if the system developed a fault."
Edmunds Insideline - Suspension Walkaround: 2012 Porsche 911 Carrera S
"...The stabilizer bar link (green) is hydraulic, as is its opposite number on the other side of the car. A central computer looks at body height sensors, steering angle and a host of other factors to determine how to make them behave.
On straight roads they can go limp to essentially remove the stabilizer bar from the picture for a smooth ride. In corners they can be made to "overdrive" what the stabilizer bar could otherwise do on its own to utterly eliminate body roll. Or the computer can dial in any amount of roll stiffness in between, and it can change its mind in real time as road conditions or driver inputs fluctuate.
Porsche calls this Porsche Dynamic Chassis Control (PDCC) and it's the first time they've fit it to a 911-series vehicle. Whatever you call it, it flat works. This very car pulled 1.04 g on our skidpad, and some of the credit has to be put down to the way this system can make use of all four tires instead of leaning heavily on the outside ones.
You could theoretically achieve the same skidpad prowess with a pair of very big stabilizer bars, but then the car would ride like Grade A dog doo. Conversely, a hydraulic anti-roll system such as this doesn't need a physical stabilizer in between the left and right struts at all, but in that case there'd be no fail-safe if the system developed a fault."
I love these types of stories,....did they happen to test a non-PDCC equipped car right next to it? They most likely would of had the same type of glowing remarks for a car equipped without it. Without some sort of control in the testing it's all just opinion. Statistics class 101 here. What if the non-PDCC car pulled a 1.03g? Would everyone just line up to spend $3.2k for .01g gain in cornering? Heck a 2lb difference in tire pressure or tire wear could easily make more of a difference.
In the earlier posted PDCC comparison video why wasn't the comparison done between 991s instead of a 991 and a 997? Could it have been that the inherent new much wider track of the 991, revised PASM & suspension settings would have made it look like almost no difference?
I think this topic could be debated till the next version of the 911 comes out with passionate and good views from both sides.
It all boils down to the individual,.....if it makes you sleep better at night checking that option box, by all means it's money well spent. And that's all that really matters right?
Last edited by Rocket_boy; 07-12-2012 at 01:58 PM.
#34
07-12-2012 | 03:25 PM
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....
In the earlier posted PDCC comparison video why wasn't the comparison done between 991s instead of a 991 and a 997? Could it have been that the inherent new much wider track of the 991, revised PASM & suspension settings would have made it look like almost no difference?
I think this topic could be debated till the next version of the 911 comes out with passionate and good views from both sides.
It all boils down to the individual,.....if it makes you sleep better at night checking that option box, by all means it's money well spent. And that's all that really matters right?
In the earlier posted PDCC comparison video why wasn't the comparison done between 991s instead of a 991 and a 997? Could it have been that the inherent new much wider track of the 991, revised PASM & suspension settings would have made it look like almost no difference?
I think this topic could be debated till the next version of the 911 comes out with passionate and good views from both sides.
It all boils down to the individual,.....if it makes you sleep better at night checking that option box, by all means it's money well spent. And that's all that really matters right?
The video you refer to is interesting. Upon looking at it again it really seems that they are both 997's. Have a look carefully, I may be utterly wrong. No matter it explained a lot to me about pdcc.
Agree it does boil down to individual preference. I think most potential owners will have plenty of reasons to sleep well no matter what they tick on the options box! They are after all ordering a wonderful car.
Last edited by Haku; 07-12-2012 at 03:50 PM.
#36
07-12-2012 | 05:43 PM
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Had a discussion with a P-car "expert" and the PDCC topic came up. He made a comment that has since been going around my head. What are the takes from those that drive these things hard ?
The concern was the PDCC is not a good idea if you are a relative novice and never track the car or drive the car to its limits. The reason is that the roll during hard cornering acts like a built in G-meter for the driver, i.e. you will notice the roll and know how hard you are pushing it. With the PDCC this indication has been removed and you are no longer able to judge as nicely how far you are away from disaster.
The suggestion was that this does not matter for the experienced track driver as he will compensate quickly for this.
This kind of agrees with a comment made by one of the testers in a recent EVO article where he complained about the car letting go without warning when pushed hard into corners.
What do you think ? True or BS ?
Rainier
The concern was the PDCC is not a good idea if you are a relative novice and never track the car or drive the car to its limits. The reason is that the roll during hard cornering acts like a built in G-meter for the driver, i.e. you will notice the roll and know how hard you are pushing it. With the PDCC this indication has been removed and you are no longer able to judge as nicely how far you are away from disaster.
The suggestion was that this does not matter for the experienced track driver as he will compensate quickly for this.
This kind of agrees with a comment made by one of the testers in a recent EVO article where he complained about the car letting go without warning when pushed hard into corners.
What do you think ? True or BS ?
Rainier
#37
07-13-2012 | 01:00 AM
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On the other hand, Porsche is very sensitive about the 911's (long outmoded) reputation for leaving its owners in a ditch, back to front, upside down and on fire
Taming the rear end has long been an obsession. And that inevitably means pandering to the novice (in the "vanilla" Carreras)
#38
07-13-2012 | 05:41 PM
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They didn't. PDCC is an option, not part of the standard car. But it makes the car relatively faster, the twistier the road/circuit. How is that bad, particularly when you can leave it off the order sheet?
On the other hand, Porsche is very sensitive about the 911's (long outmoded) reputation for leaving its owners in a ditch, back to front, upside down and on fire
Taming the rear end has long been an obsession. And that inevitably means pandering to the novice (in the "vanilla" Carreras)
On the other hand, Porsche is very sensitive about the 911's (long outmoded) reputation for leaving its owners in a ditch, back to front, upside down and on fire
Taming the rear end has long been an obsession. And that inevitably means pandering to the novice (in the "vanilla" Carreras)
Around any given track, how do you know it's faster with PDCC? Are there any back to back tests with valid numbers? We know it reduces lean a bit, but that in itself won't make a car quicker unless a traction loss is incurred with the non-PDCC car.
As usual all we know is that a 991 S did a certain time around the Nürburgring,....most likely loaded with sport PASM, PCCB, PDCC, etc. Now how can we tell what option(s) actually made the biggest difference? We simply can't, you can only guess. If anyone has actual timings of a PDCC and non PDCC car back to back, please post.
As I mentioned before when the Cayman S came out in 2006 a fully loaded one with PASM, PCCB, SC, 19" wheels, etc. was only about 14 seconds faster compared to a bare bones version. On an 8 minute timing that's about a .03% improvement, for about $12k in price. How does that translate to the street?,....basically nil for $12k.
I'm willing to bet that PDCC is responsible for about 3 ~ 5 seconds on an average track, with PCCB being the best time saver as it is a serious weight reduction, less un-sprung weight on the suspension and fantastic fade resistance. If this is worth it to you, buy it!...money well spent.
As with any Porsche option buy it because it is what you want and will use. I doubt there will be any significant difference on the street between a loaded vs. base same model 991.
#39
07-16-2012 | 01:21 PM
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McLaren's suspension
But the PDCC-like effect probably explains a) why Clarkson said the MP412C was the most comfy supercar ever tested and at the same time b) many journalists agree that the steering in the McLaren doesn't hold a candle to the 458.
I drove a 991S with sport PASM on track (no PDCC), minimal roll at entry speeds up to 115-120 and no harshness [although the track is no place to assess a suspension's compliance].
I hope the GT3 is much more stiffly sprung than the base and S 991s.
DRP
#40
07-16-2012 | 01:29 PM
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^^^ , I do recall many reviewers saying that this new suspension set up is what makes the MP get better lap times then a 458 in most cases. The 458 steering is so great because there is only 2 turns to lock, whereas most other cars require 2.75 turns to lock. The MP does have less lean then the 458 and a more compliant ride. The complaint that some reviewers have is that it is not as fun because it is engineered to not have any over or under steer, even with traction control turned off. It is also very hard to turn traction control off on it. The engineers say why would anyone want to turn it off. So it is usually considered less fun then a 458.
#41
07-16-2012 | 02:21 PM
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No way I would buy a 991 without it!!! The car gives plenty of warning. Anyone that says otherwise is full of B.S. At least with traction control on, you can get all 4 tires sliding just a little without worry. I had the rear come out on me a little bit once in a high speed corner, and it was very easy to control as well. The lack of body roll without having to have a harsh suspension on the bumps is the best of both worlds!!
Last edited by rdalcanto; 07-16-2012 at 02:23 PM.
#42
07-16-2012 | 02:55 PM
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The new issue of Excellence reviews the 991S with PDCC. I don't see it on the website but read it in the print edition.
Overall the review is pretty favorable, but the PDCC gets a bad review for "killing the buzz." Reviewer says its no fun not feeling the G-forces as a driver and doing the side to side "dance" in S-turns. To be sure, that's not a performance critique (and the reviewer says he'd opt for a manual for largely the same reasons), but owning a PDCC 991S, I know where he's coming from. I do sometimes miss that feeling too.
Re ^^^^^, I think PDCC is less important on a SPASM car because the center of gravity is lower, but for me that wasn't an option because I drive too much on public roads that would make mince meat of the front end on a lowered car.
Overall the review is pretty favorable, but the PDCC gets a bad review for "killing the buzz." Reviewer says its no fun not feeling the G-forces as a driver and doing the side to side "dance" in S-turns. To be sure, that's not a performance critique (and the reviewer says he'd opt for a manual for largely the same reasons), but owning a PDCC 991S, I know where he's coming from. I do sometimes miss that feeling too.
Re ^^^^^, I think PDCC is less important on a SPASM car because the center of gravity is lower, but for me that wasn't an option because I drive too much on public roads that would make mince meat of the front end on a lowered car.
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