Fishdoc

Dont worry I have not and have no intention of driving max speed these cars are claimed to go. However......
An interesting thread on Gt3 forum on claiming to drive Gt3 200 mph.
My question is Is our turbo's more or less stable at top speed vs the Gt3?

Obviously too much time on my hands.
Maybe no one here has tested such limits.

floridaBMW

I would imagine being "stable" at top speed in any street car is not likely. Clarkson reached 200mph on the Autobahn in a 997 Turbo, so obviously it can be done under right circumstances. But IMO "top speed" is the limit of the car, they arent built to sustain these kinds of speeds.

Ken

Macster

Hogwash. If any car is designed for sustained high speed driving it is a Porsche.

There are plenty of owners not to mention the number of car mag car testers who can and do drive at V-max or close to it for long enough periods that if these cars had any weakness in this area we'd all know about it.

I've had my Boxster at high speed for miles and miles in a very deserted/empty area of the USA in very hot weather and the car suffered not one whit from the experience. My Turbo has been driven even faster though for not as long but in equally high temps with no problems.

OTOH, by way of an example I recall years ago on a
Ford Mustang forum -- when I owned and drove a Ford Mustang GT ('96 model) a Ford Mustang owner in Germany after taking his automatic equipped Mustang out for a high speed run reporting the transmission acting up. The word he got from Ford was the car was never intended to drive at those speeds for any length of time.

I would if it were legal gladly and without any fear of any engine (or other car trouble) drive either one of my Porsches as fast as the road and other conditions would allow without any concerns about the car not being designed for this sustained high speed driving.

There is something of a limiter though on how many miles one can drive one of these cars at high speed, speed approaching or even at V-max, and that is the range of the car when gasoline consumption goes up to very high levels when running nearly flat out.

Sincerely,

Macster.

CaioLLV

I just drove a SWITZER P750 997TT and that is fast!

NoPasaran

I have Mk1 manual Turbo with 572hp and lowered with H&R springs, 245 and 325 tyres. I went on German Autobahn. All I can say is when I hit 260kmh I did not want to go faster, too unpleasant, the front is very light and the steering is light and twitchy. I did 300kmh in my previous Audi TT RS, that was a pleasure to drive fast.

mm450exc

+1 Did 270km/h and that felt really fast!

phillipj

Do you think it might have something to do with your car being lowered? A lowered car may behave differently than then stock at very high speeds.. I went 175 mph in my car with stock suspension and springs and the car was very stable.

I have not had my car up to anything above 120 mph since I installed the H & R springs... felt good at 120....

floridaBMW

I absolutely agree with you, Porsche cars are very capable of v-max/high speed runs and for certain lengths of time.

My concern continues to be whether the car can continue to be stable over longer runs. I imagine the aero pkg on Porsche cars is some of the best in the biz. But wonder if its set for this type of driving. Again, its just my personal, very limited experience and opinion.

Ken

TT-911

Some years ago I drove home from Basel (CH) and felt like going fast.
So I drove flat out wherever I could for the complete trip (over 5 hours) . Reached 300 km/h and more several times and car felt very stable ! That trip I'll never forget. It turned out to be very unique and am glad I was able to do it.

speed21

245/345 tyres indicate you have 20" rims? I hear from reliable source 20" on a Turbo really screws up the handling/driving behaviour. Best to stay on 19" and retain handling. I'm sure 997TT has been driven at vmax by Porsche testers before being released....

TB993tt

He says 325 tyres so still likely 19"

The 997 turbo has a nice areo balance, see below, translates into a bit of lift at the front and some downforce at the back:



I extrapolated the lift numbers and you can see the 20kg lift at 200mph is such a small number it will not affect the stability, similarly the rear downforce @ 30kg is pretty insignificant, the car is nicely balanced at speed.


The important things to check for very high speed are tyre pressures and suspension geometry.
In any 911, Going over 250kph(155mph) GPS for the first time is scary, going over 270kph is very scary, breaching 300kph 186mph is terrifying but here's the amazing thing, do it 10 times in a row and by the 5th time it is not so scary and by time 10 it's no sweat at all. Next you go over 320kph 200mph and it is just as scary as the first time to 300kph.....

What should give you some confidence is knowing the fastest street legal car in the world is the 997 turbo prepared by Alzen which hit 400kph 248mph using a 1050PS 3.9 litre Mezger engine
http://juergen-alzen-motorsport.de/m...wagen-verkauf/

Fishdoc

Thanks TB for test results.
Prob wont be hitting the 200mph mark anytime soon.
frank

NoPasaran

Yes, I have 20" HRE P43 rims. I am not going to replace them with 19s.
Many tuners put 20s on 911 Turbo, I do not think 20" do anything to handling, why would they?
There is lift on the front at high speed, maybe with bigger tyres the lift is even higher?

NoPasaran

I think I will have to do some more high-speed runs, I've only done one so far.
Though must say the first high-speed run in an Audi, where I breached 300kph in winter on winter tyres (255/19 all around) was less scary than driving 997TT 260kmh in summer on bigger tyres (245/20, 325/20).

What about those 1500hp Gallardos and 1200hp GT-Rs? I thought they were the fastest street legal cars (until 1500hp Aventador comes out).

rrm

In 1980 during a brain seizure I traded my '67 "3duced" 427 vett in for a brand new White 928. First Porsche I ever owned. I was tired of having to look for a hill on the top of which to park my vett. The 11.5 compression ratio would not be started by a mere battery. I needed gravity to help and as I lived in Houston at the time, hills were in short supply.
I had the Porsche for a couple of months when my girl friend and I decided to take a road trip the ski in Breckenridge. There is a patch of road between Ratton NM and Texline Texas that I was sure was named "Please drive crazy fast" Lane. I could never turn such an offer down and proceeded to see if I could remove the windshield wipers by sheer wind alone. I really didn't go that fast but did try to keep the v8 (thats what they told me it was) humming at between 120 and 130mph. After about 50 miles of this the car started to "miss". "Miss" is the only word I can think of to describe the jerky action. I thought that perhaps it wanted to go faster but soon learned that was definitely NOT what it was trying to communicate. Two weeks later my girl and I took the car for what was supposed to be a short weekend trip to Mexico. At the end of that trip I found myself as the proud owner of not one but 2 928's tho to be fair one was a 928s....but that's another story.
I never tried going past 120 or so until I purchased a ZO6. There is a nice little FM road that is a short cut between Corpus Christi and the major hiwy that takes one to the RG Valley. It is straight and flat but only two lanes that seemed to shrink in relationship to the speed. I was doing OK until about 140 when a godauful bang rips thru the car followed by what I can only guess would be what a wind tunnel would sound like. What had happened was that the rubber insulation between the drivers window and side of the car had been sucked out of it's intended position thus creating the banshee like scream. That taught me to stick to try to being the king of the 0-100 crowd....rrm