simsgw

Yes! I don't think I've mentioned how much I love this convertible top, but I just told PCNA so in their buyers survey so I should mention it here as well. I am amazed at how well they combined the top-down entertainment value with visibility and coupe-like acoustics when the top is up. And the look of it! Our MG used to look like we pitched a pup tent on it when we had to put up the top, and the look of convertibles hasn't changed much in all those decades since. On the highway, they look like they've grown a goiter.

But this 991 Cabriolet is just as good looking with the top up as down and it holds its shape at speed.

Great job of design and manufacturing. Now I have to coach my detailer in how not to ruin it.

Gary, who loves the tail lights too but doesn't want to sound gushy

Nicoli35

I love your car, Gary - thanks for the pics. Just wonderful.

p.s. agreed on the top. it's a very special car.

chuckbdc

TY- Looks like glove leather! Great combo.

simsgw

Well, if that is the acid test, then we need another term. When we take a sports car to the track where the oil and grease and exhaust deposits of a long dry season are being washed to the surface, that would be ... what? Maybe "the ultimate test"? Of the 'sport' aspect? Something worth knowing about anyway, so herewith a report. I am a believer in break-in, as already discussed, but I had committed to instructing at the Fairplex event hosted by Grand Prix Region of PCA. Simple courtesy required that I register my new car, right?

Okay, I couldn't wait for 2,000 miles. I just promised myself moderation. Nothing but sport mode to inhibit the enthusiastic high-rpm downshifts of "sports plus", early up-shifts commanded by myself, and no manual downshifts so I wouldn't be tempted to grab for more torque, aka rpm, coming out of corners. And that meant inhibiting the computer-directed downshifts in the same situation, so I was careful to use only part throttle. Really I was. My experienced passenger kept one eye on the tach when I was busy, so he could alert me to 'over-revs' as defined by the "keep it under 4000" rule.

The 120-mile Saturday drive in the rainstorm held no surprises except the rain-sensitive wipers. I realized after half an hour that I never had turned on anything, but the system was automatically clearing the window at appropriate intervals. I noticed only because I thought I wanted a little more spirited motion when the wipers activated and I had to remember what the manual said about increasing the speed of wiper action. Car felt very planted at all times, despite occasional freeway sections that had visible standing water. This wasn't a patch on the deluges I've seen in Florida, but it is what Southern California calls a rainstorm and we begin to speak of the El Nino effect returning.

Sunday was forecast as clearing and my 'student' for the day confidently forecast one final rain shower that would last less than half an hour. (I wondered what astronomer had to do with meteorologist, but fortunately I considered briefly before making a fool of myself. Let's just say he has routine professional need for sources.) Clearing or not, after 34 hours of light to moderate rain, the flat track at Fairplex was so wet they sent out one of those giant vacuum cleaners. I meant to look but was distracted mounting my rented transponder. I always picture something like the Zamboni's they use in hockey rinks.

They only paid for one pass because they had a better solution: send out us instructors for twenty minutes, with encouragement to "develop a dry line" for the novices to come later. Aiming deliberately for the deeper standing water -- aka ponds, lakes, and estuaries -- was a social goodness to be embraced. In my new Cabriolet. Sigh.

My student asked for ride-along privileges and giggled like a fool every time I had the Cab sideways. (Okay, okay. The objective version might be that he only chuckled, but to each his own opinion.) Honestly, it didn't happen much. In fact, almost not at all, which was startling when you consider I was taking a car never driven "in anger", as we say, around a track I'd never driven when wet, and at speeds no sane civilian would attempt on a dry surface. And I was very socially responsible. Those Pirellis must have pumped a fishpond of water for every minute I spent out there.

Afterward, I checked the g-meter out of simple childlike curiosity (objective version: to show off a new gadget). The 991 Cab and the factory Pirellis managed 1.15 g's in right turns, 1.13 in left turns, and 1.14 g's in braking. Very impressive for wet track performance, to say the least. I'm sure they reached that level only on the corners without standing water, but a wet surface still drops the compound's working temperature and having run through standing water only seconds before each corner drops it drastically. I began to respect the Pirellis that I'd been considering only as temporary expedients until I could wear them out and put on the Michelins I usually choose. Possibly Pirelli has made design changes since I last used them. ["Around 1969," he muttered.]

My 'student', whose title I put in quotes because he won the driver-of-the-year award in his own region last year, was quite snotty about beating me in those morning sessions. "130 milliseconds" he crowed. In fact, it was only 123 milliseconds, damn it. Scientists always leave the precise arithmetic to us engineers. But still, I admit to some mild intellectual interest in whether I could thump his sorry *** if I just extended the break-in limit by a thousand rpm. And grew a pair, to use another racer's expression. So I did. Both.

During the formal Time Trial laps, which comprise only an out-lap, two timed laps, and an in-lap, I extended the shift point to 5,000 rpm instead of four, and... well, I might have spotted one run to 6,000 when my attention was on balancing the car on throttle through the sweeper. Using part-throttle, we saw 114 mph on the longest straight just before the braking point. I have decided to think of this day as one of those 'excursions' recommended for classical break-in technique. And break-in is nearly done anyway! The odometer passed 500 miles during the first morning session.

I hammered my student with a time faster than his by a brutal ten milliseconds. I hope he recovers from the emotional scars.

All joking aside, and joking about him as a student is the only way to describe that day, the 991 was stunning. I still can't vouch for its power but I was keeping up with a 997 GTS, and a Cayman driven by a driver-of-the-year, while using part throttle for Heaven's sake. Some of that is down to my knowing race techniques he did not, which is why he asked for some dual time; but most of it is down to the very high limits of this chassis. Damn, it is good. On those timed laps, I measured 1.25g in braking, 1.21g in right turns, and 1.18g in left turns. Yes, a dry line was developed, and this does suggest I am favoring my back in corners where I can't use my arm on the door to brace myself, but I can live with a 0.03g bias in my driving. For those who don't know, 1.25 g is what we figured race rubber on a Formula car could produce without aero aids in my admittedly generation-distant racing days. It is seriously good grip.

I would object that the g-meter is subject to the classic problem of chassis tilt affecting the readings, except that first, I know several ways one can compensate for that with modern computer-controlled suspensions; second, this chassis doesn't tilt very damn much in the first place; and finally, those readings were consistent with the observed performance compared to cars whose cornering I've measured in more traditional ways, like the 997 GTS I kept overtaking in turns.

The Pirelli compound is very impressive and the 991 chassis is taking every advantage of those tires. Even more important to us as sports car owners, the 991 felt agile and quick from the first lap to the last. I laughed out loud at being able to dodge puddles at racing speed while cornering. Remember, this is coming from a guy who began with sports cars in the sixties and has cars like MG and Lotus Elan and Formula Ford in his memory banks for comparison purposes. The traits of a touring car are matters of personal preference, but... and saying so will annoy hell of out of enthusiasts who haven't committed to the 991 yet... this is a better sports car than the 997, which I tracked extensively. Porsche have done it again.

Unless something dramatic happens around here, you have my final impression of this car:

Wow.

Gary

ADias

Excellent write-up. Great that you are having fun.

Now we need a tire temp analysis.

simsgw

I thought about that. But only briefly. Bending over wheels shrouded in fenders spattered with abraded Pirelli compound and mud with a pyrometer seemed like too much to ask of a 'student', even one enjoying a good giggle on track. Besides, I doubt measurements in the pit would have meant anything. The rough indication of temperature based on pressure rise, observed in the pits, suggested the tire carcasses were not more than 130 fahrenheit. That's at least 30F under the working range I'd expect, so the Pirellis either have a remarkably low temp range for high-performance tires or they were cooling so quickly once I left the track that the pit pressures meant nothing about their on-track temps. And I definitely had no time to check pressures on track this time. I was too busy giggling... uh, I mean chuckling. In a completely mature way.

It really was a very entertaining day. My 'student' just sent me a note saying the same thing and complaining of sore muscles from withstanding the g-loads in my laps. I pointed out that ten milliseconds slower does not appreciably reduce the g-loads that I had to tolerate from his own driving. And yes, I am so sore that in the hotel I woke in the middle of the night to pee and almost cried out when I stood and tried to walk.

Gary

ADias

I imagine the tires were cooling fast. Were you running the std 31/34 (low load <160MPH) for the 991?

The 130F hot temp estimate based on measured tire pressures indicates that your PSI increases were 5PSI ballpark (0.8PSI/10F, assuming typical mid day 70F Fontana ambient temp at this time) seem low for track. I routinely see larger pressure rises on typical canyon drives, with Michelin, Bridgestone or Pirellis.

Re soreness... yeah it hurts.

draxa

Somewhat off-topic but...... the new 991 key-fob does not appear to allow a 'manual unlock' of the door if the battery fails or the car is left idle for a period. Is that correct? If so, what does one do?

deturney

Use the "Emergency Key"-in US Manuals it is under "Opening and Locking" starting on page 14. Flip the key over, slide the release button to the side and pull out the Emergency Key".

Now returning this thread to Gary and his thoughts on his new 991.

draxa

Thank you; in defence of my ignorance, I don't actually have my car (or a manual) yet! Probably sometime in December.

chuckbdc

Garry,
Thanks for the detailed report. I knew the "wow" part, but enjoyed your Speed Channel rivaling discussions of Pirelli. I have put on over 8k miles since March and too was looking foward to swithcing to Michelin Super Sports. I enjoyed them on my previous car (Boxter S RS-60), but the Pirellis are wearing and performing far better than expected. At this rate (and no more track temptations here in the east for the season), I await more reports.

simsgw

I was indeed using 31/34. No evidence to support a different choice of course. And the pit pressures were 36/39 as you surmise, Tony. It does seem very cool for a car that just finished pulling g-loads that high, but of course a tight canyon road can have a Porsche pulling about one g very easily. Those canyons, they do the darnest things to our cars. Shame on them.

Seriously, the heating effect of 1.2g is much greater than 1.0g, let alone the likely average of about 0.7g sustained on a canyon drive. The cooling effect of a track still evaporating water can't be over-stated. I'm sure the temps were more like 140-150 on the sweeper for a hot lap (using one example), but a single cool-down lap could drop the tire temps like a rock.

It was a perfect day to teach two-stage braking for exactly that reason.

Gary

ADias

Thanks for the confirmation. The 'hot' pressures still sound low to me for the driving you were doing. One of these days, after a spirited drive I will save my SC data log to a thumb drive and check G-maps on a spreadsheet. That actually gives a very good view of sustained G-loads, as spurious noise peaks can be discarded.

simsgw

Can we do that? Damn, that's going to be interesting. I really need to finish reading the PCM manual.

Remember that pressures are high or low only according to the effect on the contact patch and tire temperatures. The smaller contact patch with the rising temperatures tends to make the tire work less hard, which caps the temp rise. And the tires certainly were not *too* hot, so the pressures didn't need to be higher. Although I would like to see working temps around 160 because most tire compounds aren't in their effective working range much below that. That's why I am convinced the tires were cooling rapidly because the on-track temps couldn't have been that low and still perform as observed.

I don't know for sure, because I haven't been able to find data from Pirelli on their compound. Maybe I'll be able to pry more information about modern tire compounds out of Michelin at Tech Tactics the first of next month.

Gary

ADias

Of course! Check your PCM manual - look under Sport Display and Transferring Data. On the PCM display you do that under Trip>Option>Sport Display>Recordings.

Once you have the data file let me know and (offline) I will point you to the tools to analyze it.

Note: the above is in the 997.2, but I presume the same is in the 991, given that it shows peak values. Peak values, as you know, are less reliable and probably optimistic, and the raw data is what's interesting. You get a lot more than Gs in the data dump.