Archimedes

O really... The lap time I quoted was set by Christian Gebhart on April 15th in dry conditions. It's posted on the Nordscleife lap time list with an ID number. Here's the video.

As regards a comparison, the C2S has more power, better grip and, at least with PDCC and SPASM on board, has a fantastic suspension. Two very different instruments/approaches that achieve similar results. And again, the C2S was on stock tires, not the SC2s the GT4 had. The GT4 is not a GT3, it's a faster Cayman. And I have no doubt someone will turn a faster lap time than 7:42 in a GT4, but not likely by much, so they'll still be pretty comparable. Porsche is claiming a 7:40.

BTW, the sound the GT4 is making in the video is orgasmic.

RocketGuy3

Logically speaking, it's just hard to imagine a reason for the GT4 being any slower than a 911S. Better brakes, better balance, better suspension, better tires, lighter. Just a very small power deficiency (from what I've heard, even smaller than Porsche's "official" numbers indicate, but I don't know).

I guess the proof is in the pudding... but there's just so many variables with all these lap times.

Archimedes

Weight difference is 120lbs, and a C2S fitted with PCCB, PDCC and SPASM isn't gonna have much of a disadvantage to the GT4 in either the braking or suspension department. And the C2S has more power (total and per lb), better rear grip and a better drag coefficient. On most tracks I do think the GT4 will be faster, but the margin won't be very big. The 991 C2S, properly equipped, is still a very capable car on the track. Throw on SC2s and it's even more so.

gtr

Maybe on larger tracks they are comparable but on smaller tracks i'm guessing the GT4 will win agianst the 991s. In that motor trend test the GT4 is already faster than the Ferrari 458, Corvette ZR1, and the R8 V10 plus on the streets of willow. I doubt the 991s is faster especially if it's manual vs manual.

RocketGuy3

120 lbs is not insignificant, but you're probably right that the brakes will ultimately be a wash since neither is likely to fade after a lap or two around the 'Ring. I find it difficult to imagine that the rear grip will matter very much on most tracks with how much power each of these cars has. I don't think the GT4 is going to start trying to oversteer much more with, what is it, 4% more weight up front? Especially given the meaty tires it has back there, along with the rear wing's downforce.

In any case, even if the speed comparison is nearly a wash, that's a win for the GT4 in my book, but it still seems likely that the GT4 is faster overall.

... But yeah I guess, the lower drag coefficient and higher power output probably make the difference on a track like the Ring with so many long straights.

Archimedes

But they said the same thing about the 981S vs. the base Carrera, but even on a short tight track the lowly base Carrera with zero performance options stomped it.

Again, I think there are tracks where one would be faster and some where the other would be faster, but I'd bet the difference is not very large in either direction anywhere, especially if you put them on the same tires. The idea that the GT4 is a super light race car and the 991S is comparatively an overweight touring car is folly. It's good marketing speak, but it's simply not reality.

Archimedes

The standard 991S wheel/tire sizes are identical to the GT4s and the optional wheels are even wider out back with 305 rubber. Plus the engine position simply gives it more rear grip coming off the corners. I have 295s on my CS and 305s on my C2S. The Carrera has a more rear grip and is simply easier to get the power down on exit. And a SPASM car has more downforce than a stock Carrera, as the wing deploys higher and steeper than a standard Carrera, plus its got a 20mm drop. There's little to nothing separating the GT4 and a well optioned C2S from a performance perspective. From a money perspective, about $25k, at list sticker vs. sticker.

gtr

We will wait and see but please help me understand your logic.

GT4-has GT3 front suspension, GT3 brakes, lighter weight, mid engine layout

is equal to

991s-has smaller brakes, engine in the boot, heavier weight, non motorsport tuned suspension.

2slow2speed

BTW: IIRC the ring laptime for the 991C2S with PCCB/PDCC/SPASM was set with a car that was equipped with street tires and PDK.

Equip that same 991C2S with MPSC2's and it might have been 5-8 seconds faster at the ring.

Update:

Completely forgot about the active diff (e-diff) on the 991C2S, PTV+ that also has some serious advantages over a regular mechanical diff + brakes (PTV) when putting the power down.

Archimedes

A 991S properly equipped for a performance build would have PCCB brakes, a slightly better HP/weight ratio than the GT4, a sport suspension with Sport PASM and PDCC, and PDK. And yes, I believe that package wouldn't be far off the GT4 lap time on a big track.

And again, the GT4 is slightly lighter, but it also has less power and actually a slightly lower HP to weight ratio than the 991S.

Bardman

PDK in the 991 would be a counter point to some of these.

From the MotorTrend Thread:

gtr

He was talking about tire advantage thus I had figured you guys were comparing platforms.

Manual vs Manual
Similar power to weight ratio
Porsche's superior 911 chassis vs budgeted mid engine platform
Which layout is faster? Don't know by how much but I'm betting on the GT4 to be faster 4 out of 5 times based the platform. But some people feel it's about a wash with the 911s.

I'm sure most fans will put this to the test and maybe Caymans will finally get some respect from 911 owners.

RocketGuy3

Oh, I somehow missed that you're comparing it to a performance-optioned 911S. Yeah, once you add PDK and whatnot, the S will almost certainly be able to hang with the GT4. But of course, as you mentioned, by that point, you have widened the price gap pretty significantly.

Petevb

On equal tires I agree a properly equipped 991S is faster on average. PDK and active roll control are obvious advantages, but I suspect it's really the rear suspension that carries the day, mainly over bumps or under power on the limit. On a smooth track the GT4 will do very well, but it'll be hampered by tall gearing if things get too tight.

Some early tests of the 991S by Sport Auto, etc showed very quick times, but in hindsight the car looks like a ringer. Still, over a single lap GT4 vs performance spec 991S will likely come down to the track. Where the GT4 has a big edge is endurance, durability and tune-ability. Endurance spec brakes and larger wheel bearings are designed for sustained track abuse, while dialing in proper camber and handling balance will make both the tires and driver much happier.

The big issue isn't speed, however, it's feel. A base lotus Elise won't lap quicker than many performance sedans, but the feel behind the wheel will be entirely different. Similar here. Speed isn't the goal, it's a means to an end.

acey81

You have to look at the stock GT4 as a baseline, and with a proper track setup (something that the 991S won't be able to do) the difference between the cars will be bigger, especially over more than one lap.

But the electronic trickery of the 991 will run it close over a single lap.