s4008616

I have a 991.1 Carrare S.

I hate the idea of raising the wing during normal street driving, so I never put it up to disrupt the beautiful 911 curve.

However if I am doing track day, should I leave it up all the time or just it in auto and let it raise by itself when reaching 120Km/h?

Would leaving it up all time increase my lap time?

LexVan

Leave in auto mode.

The wing is very dynamic, and reacts very fast. This past summer, I was watching a lot of 991's driven at Road America. I watched a lot of action in turn #5. For those not too familiar with this track and corner, it's a low speed, very hard left hand turn going uphill at track out into #6. Before the braking zone, a 991 can easily be into the 120's. The fastest you can be at the apex is in the mid 50's.

Sure enough, 991's into the braking zone are wing up. By apex the wing is down. At track out, accelerating up the hill into turn #6 the wing is up already. Pretty impressive.

s4008616

Thanks for your reply. I have been leaving it in auto on the track too.

It was just because I have read a lot of posts discussing the dual personality of 991, and people are saying 'wing up and the car was good to go on track'. Sounding like they leave it up full time on track and therefore my question.

drcollie

If you put on a wing or spoiler on a street car at the track, it will reduce your lap time due to the aerodynamic drag on the straightways. typically it costs you 3 to 5 mph on a long straight. They do NOT make you go faster. What the pop up spoiler on the Porsche (and other cars) does is stabilize the car at speed to prevent rear end lift that can make the car crash in a high speed turn. in the first generation Audi TT's there were five fatalities due to this 'trailing throttle lift oversteer' effect, and Audi cured that with the addition of an automatic rear spoiler deployment. Porsche had it much earlier - my 1996 C4S had it. But it was the Audi TT fiasco that made these mainstream.

If you put a real wing on a car (not that little pop up thangie) AND a front splitter AND racing tires - either slicks or R Comps. AND a super stiff race suspension AND lower the car then you will see a marked improvement in cornering speed and can trade that off easily for the slower straightway loss. But in a street car with regular tires, regular suspension, etc. you cannot take advantage of the Aerodynamics that a wing and splitter will give you.

So as LexVan says, just leave it be and (I will add) if you want to improve your lap times, learn braking technique. You can gain far more in braking technique than you ever will with wings/spoilers.

rye595

Leave it up. Helps a little with cooling, provides downforce, and I worry about the actuator failing after constant up down up down on the track. The 997 wings used to fail after a while.

Need4S

DrCollie I'm sure means your lap times will INCREASE not decrease due to the extra drag (slower car=longer lap times). I would leave my spoilers deployed on the track rather than have them go up and down. Main reason is to avoid excessive ups and downs that cause wear on the mechanism. If I lose a few mph down the straights, it doesn't matter, as I'm not racing, and I'd rather have a bit more stability all the time rather than optimize drag for the straights. On the road, I leave it in auto, since I don't want to have to replace expensive air bladders on the front spoiler due to road hazards, speed bumps, etc.

s4008616

I guess the conclusion is

Auto wing - if you are chasing the best possible lap time

Wing always up - to reduce wear and tear of the actuator

drcollie

delete

997s07

Well said. Racing dynamics is very complicated. The reason race cars have no low end torque but huge high end HP ("torques" per RPM) is to balance the drag at speed. Now, make the car light, and it can accelerate hard at low speeds and low (though through gearing usually not) RPM.

Tcc1999

You're not getting much, if any, significant down force from the standard wing - I am pretty sure that was not the intention of the engineers. The standard wing has the dual purpose, of aiding in engine cooling and, perhaps only important at speed, for aerodynamic (not down force) purposes. The three basic aerodynamic forces are thrust, drag and lift. It is lift that the standard wing is intended to counter. Because the 911 is not a airplane (yet) it is really only the Bernoulli Principle that is of consequence, well at least the most pertinent (and not Newtons 3rd law or the Conada Effect). The Bernoulli Principle basically concerns airflow over an object with a flat bottom and curved top - specifically, the pressure of a moving gas (air) decreases as velocity increases. Now take air flowing over your 911 with a flat lower surface and a curved upper surface. The flow is faster over the curved surface and this creates an upward pressure - Lift. The small wing on the 911 is intended to ever-so-slightly disrupt the airflow over the curved upper surface and, in so doing, slows down/disrupts the airflow. With the airflow disrupted lift will decrease and the 911 should be more stable (less light feeling) at higher speeds. So, in the end, in the absence of a gignormous fixed wing, you want the wing to be raising and lowering - but, since it doesn't have much impact on overall drag particularly at lower speeds, having it up all the time wouldn't hurt lap times.

Larry Cable

+1

Yellow996

Agree. Plus, on hot DE days it helps with engine cooling. When I had a 997s, I had issues with the actuator. It must be less wear and tear if it's up for track days.

By the way, if you keep it up for more than 4 hours, please consult your physician.