Autocross tips
 

It has been several years since my last autocross and it will my first with the C2S this weekend. A few questions:

PSM on/off? I've read off is the way to go for autox so that throttle is not cut too early

PASM normal/sport? I don't think sport is often recommended unless the surface is really flat?

I also heard the stock setup tends to understeer. Are there any other things you guys can think of?

at first AX you will have an instructor - listen to his advices.

PSM right now is your friend, later you can turn it off. PASM is better kept at normal as you want car to be soft rather than stiff.

regarding understeer/oversteer in a stock car - get sport alignment done, maximum possible (about of -1 deg) camber in front, -1.5 deg in rear. search forum for more details on this.

You'll get a split of opinions on your questions, I've no doubt -- but I'll wade in first. PSM? I leave mine on. Some do, some turn it off. I've done quite a bit of driving with the instructors from PSDS who always say to leave it on. They say that if you're driving correctly, PSM won't interfere. If you screw up, it'll help minimize the problem. They say it stands for "Please Save Me." I keep meaning to do some runs with it off, but I've never gotten around to it. If this is your first AX in a 911, I'd just leave it on and worry about other things.

PASM's sport setting does a couple of things. First, it firms up the suspension. Fine, if the course is smooth. Not so good if it's bumpy. So that just depends on the individual track. Sport setting also changes the throttle response, giving the engine more gas as you first step into the throttle. AX courses are relatively low speed, and I find that sport setting tends to make the throttle a little "jumpy" and harder to modulate. I tend to leave it off in AX.

"Tends" to understeer? Hey, this is a 911. You bet it understeers! That's why trail braking was invented. People try to turn their 911's into GT3's by changing all sorts of things - tire sizes, camber settings, etc. If you're driving a stock 911 just keep repeating to yourself -- "Slow in, fast out." Your car has amazing brakes. Use them. The over-and-over mistake for all new 911 drivers on a course is trying to enter turns too fast. When in doubt go in too slow. That way you can at least stay on a good line and accelerate early. As you do additional laps you can start braking a little later. This advice will be something you already know if you previously AX'ed an older 911, but if your previous car was something else you'll see a real difference in the way this one handles. Not bad, not good -- just different.

Last bit of advice is something I've seen here over and over - bring a good tire pressure gauge and use it. Keep hot pressures down to 40 psi or a speck lower, with the fronts 2-3 psi lower than the rears. (So something like 37/40 hot.) I've seen tire pressures increase by 5-6 psi afte just a couple of practice runs.

Oh - one more minor detail. HAVE FUN!

DMoore
'11 GTS
'10 Panamera 4S

Great advice. I'll start off with PSM on then.. maybe try with it off for a few laps later on. I was thinking keeping sport mode on but with normal PASM since this is how I drive every day and have grown accustomed to the feel of the throttle.

How about shifting down to first for slow turns? My old car had less torque but even then I never bothered.

most AX courses are done in 2nd gear. 997 car has awkward shifting into 1st gear, do not do it. if you have pdk car, keep pdk in auto sport plus mode.

i wouldn't shift into 1st... I am a beginner autocrosser myself... I am still trying to find best entry speeds into the cones... The slow in is a MUST! many times i find myself over-excited and i enter to fast... The result is that the car understeers like crazy... I guess being smooth is the key...

Here's a small incar from my second autocross with NY Metro PCA...

http://www.youtube.com/watch?v=0S1nFkSzayo

Sport plus on / PSM on

On the 18th we have another one... I hope to do better...

Great video! Thanks for posting.

I heard from the local SCCA that their Auto-X on the 17th has been canceled due to repaving of the lot at the Coliseum. I haven't heard anything from Metro about the 18th.

There is no information or announcement for a cancellation on the 18th. If we run on a new re-paved surface it will be great! I will definitely be there.

How do you launch off the line? This has always been an issue for me since I don't like abusing my clutch so I usually start off pretty slow.

I don't really launch the car. I blip the throttle and release the clutch fast. If it bogs of the line it bogs...

I haven't really persuaded myself to really launch the car. Coming from a drag setup EVO launching at 6000-6200rpm on the two step I really understand and know the stress on the drivetrain.

37/40 hot? On the door of my 997.1 C2 it recommends 37/44 cold. So I'd have to let out air before an autox; whereas I always heard you should over-pressure slightly. But I'm new at this too so I'm interested in hearing your reasoning.

Well, there's a couple of things. First, that 37/44 recommendation is for a full load. If you check your manual there will be another recommendation for a partial load. I doubt you're running an AX with a passenger and a full load of luggage.

Second, the factory recommendations take a lot of things into consideration. They're looking at street conditions - potholes, variable car loadings, tire mileage, etc. None of those things are a concern on the track. Your only concern on the AX course is maximum traction.

Plus, driving on the steet rarely heats up the tires as quickly as driving an AX. I've seen my tires go up 5-6 psi in the space of 3 or 4 AX runs, and I've never seen that in street driving. On a track, it's even worse. Last year on a hot day I was at a DE and forgot to check my tire pressures until after the first run session. My rear tires were up to 52 psi - and I'd started out with them at 40.

General experience (it varies from tire to tire) is that street tires start getting "greasy" on the track at hot pressures over 40 psi. So the idea is to keep the tire pressure just below that, thus 39 or 40 rear. Porsches being what they are (rear-engined) you'll always run your front tires 2-3 psi lower than the rears. Hence the recommendation.

YMMV, of course.

DMoore
'11 GTS
'10 Panamera 4S

I don't think the burnt rubber smell has worn off yet... had a blast yesterday!

Can you explain what you mean by "greasy tires"? I started off slow and did not really push the car much(was trying not to get lost). My times improved each run and my last run was the best.

Another question I had is about the rear spoiler. I tried with it up/down but did not seem to notice much difference. I think I will just keep it up in the future to help with engine cooling.

"Greasy tires" just refers to an overheated tire that starts to lose traction. If the tire overheats it loses grip - slides more easily - feels like somebody put - you guessed it - grease on the tires! An overheated tire also wears out much more quickly.

I've never worried about the spoiler and I've never had any overheating problems at all. I think it's a non-issue.

And welcome to the fold. You may just have discovered a new addiction!

DMoore
'11 GTS
'10 Panamera 4S

any street tires are greecy and have bad traction over 40psi. keep to 34/37 hot for street rubber.