Cole

I've seen reference to the number in a couple of places.

One that was easy to find was in the Cayenne book page 52.


I would probably have to stumble on the other source to quote it. I know there was one that had numbers for the 911 and the Cayenne, just can't remember where right now.

The whole point was also that stopping power should not really be that much of a limiting factor for track use.

From insideline's tests.

60-0 in the Cayenne 116ft
60-0 in 011 Carerra 4 105ft.

http://www.insideline.com/porsche/ca...e-cayenne.html
http://www.insideline.com/porsche/91...carrera-4.html

Cole

Which you can see a neat test between the new ones here.

http://www.youtube.com/watch?v=QYZart5XXUo

ltc

I can see no way of any production Porsche achieving 10g deceleration...under any circumstances.

Here is a simple deceleration calculator
http://www.measurespeed.com/deceleration-calculator.php
Enter 60mph start, 0 mph stop and 1 second (assuming any production car can go from 60 - 0 in 1.0 seconds)... 2.73g's
(remember, the Bugatti Veyron holds the record at 1.3g's deceleration; 60 to 0 at 1.3g's would be 2.1 seconds)

In order to get 10.9g's deceleration (per your quote from the Cayenne owner's manual), you would have to go from 60 to 0 in 0.25 seconds.

Do you really think that is physically possible?
Do you think a single 3 point harness would hold you in your seat at 10g deceleration?

Would you please reconsider and reclarify your previous statements:
The figure achieved for a full brake application is in the region of 10.8g, in other words up to Porsche's usual high safety standards
The turbo and S brakes were designed to provide almost 12g of braking force, the same as the 911

Disclaimer: the statements above are in no way meant to "bash" the Cayenne and are based strictly on the laws of physics, posted on behalf of Sir Isaac Newton.

Cole

Once again you read into it what you want.

I never said 10g of deceleration. I said 10g of braking force. No idea how they get this number. Sounds like it is a measure of the brakes ability to reduce the speed of a given mass, probably on some sort of brake dyno, not it's actually stopping g's force in a given car with certain tires on a certain road surface, etc.

Neither of which matters at all in this thread anyway, since the point was that in whatever form they were using the number, it was used to compare it to the same number on the 911.

Bottom line.....The Cayenne brakes should not be " hopeless on the street" as evomotion put it.

ltc

Braking force, as in Force = Mass * Acceleration (or Mass * Deceleration if you prefer)?

It is generally not a good idea to post something about which you have no idea, as it makes further discussion a bit difficult, don't you agree?

The ability to reduce the speed at which a mass is traveling sure sounds like braking.

Again, no bashing, implied or othewise, just trying to understand the previously posted information.

Cole

You are still missing the whole point, nit picking and trolling. Yippee!!!

Did you actually have something Cayenne related or Cayenne track related in all of this?

Or are just just trying to destroy yet another thread in the Cayenne forum by derailing the discussion away from the actual point?

ltc

None of the above.

If, for example, you were in the Racing/DE forum and mentioned that a Cayenne (or any other vehicle) can brake with 10.9g's, you would likely receive the same amount of questions.

I was merely trying to understand what was obviously a physical impossibility.

Would you have the same reaction if I posted "a Cayenne Turbo S can accelerate from 0-60 in 1.9 seconds, and then when questioned, I had to say, well it's 60 something, perhaps feet, I'm not really sure, I read it somewhere" ?

If you consider that nit picking or trollling, then I don't know what to say.
I realize that I have no Cayenne experience nor track/racing experience.

Cole

Then why not focus on the actual source of the number, which I gave you.

Try to figure out how they calculated it instead of trying to spin a side line number into arguement material?

Focusing your arguement at me is a bit silly since I'm not the one that actually calculated the number. I pointed you to the source. That would be like someone saying "I have a 450 HP Cayenne" and then showing you the brocher. Then you beating them up about how the number is calculated.

It would be one thing if the number were being used as the point itself, which it wasn't. But if you are so curious about it, try to figure out how they come up with that number. I have seen it in multiple places and will at some point try to track down the other one.


Now, if you want to talk about braking and the Cayenne as a track vehicle and apply some math to it then we should look at ways to make it stop better. For example, the differences in clamping force or ability to shed heat of the Turbo/S calipers compared to the "Turbo S" calipers, larger discs etc. Best track day pads, slotted/drilled rotors etc.

pdxjim

If they were talking military aircraft in the manual, I could understand. But, for them to be talking Cayenne in the same breath, somewhat confusing. Will have to check out my manual when I get home!

Cole

This book.

http://www.amazon.com/Porsche-Cayenn.../dp/0760314527


Not the owners manual.

Renn 951

Just goes to show you can't believe everything you read in a book; or even everything you read on the internet for that matter!

Most likely they misplaced the decimal point and meant to say that the braking force was 1.09 G.

Van1

Not a Cayenne but I did track my '07 Touareg V10 TDI a year and a half ago at a BMW event. I posted these pics before in another thread but here they are again. It was a fun time and I don't think I could have gotten more attention that weekend if I had driven a Lambo to the event. I was not the slowest car in the advanced group. When it rained on Sunday, I was lapping the M3's as my pace never slowed. My limfac was the whole weekend was the Goodyear Fortera highway all season tires. Some summer tires would have been nice. Except the Forturas did work well in the rain.

Coochas

I was a passenger in a Cayenne Turbo at Barber with a PSDS instructor driving taking 3 passengers. It's pretty impressive but as he said, "it's just a drag race between corners." They say that they can keep up with another instructor driving a base Carrera but after a few laps the Cayenne's brakes go.

LastMezger

Yup. Wrote about it here:

https://rennlist.com/forums/porsche-...o-is-fast.html

Here are the shots from the other thread. A little tail wag and some three-wheelin'. The vehicle is simply unbelievable on track.

cab&coupe

Like a track friend/instructor of mine once told me one day while at the track... "the laws of physics are just that... they're laws... not suggestions."