Well, I can't knock mid-engines. We had an NSX as our daily driver for ten years and it never put a foot wrong. On the other hand, I'm familiar with the rear-engine configuration as well. I used to race Formula Fords. Early 911's were certainly a balancing act. Very much the same as a Formula Ford in those early days. Even with half the power we have now, the 911 had enough power to snap around at nearly any speed. That is what we might call the native trait of a rear engine car, its uneducated immature manners. But the 911's have been to finishing school since those days.

In those early days, I raced an MG and it was entertaining for the crowd -- if the driver knew how to stay out of the wall -- to snap-turn your way into the 'pit' parking slot after a run. (Actually, I suppose the crowd would have loved it either way, but it would have been an expensive way to entertain them if you blew the manuever.) With the front engine, I had to use the handbrake to initiate the snap. Years later, in a Formula Ford, I found you can do that by just stabbing the brakes and hitting power as the weight transfers. At speeds up to about 100 mph, maybe 110, you steer with the throttle.

All that is very much how they used to describe the 911. I drove them but never wanted to abuse a car loaned to me, so I have to take it on faith. In the years between, I have read they went overboard with corrective measures to be sure the car would understeer in any conventional road situation. On the track, you could push past the understeer mode and take it clear to oversteer again, but without being completely sure when the transition would occur. Moreover, I read some discussion of the car bobbling, as it moved in and out from one mode to the other, without stabilizing either way. Never drove one of those, so I can't say at all, but it sure would be a bear to lay down a laptime with that going on.

But the current model? Don't underestimate the power of continual refinement, differential tire sizes, and computer control. Ours will neither understeer or oversteer so far. At least not the way I drive. I admit that enough time in Formula Fords will teach you throttle control the hard way, so I simply may be keeping it out the weeds from hard-learned reflexes. But it doesn't feel that way. Feels my Grandma could drive this one at double those speeds on the turn warnings here in California.

I haven't been on a track yet, so I don't know what our dot two does at the absolute limit, but it feels like it would gently transition into oversteer. Likely not as extreme as a Formula Ford, and probably only if you turned off the PSM, but we really need someone with serious track experience to speak to that. I have no track time in it yet, as I say.

At any sane road speed, it certainly doesn't understeer. And I couldn't tempt it into oversteer either. When I wanted to explore the limits, one of the obvious things to do was go deep into an intersection corner, right handed, and hit the power at the point where we would hang the rear out and be wailing sideways in a Formula Ford. What modern kids call a 'drift' although that isn't what the term means if you see it in any of the older racing instruction books. (Sometime when I"m less tired, I'll describe a true drift, because it's the fastest way around a corner. That modern version is just a way to make smoke.) I didn't expect smoke in a rain storm, but I did expect to hang the car sideways for a hundred yards or so. Couldn't do it. Not with PSM engaged anyway. May try again without PSM, if this next storm develops as it looks like it wants to.

The current model, the 997.2, is one of the best handling cars I've driven for pure neutral cornering force right up to the limits I can explore on public roads. Health permitting, I'll take it to Little Willow next month when our local PCA is having an autocross run on the Streets. I'll let you know what I learn. I'll bet this one doesn't understeer the way you describe. If it liked that behavior, it sure had plenty of excuse when I tried in the rain.

 

Nice write-up! Porsche sure goes way back with their continual refinement.
The only thing is that you can't bend physics and porsche engineers are probably aware of it. Hanging a 400 lb weight outside the rear axle is going to be a problem with fore-aft weight transfer. No way to beat it. When you autocross your car, just bear in mind what I was saying about the power on/off nature of the understeer. Don't think for an instant that you will be able to just snap your car around a 40 mph turn with the throttle. (that will only **** off the turn marshalls who have to reset all the cones) You can do this technique at 100mph, but on autoX, the 911s are known for ragged understeer. (death-plow) The rear suspensions are too good at stabilizing the lazy drifts you could get out of 993s. You can do the 'scandanavian flick', which works, but who has time for that? With the newest design 911, they usually do pretty lousy in SCCA solo, with the exception of a GT3 from a few years ago. That driver won the nats by drifting his car around every corner. He has since given up on the 911 and gone to Z06s and Exiges. Now, The boxsters and caymans are different stories entirely. Just point and shoot. They can be driven smoothly or tossed around and still manage to be fast. A better driver can minimize the disadvantage of the rear engine in these situations, but the traits are there to work around. That is why stock vettes are 3-4 seconds faster around the typical 1 min. track and M3s are about even with the rear engined porsches (despite being hundreds of pounds heavier)..they have nothing to 'work around'...they simply stick, and go!! I should point out my bias-->Most of my experience is in autocrossing and I lack patience. I hate waiting for the front end to settle and then blast out the other end of the turn. I should probably study buddist meditation or something!

 

What you`ll get will really depend of what alignment you have on your car - I ran it at auto-x first on original stock (camber somewhat close to 0 front, -1 rear), than with maxed out negative camber on stock parts (-1 degree front, -1.5 rear) and now when I drive it on GT3 LCAs with -2.2 degrees front -1.9 degrees rear camber with 0 front toe - it changed car a lot. Did not have a chance yet to run it on a course - but it handles way different now from how it was at original stock settings. It is extremely sensitive now with understeer how it was gone completely.

 

+1 on that alignment! I am going to get as much as I can on the front camber. I have 2 schools coming up at Devons and don't want shredded fronts. I can't do the GT3 arms because you can't run in stock class in SCCA Solo.

 

As soon as you decide to run on r-comps you will get out of pure stock class and most serious competitors are running on r-comps anyway, plus, car really changes a lot with GT3 suspension, I would say overall benefits from this mod warrant to risk to get into more competitive class.

But it all depends of what your goals are and how serious about your scores are you. As for me I`m still learning my car and not that much concerned about my final standings, but I can say the feel of a properly tuned car is unbelievable.

It is obviously not a goal or purpose to convert any given 997 into GT3, but suspension wise GT3 mods like front/rear LCAs, upper mounts - they do change car a lot. It just makes it the way it was supposed to be and you can feel it right away. It is amazing how different steering feels with those LCAs.

Quite interesting thing - my mechanic told me that in rear axle he could get
max of -2.3 degrees of camber but when he started adjusting toe to 0.10 on both sides he had to reduce it to -1.9. Still I think -1.9 in rear should be sufficient enough for a mostly street car. Will see how this season will go.

 

In SCCA Solo, you can run r-comps, or any DOT slick and stay in stock class. Mostly Hoosiers or Khumos are used. They made street touring class for tires like the direzza and Re11 with treadwear over 140. That is the flaw in SCCA.....you can run slicks, which make most stock suspensions do things that seem odd, but you can't do any suspension mod except add a front stabilizer! In most clubs, it is the other way around (which makes more sense to me) I guess that is why I don't enjoy SCCA as much as PCA and BMWCCA series. SCCA is too serious sometimes, although everyone is friendly enough!

 

I run with NER/NCR most of the time plus with other local clubs, again, for me it is pure fun and not that much of a podium challenge, not to mention it is a pretty long way to it anyway.

With local club rules I fit into improved stock class and it is pretty much OK. One way or another it does not change much anyway. Most of cars that run at Devens every weekend got almost no stock parts left on them anyway.

 

If you want to have some great fun at Devons, there are 2 schools coming up that will have you grinning! The first is the Evolution autocross school and it runs through the Boston BMWCCA. Most of the cars there are not BMWs, BTW. Anyone can enter. Just about all of the Nat. Champs have done the school. A fellow named Keith Scala (in an RX8) took it at the same time I did and after talking to him, I found out he was a national champ from the late 70's and was just getting back into the game. At the time, I had never been on an autoX course, so you can see the variances in experience levels at the school. What is nice is that you get 30-40 runs per day and always with a passenger who is at least a 1X nat champ. Most are 4 or 5 time champs. That school is may 8 and 9. The second school is the SoloPro school and it is also incredible. You pretty much run all day with a GPS data logger on board and have full plots of every run! That school is late may. I actually have more fun at the schools than at an actual event. Everyone is friendly and you don't have to settle for 5-8 runs. Anyway, it would be great to see another porsche at these event!!

 

Great info, thanks!

 

I'm not sure I understand what that first sentence means, John, but I certainly don't have trouble agreeing with the rest of what you say. I began with autocross in that MG in Arizona in the early sixties. You could mostly race a car of that low power around an autocross track, with only a few toss-and-catch corners. Then I got addicted to full track events, hill climbs, and street races, and didn't do any autocross until we came back to the states and had a 350SS Camaro. With that much power and a front engine/rear drive configuration, an autocross was pure toss-and-catch all the way around. Felt like trying to race in a driveway. I went through most of a set of street tires in one event and didn't have all that much fun. (Though the smoke level was a spectator joy.) That's what the Corvettes had looked like when I was running an MG, but for myself I found the technique lacked either speed or finesse. I wasn't interested enough to continue with the Camaro or rich enough to buy an autocross car. A Lotus Seven would have been the car of choice in those days. By the time we had the money, I didn't have the time. (Too soon old, too late rich? Something like that.)

Now of course, I infer that they have expanded the autocross track size from comments here and there and the venues they name. The 'Streets' at Willow Springs is not a serious full track, but it sure is big enough to dwarf the off-course autocross tracks we used to arrange. I'm sure you could get a Carrera out of second gear there, though not for long. Whereas the full track has a couple of challenging corners you'd take at high rpm in third or even in fourth gear. (Not to mention one that would stretch a Carrera's legs, turn eight.)

Autocross and full track are both very entertaining ways to drive if the autocross track isn't too dinky, and the Streets wouldn't abuse a powerful car as much as a parking-lot course, so I look forward to trying it next month if I can. Meanwhile, I don't doubt your advice at all. I never learned anything but toss-and-catch to get a car like the Carrera around a tight course, so my comments were strictly about the behavior I would expect on a full track. Driving into a forty mph corner at 80 or more, and then braking heavily... yeah, I can see the car having some resistance to rotating. Understeering right off the course sounds very likely unless you do something.

What I didn't catch was what you do in that situation. Do you snap it around with the hand brake? Or what? I assume you have to take off PSM to post anything useful at those moderate speeds.

 

Basically, from what I understand, (I have never tracked the 911 chassis, only AutoX'ed), the propensity for the chassis to understeer is not as noticeable on faster and more open turns. My theory is that most of the camber curve of the 911's strut suspension is built into steering caster. What that means is, when you crank in a bit of steering, like you would in a lower speed turn, the suspension does not compress much, but the caster effects the contact patch to a large extent. (giving you the same effect of neg camber, but without the suspension moving to produce it) You don't get the same grip in those tight turns because of this arrangement and the closer the wheels get to perpendicular to the direction of travel (made worse by the variable ratio steering)will lead to the "death-plow". Compounding this is the effect of having your rear tires as a fulcrum for the engine, which sits outside the axle. When you get on the gas, the front tires lift and lose traction. All cars do this slightly, but the 911 is much more prone to adverse effects. A vid you might want to watch is a Car and Driver vid from when they comparo'd the M3 to the 911 (maybe 6 months ago). They did a 'behind the scenes' vid of the 911 on the autoX and they did some really silly combinations of throttle and steering. Anyway, it was hysterical to see the front tires just ruddering back and forth with no apparent effect on the cars trajectory. I thought it was going to do a 'wheelie'! Obviously, C&D tried to make the car look stupid, and that was not fair. They also used a base 911 with a soft suspension, but the effect was very noticeable and very, very interesting!
In regards to using some rear slip angle to get around the track, porsche has made the cars very stable in rear grip. If you have the rear end laterally loaded with grip, you can steer with throttle...but the death plow happens before the rear end becomes a factor. It is basically a split second after you get the nose to lead into the turn and most cars ask for some 'maintenance throttle' to balance the chassis. If you go for too much throttle in the 911, you can lose 20 feet in a hurry. (nose first) Be careful around curbs! I will try to post a scan of a cool friction circle diagram from motor trend that compares the Z06 around a figure-8 to the 911S. It is very interesting to see a vehicle with no understeer and poor rear grip (Z06) to a car with awesome rear grip, and plently of understeer (911).
What is really interesting is that the GT3 is much, much better at low speed neutrality than the 997.2S. At higher speeds, many here have noted that the new .2 chassis is as fast as the old .1 GT3. Obviously that is not true at AutoX speeds. I suspect it is that the GT3 suspension does not allow the porpoising effect due to the extreme stiffness they dialed in.
Oh, I almost forgot the last part: If you are heading for the Death-plow...do not add more steering angle... dab the brake and maybe hit a few cones. Best thing is to avoid the fast-in approach altogether. Trail braking can help, but you must have patience and get the nose going where you want to be and then throttle it! PSM needs to be off for AutoX!

 

Got it. My first inclination (after the first bout of understeer that is) would have been to trail in, touch the handbrake to rotate and then catch it with the power.

Damn, hope I feel up to this next month. Talking about is getting me all pumped up again.

 

Me too!, but it is snowing here in jersey
I am going to put that graph here that I promised. It is interesting and helped me understand how to attack the lower speed turns you will see on AutoX. I don't know if this will help track drivers with open courses

 

Most difficult part to drive 997 at auto-x for me is to get this feeling of how far car keeps going straight after you dial your front wheel into turn. Plus you need to have almost no free-rolling at all.
It works unbelievably good in slalom, but when, say, you need to do 90 degree turn after you redlined car at 2 gear and you are approaching at 100% throttle then go into full braking then you need to trail brake into turn with subsequent transition into acceleration - it is not like track with pure simple slow in - fast out, it is more like fast in - fast out with initial dial into turn while still braking then with full throttle you kick car into drift and essentially by the time when you start accelerating your wheels should already look right into entrance of next turn.

I do constantly overshoot this spot where you need start turning wheel without car reacting to it, all old reflexes demand to almost pass the cone by and start turning wheel only after than, but with 997 it has to be done quite well before cone and to calculate exactly the moment when understeer will be finally gone and car gets its full grip. It is quite difficult to explain with words and I may not even doing it right, but I struggled with it last season and hopefully may be will get this properly this season. People say it takes year or 2 to completely get into it. Will see.

I also find that 997` *** is way too heavy to use handbrake predictably. In case of 180 degree turn it is simple enough of course, but, say, to use it just to initiate drifting - no, does not work for me, most usually and disturbance of rear axle when you are going on limits of grip on burning hot rubber results in immediate spin.

 

Well, theory in essence how I understood it is very simple - while braking you dial in turn, when you finally decelerated enough you start releasing braking force to get good grip so you can get car to bank and while you have that banking force in effect you kick at gas to rocket car forward while it still keeps hanging its front axle to pavement by outer side of tire and so you go into turn.

Quite simple to explain logically but has some difficulties in implementation.