High speed

[Henrik68]

Hi

I bought my first 997 C2S and of course I have to try to throttle up a bit. My feeling when the car comes up to over 270km/h (170mph), the nose feels very light and almost a bit unstable. I have done a wheel alignment. The wheels are great and N labeled. I am a beginner in fast cars.

I am curious how you experience your cars at high speeds?

[White987S]

Never been that fast on the track. My cars are rock solid. Be careful out there.

[Uwon]

Hej Henrik, Ahh... the thrill of 270 kph.There are many potential reasons why you may experience front end lift. Did you set the wheel alignment to standard Porsche or more aggressively (a must)? Consider changing the rear uppers to something more solid-seem to eliminate the rear end jerking which sometimes gets mistaken for front end lift. My own experience sitting in the passanger seat as a PCA instructor and in my own cars is that most unmodified rear engined Porsches will be somewhat unstable at 270kph (GT3 excepted) which we can readily hit on the the back straight at Mosport, if you have enough power, balls and skill. Also experiment with tire pressures and consider installing a front end splitter. You can make one yourself out of aluminum. Hope this helps. Good luck. Cheers from a fellow Swede living in Canada.

[brendel]

Hi there, I reached 275KPH on the Autobahn, I felt I approached top speed

What an engine noise!!!vibrations and wind noise, it seems to me that the car knew it was on the autobahn, like it was kind of happy :thumbup: the throttle seemed very responsive, I felt like I was driving another car and for once seeing what its potential was

Yes you do get a feeling that the steering gets lighter, I also felt what Uwon described that the rear seems to be jerking around ( engine mounts?)

Another feeling is that the brakes are very soft and I really wonder how quick you can stop the car at that speed, I then understood why they sell all these big brake upgrades

Take care

[Henrik68]

Thanks all for the quick response!

According to my mechanic so is wheel alignment between road and aggressive. The tire pressure is standard. The car is equipped with PASM (Sport mode) but have no "lowering kit".

The car is also used to go to work so an aluminum front splitter, don´t i think will work.

Do you think it would help to install stiffer/lower springs in the car?

Is there any "attractive" front spoiler that can almost replace a splitter?

High speed requires good brakes! I have replaced my old against new OEM. I agree the car makes a lot of noise in that speed !!

High speed saves time .....

[White987S]

Just a thought, are you sure your rear spoiler is deploying at speed (72 MPH-ish)? This could cause some high speed instability.

A car with PASM is already 10mm lower than a non-PASM (USA spec) car.

[Henrik68]

The rear spoiler is working.

I looked around the net and found something called Sway Bar! Do you think that can help?

[Uwon]

Henrik, before we go any further, perhaps you could tell us where you are driving at 270 kph-windy road, straight road or high speed track or track? Big difference for tire pressure settings. Also, what tires are you on?

[Henrik68]

The speed is tested on a big fine high way near Stockholm capital of Sweden. It's pretty straight! "unwindy" nice new asphalt, almost like autobahn

Michelin Pilot Sport 295 30 19 N2 100Y rear

Tire pressurer is according to the label but upper level.

This is not a big problem i was most curious about other experienced their cars!

[phillipj]

I'm not an expert and certainly not a driving instructor. That being said (apart from what has already been discussed) an Aero kit kit would be a real help. A Gt3 front bumper cover and rear wing would make the car much more stable at the speeds you are speaking of. Also I believe that lowering the car would help as well. (it certainly helped my turbo) Other members please chime in if I'm wrong about this..

Edited November 6, 2012 by phillipj

[michelin]

Hi Hennrik

I had the exact same issue to yourself. It has now been solved.

1. Make sure all of your tyres are the same make. Porsche are very fussy when it comes to tyres. In the manual it says to always have the same manufacturer on all 4 wheels.

2. Make sure your front splitter is intact and present.

3. Finally get a quality wheel alignment carried out on the car. I use a place here in the Uk called Center Gravity. They are excellent. Have a look at their website to get an appreciation of what you should be aiming for.

Cheers

Peter

[Henrik68]

Hi Peter

I have Michelin Pilot Sport on all 4

The splitter ...!? Is it the small rubber lip under the front you think of?

Hmm maybe i have to do the alignment again ... Will read the web page first

Thanks allot

[dphatch]

Henrik68 you're living on the edge, and I cleaned that up for the forum police, driving an unsorted car at that speed on a public highway. Hope you alert your friends before you get out on the public road again so they can steer clear.... Lose control at that speed and they don't send out an ambulance, just the guys with shovels to clean up the mess.

After you have had a chance to have the car set up properly for high speed driving, maybe you'll find a proper race track to test your skills on .

[Uwon]

+1

[Dus10R]

Welcome to 911's... Very aerodynamic, but also very low positive down-force unless you add aerokit or own a GT3 or RS.

Its normal for the front to feel light at high speed. They are zero lift, but like I said, very little down force to be had stock.

Had my old Turbo at 200 MPH and very small gusts of wind made the front feel like it was going to lift off the ground. Can be unnerving if you are used to cars that make downforce. I had an old Mits Evo VIII, that at 170 MPH felt way more stable than my Porsche, and its because it made gobs of positive downforce. If you lower the car, that will help too, but in reality there's nothing wrong with it, you just have to get used to the float feel. Hence why Porsche's have always had high top speeds with very small amounts of power, lite weight, neutral aerodynamic down force with low drag.

Now as far as driving fast goes...people in the US have this mental catch with any speed over 100 MPH. We drive so slow in this country that people hear the century number and think pending doom. Drive in Germany for awhile and you realize that speed is very relative. You get past by station wagons on the unlimited sections of the Autobahn if you're not driving 120 mph. And once you have been at those speeds for awhile, you slow down to 75 or 80 and it feels like your crawling, like you could open the door and step out. You'll also notice that German cars usually have different tire pressure recommendations for anything over 100mph, its because people drive them that way in Europe frequently. Now that being said, it also takes them many years and many dollars to get their drivers license that allows them to drive on the Autobahn. They actually learn how to drive, as opposed to here where kids learn the rules of the road instead of vehicle dynamics. Driving fast isn't inherently dangerous up to a point, in fact its been proven that people tend to concentrate more on driving when driving fast. But everyone has different comfort zones. Ive been at 130 mph for over an hour and it eventually feels just like it does at 70. For me personally, it starts to feel fast north of 155 mph, and between 175 to 200 it feels very fast. Now in a Buggati it may not. But speed is relative and if you're trucking along at 100 plus but everybody else is doing 70 then, yeah, you're asking for problems. But if everybody is going those speeds or if you are alone and nobody else is around then its your own comfort zone that should dictate what's safe.

Edited December 6, 2012 by Dus10R

[White987S]

Had my old Turbo at 200 MPH

Really? Nice! Couldn't have been stock. What mods? Chip and turbo?

[Dus10R]

Had my old Turbo at 200 MPH

Really? Nice! Couldn't have been stock. What mods? Chip and turbo?

Before mods, 198 mph. After mods, 205 mph (with mirrors folded in)

Mods were many... Turbos, y-pipe, intake, boost controller, fuel pump, fuel injectors, map, strapped plenum, headers, muffler-less exhaust, upgraded cooling, lowered, super light wheels, high octane fuel,etc etc...

[White987S]

Had my old Turbo at 200 MPH

Really? Nice! Couldn't have been stock. What mods? Chip and turbo?

Before mods, 198 mph. After mods, 205 mph (with mirrors folded in)

Mods were many... Turbos, y-pipe, intake, boost controller, fuel pump, fuel injectors, map, strapped plenum, headers, muffler-less exhaust, upgraded cooling, lowered, super light wheels, high octane fuel,etc etc...

198 MPH Stock? Really 996TT ....997TT? Confirmed by the speedo or GPS (Garmin)??

Did not think a stock TT was capable of this speed.