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Board: Porsche - Cayenne
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Oct 13, 2003 7:56:46 AM
- Jeffrey Behr
- Junior
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- Loc: Phoenix, AZ USA
- Posts: 129, Gallery
- Registered on: May 17, 2003
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Reply to:
RC
...which equals 150mph...
...which is what I acheived in my Turbo on a long, very straight and open country road in California last month, with 2 passengers and luggage in it, going slightly uphill. It was still accelerating; we just ran out of room. Next time, DOWNhill!
The speedo indicated 142mph, with tires that are 5% larger in diameter. The speedometer calibration (that is, 5-1/2% slow) was verified with a GPS receiver.
And RC, based on my universe of one Cayenne, I'd say the speedometers are pretty accurate with stock tires.
The speedo indicated 142mph, with tires that are 5% larger in diameter. The speedometer calibration (that is, 5-1/2% slow) was verified with a GPS receiver.
And RC, based on my universe of one Cayenne, I'd say the speedometers are pretty accurate with stock tires.
Oct 13, 2003 8:07:31 AM
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RC
- Rennteam Administrator
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- Loc: Rennteam HQ , Germany
- Posts: 59607, Gallery
- Registered on: Mar 26, 2002
- Reply to: Jeffrey Behr
Re: ...which equals 150mph...
Quote:
...which is what I acheived in my Turbo on a long, very straight and open country road in California last month, with 2 passengers and luggage in it, going slightly uphill. It was still accelerating; we just ran out of room. Next time, DOWNhill!
The speedo indicated 142mph, with tires that are 5% larger in diameter. The speedometer calibration (that is, 5-1/2% slow) was verified with a GPS receiver.
And RC, based on my universe of one Cayenne, I'd say the speedometers are pretty accurate with stock tires.
Jeffrey, we did speedo testing on the Turbo using a calibrated(!) GPS unit and at top speed (281 kph) the "true" speed was 268 kph.
I don't know ANY Porsche speedo to be accurate at top speed, most have an error of around 12-16 kph.
BTW: german AMS magazine always tests speedo accuracy too, there has never been a Porsche to have a 100% accurate speedo. At 200 kph, the true speed was always around 6-8 kph slower.
Re: ...which equals 150mph...
Quote:
anyways no problem with this speed straight forward but in the first light curve you p..s in your pants - not a good feeling, telling you :-)
Ever drove a ML55 through a pretty narrow Autobahn curve at 250 kph speedo speed? I can tell you that this was the most scary moment in my life and I'll never do it again. The pavement was a little bit bumpy, the ML55 started shaking, the steering is very indirect and I was almost sure that I'll loose control. The problem of the ML55 is the pretty stiff suspension gives a very trustful feeling but the steering takes away a lot of that trust. I've been told that DC made that steering setup that way so that drivers aren't able to turn the steering wheel too fast which would increase the risk of a rollover. It is true that it is a very "safe" setup but it is like a pain in the a.. when you try to go fast through curves.
BTW: I don't know about the S but the Cayenne Turbo did pretty well in fast Autobahn curves, even at top speed.
Re: ...which equals 150mph...
>BTW: I don't know about the S but the Cayenne Turbo did pretty well in fast Autobahn curves, even at top speed. <
maybe - the turbo have air suspension and I steel and 20"ies. The bad feeling in the high speed curves been near simular when i top speed the SL 500 in comfy mode - when you switch the SL`s air susp. to sport its much better and you feel safe. Beside this you feel this 2.3 tons badly pulling the cayenne to the armcos...
maybe - the turbo have air suspension and I steel and 20"ies. The bad feeling in the high speed curves been near simular when i top speed the SL 500 in comfy mode - when you switch the SL`s air susp. to sport its much better and you feel safe. Beside this you feel this 2.3 tons badly pulling the cayenne to the armcos...
Oct 15, 2003 1:42:43 AM
- Jeffrey Behr
- Junior
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- Loc: Phoenix, AZ USA
- Posts: 129, Gallery
- Registered on: May 17, 2003
- Reply to: TATARIN
TATARIN, yes--a change in tire diameter directly...
...affects speedometer readings. Speedos are driven, usually, by the transmission output shaft (AKA driveshaft), but even if they're driven by wheel-speed sensors (as I believe they are in the C), tire diameter makes a difference. For a given tire-rotation speed, the greater the tire diameter, the greater the vehicle speed. So very tall tires make the vehicle MUCH faster than the speedometer reading. Conversely, tires much smaller in diameter, as the ethnic groups in this country seem to love using, cause the speedo to read higher than the vehicle is traveling.
Based on my Cayenne universe of one, I'd say the speedo is more accurate than that of any other vehicle I've seen. When my tires grew 5% in diameter, the speedo became 5-1/2% slow.
Based on my Cayenne universe of one, I'd say the speedo is more accurate than that of any other vehicle I've seen. When my tires grew 5% in diameter, the speedo became 5-1/2% slow.
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