WOTever

I'm still exploring the limits of my stock X50 when driving on the road (before people get worked up: when no one is around) and I have noticed the following:
The car understeers quite a bit when cornering with neutral load.
Trail braking massively reduces the understeer.
When I hammer the trottle in a turn, the car drifts very slightly with some rear bias.
Everything feels very composed and balanced with PSM on, I never get the feeling that I'm about to dissappear in the ditch.
I need to find a track in the Houston area to properly find the limit but in the meantime I'd like to hear your experiences with the stock setup. Have you ever spun your 996tt on dry surface with PSM on?

T10Chris

Even on a wet skidpad going full throttle in 1st gear with the wheel turned I couldn't spin mine with PSM on; this doesn't mean it isn't impossible, but I think if I was going out of my way trying to spin it and couldn't that it is going to be pretty hard to do as long as you are on the road and being attentive to your driving.

Anything is possible though. Im sure someone on here has done it somehow, there are many variables to every situation...

Dock

There are public road curves in the Houston area?

WOTever

True, most turns around here are right angles but there is also
Www.motorcycleroads.com
Better than nothing...

Third-Reef

Basically you cannot spin your car with the PSM on using the throttle. However carry too much speed into a corner and it will spin for sure.

Atrox

911mhawk

It's wet leafy road season around here. Fast down a sunny straight into a cold shady corner will always be a bad idea. Mechanical grip seems to be what many forget about driving newer cars too. Eventually you will just run out of grip if you're testing the limit.

Carlo_Carrera

First off you should not be driving anywhere near "the limit" on the street even if no one else is around. You are still around and if you stuff or roll your car and damage your brain or kill yourself your poor relatives will be stuck taking care of or burying your sorry self. Buy a helmet, HANS and belts and go to a racetrack. You will learn more about your car's handling in ten laps than entire year of "on limit" street driving.

In answer to your question I have spun my TT in every way possible on dry race tracks. PSM is a great safety device but not absolutely fool proof and I am a track driving fool. Basically if you get the car unbalanced by too much steering angle or too much throttle, brakes or speed it will spin.

Carlo_Carrera

Not true, try getting on the throttle a little too much a little too soon in a hill crest corner. PSM or no PSM you will go right around.

Jferrante

When I first started tracking I would leave PSM on and too fast and too twitchy into a series of turns will easily spin this car with PSM on

Third-Reef

I stand corrected. I agree you can spin your car with the PSM on in extenuating circumstances, like un-weighting on a crest, unexpected loss of mechanical grip and or too much speed. I was referring to just nailing the gas and pulling a C and C mustang move, it does a pretty good job of holding it back and keeping it straight. Way better than a corvette. Find a wet parking lot and "test it". I was surprised at the high level of grip in the wet compared to any of my other sports cars i have owned.

996tnz

Almost all my driving has been with PSM disabled as it normally excuses itself after the first corner (fails out fully, including under braking). So unless launching in race, I don't even bother pushing the PSM off button as the car does it better. But one time PSM stayed on for a lap or two at a track day and it caught me by surprise entering a high speed falling right-hander coming off the main straight. I went in as hot as I normally do and the car just refused to trail brake in heavily and take a set, just sledging wide instead. A dab of gas to help it point back in tighter was also stomped on by the PSM, leaving me a near helpless passenger watching the edge of the track get closer while I waited for the car to hand me back some reasonable level of control.

So while spins are possible with PSM, rather than 'spin for sure' I think with PSM active it is more likely to be ''sledge off road for sure' if going and turning 'too fast' for PSM's liking?

Any more details or noticeable pattern in those spins Carlo? Like you, I keep my spins to the track and basically just consider it to be the car's way of telling me I'm doing it wrong. I'm interested to know how those PSM enabled spins differ from the car's raw behavior. As mentioned above, I almost never drive with any functional PSM but maybe for others tracking or racing their 'AWD' 911s - and perhaps unplugging PSM while doing so - a few shared expreriences might be useful. Bear in mind these are over a 5 year period, mostly early on:

1st time - Dry - First time club racing and I listened to my competitor's advice to drop my (road) tyre pressures down to the low 30s. Between that and running out fuel mid-corner I spun her 90 and stopped mid-corner.

2nd time - Dry - First track day and I had too much attention on the GT3 in my rearview mirror instead of the sweeper ahead. Entered it 10 odd MPH too hot and had little choice but to brake and trailbrake much heavier than usual. The rear stepped out fast so I gave a good dose of gas and countersteered to try and catch it. Drifted the sweeper nicely (luck not skill - first time I'd drifted her) and the guy behind later told me he thought I'd make it right around and back out the other side. But I couldn't tighten her line enough and needed to do something else before drifting off track near the track out point. So figuring she was AWD I added more gas and countersteered more to have the fronts pull her straighter. But 996T AWD is not Audi Quattro AWD, so all it did was light up the rears and finish the process of swapping ends. As she came through 90 degrees I threw her in neutral and applied brakes, modulating them again as she came through 180. She kept rotating and ended up near the inside of the track at the exit of the sweeper.

3rd time - Wet track day, and some spilt oil had been cleaned off the track just before our run. And chasing a more experienced driver in his modded 996T on R-comps. Rolled on the gas a little too early rounding the slick sweeper and the back came out. A reflexive twitch of steering relaxation and smidge of gas didn't bring her back into line, so a bigger dose of opposite lock and gas was given. That caught her, but I overcorrected and didn't damp down the fishtailing so ended up spinning and finishing on the inside again as per above. Had in car video running:
http://www.dailymotion.com/video/x2odu8w_walt-996-turbo-wet-spin-hampton-downs-t10-28-4-2015_auto
4th (near) time - Super wet track day (aquaplaning a section of the main straight each lap at one point) and I stayed out on track after everyone else had gone in (love the rain!). Apexing out of the esses that fed the start-finish straight I was running the kerb but the thick mastic markings for the starting grid probably also contributed to her rear coming loose on me.
Stepped out big time and a big catch was needed with instant countersteer and a touch more gas. others in the nearby pits were unsighted by the pit wall but heard the squealing of tires. They expected a crunch (another car had been totalled that day) but I caught it with a moderatley messy fishtail and carried on lapping. No video but the AIM's G traces looked pretty dramatic.

5th time - There hasn't been a fifth time, but that's not saying there won't be of course. I did learn from the above spin though that in an adrenalin-fueled emergency I am likely to overcook my inputs. So I have since sort of 'preloaded' and visualised tapering my inputs down as I recover the car. Obviously what the car is actually doing will still inform my responses in real time, but that tapering is now kind of the underlying 'base map'. At the most recent Porsche Club sprints, on coldish tires (lap 1) with a competitor breathing down my neck I was a bit greedy exiting the hairpin and she broke loose but I caught her this time while applying that tapering of inputs:

http://www.dailymotion.com/video/x40ackh_porsche-turbo-fishtail-save-nzfmr-2016-porsche-sprints-race3-lap1_auto
Not sure how much that helps the OP understand what happens in a spin with PSM on, but it's all I can offer. I'm sure there are plenty of others here with more extensive experience and better technique, so will watch and hope to learn more.

Note that if in doubt 'in a spin, both feet in' (for a manual) is still the best advice most of the time, but its pro is also its con - ie you will continue to travel in the same direction you're headed in, while slowing at about half to two-thirds of your car's normal limit/ABS braking rate.

Carlo_Carrera

All I will admit to is that I occasionally attempt to defy the laws of physics. And because I'm a bit dense sometimes I will try it twice just to be sure

T10Chris

I can see this happening... Carry too much speed, PSM doesn't like what you're doing on entry and it helps you plow right off track/corner/road/etc.

"02996ttx50

"While confident in the system’s ability as a dynamic handling aid, Porsche cautions drivers that PSM cannot counteract the laws of physics" - Porsche AG