Manifold

I'm sure it's been covered in the million other GT4 threads, but what's the consensus on the lap time delta between the GT4 and 991 GT3, assuming good drivers?

I ran across this video of a GT4 at my home track, and the cornering speeds seem close to my 991 GT3, so I'm thinking that the lap time advantage of the GT3 may come down mainly to the extra power on the straights.

Beantown Kman

Assuming you have equal drivers who are competent at driving both platforms at a high level, it will depend on the track. At the "horsepower" tracks that have long straight sections, the GT3 will have a big advantage. At shorter, tighter and more technical tracks, that HP advantage is reduced and the GT4 will have a better chance of keeping pace.

Manifold, you and I met at VIR a few weeks ago. You may have seen some of the recent posts on this forum from people who were at VIR recently for their first event there with their GT4's. They've reported lap times there in the 2:04's and 2:05's on mostly stock setups. As a 991GT3 owner how do you think those times stack up against those of a good driver in your car in oem form?

orthojoe

Interesting question that I'm hoping to find out myself.

A point of discussion for pure bench racing:

- randy pobst ran 1:37 at Laguna with the GT4
- randy pobst ran 1:35 at Laguna with a turbo S shod with equivalent dunlop sport Maxx race tires
- if we assume that the turbo S on equivalent tires is faster than a gt3 and that the gt3 is faster than the gt4, then the GT3 falls in a 1:36, which is 1 second faster.

Only 1 second? If true, very impressive.

BGB Motorsports

Laguna is a track that rewards mechanical grip more than power. Any track with a long straight will go to the advantage of the GT3 with PDK. 390 to 475 is a big power gap to overcome.

Archimedes

Yeah, Laguna's not a horsepower track, so the continuum of lap times of anything but a few super cars gets really compressed there.

Manifold

Yes, of course, it was great meeting you at VIR!

I'd like to see videos of those 2:04/2:05 GT4 times at VIR, given that this video shows a good pro doing 2:08.31 in a GT4 with what's supposed to be improved damping control:


I didn't get lap times when I was there at VIR in the GT3, but would estimate 2:05ish. Rear tires were likely approaching heat-cycling out, and I'll advise if I can think of other excuses. But there was definitely more in the car. As one of my instructors once answered when I asked where specifically on the track I can go faster: "everywhere".

Beantown Kman

Take a look at GTS Nut's thread comparing his New GT4 to his old 981 with a 3.8 installed by BGB. He was doing 2:05's in the GT4. https://rennlist.com/forums/gt4/9043...-8-cayman.html

orthojoe

You guys are right, the lap time differentials between my old spyder and the gt3 were the smallest at Laguna. Now I know why. Manifold, what were your differentials between the Cayman R and the GT3? The GT4 must be somewhere between.

My differentials between the GT3 on cup2 vs spyder on nt01:

Thunderhill over the top cyclone config
1:58 vs 2:04 - 6 seconds

Sonoma raceway
1:47 vs 1:52 - 5 seconds

Laguna
1:38 vs 1:41 - 3 seconds

Manifold

I'd like the see the video/data, but my sense is that the GT3 really doesn't have much (or anything) over the GT4 in the corners. The power advantage of the GT3 is significant, but the torque advantage isn't as significant, and the GT4 weighs less. So even on a "power" track, the delta between the two cars may not be as big as some people might expect.

We pick up my wife's GT4 tomorrow, but unfortunately it probably won't see the track until March.

Manifold

That all sounds about right to me. With the Cayman R on NT01 and GT3 with Cup 2, both cars pretty much stock, my best times at Summit Point are about 1:24 and 1:20, so 4 s delta. I clock that GT4 in the video at about 1:22, and he seems to be driving it pretty well (and had Cup 2, but I don't know about mods). I see Summit Point as more of a grip track than power track.

RDCR

Joe,

I can't remember, had you done any engine mods to the Spyder?

orthojoe

Stock power. Only mods were tires, brake pads, and lower control arms to run aggressive camber.

RDCR

Nice! You were really dialed in with the Spyder at LS!

GT3 Nut

Sorry I don't have any video proof. I haven't set up a video in my car since back 2009-10 when I raced a 997 Cup. I don't have a fancy set up like the guys who post those with data overlay. Honestly I just use a basic aim lap timer to see how I am doing but I don't get into analyzing data anymore. If I was going to be racing again or felt the need to improve so I could be more "competitive" at a DE then maybe I would look into that more. But I don't expect to be racing in the near future and I am just doing 3-4 events a year and I go just to have fun. I am not the fastest guy nor the slowest. However, whether you believe it or not -(since the posted video above is only a 2:08) - I can tell you that I did run 2:04's in my BGB car and in my GT4 on cup2s a bunch of 2:06's and a couple of high 2:05's. I am confident that if I had open track with a good "rabbit" to chase I can do 2:04's in the GT4 with the crappy cup2s - especially once I put harnesses in the car. I dont know what that will translate into on a set of Hoosiers - but probably 2-3 seconds at VIR??
Hopefully we can run an event together and you can see if my quoted lap times are accurate. If I ever decide to get a video set up and can post a video in the future I will. There was a guy in a nicely set up grey 996 GT3 on Hoosiers that we were running together on Saturday and he knows we were running the times quoted. I think he had a 2:05.2 as his best and I think mine was 2:05.7 if I remember right. He was following me most of the session and afterwards he actually asked if I had gotten into the 2:04's as he suspected I did because he was a low 2:05. But I didn't get any better than a high 2:05. It was possible that with a clear track it would have been such. But we were having a great time without being over the edge. Most of the slower traffic was aware and courteous.

In comparison I was running 2:07's in a 2011 Boxster Spyder on Hankook z251 tires. That car had a GT3 front sway bar and a tarret rear bar. It was one of the best cars I drove in my opinion. And in the past - maybe 2008-09 I was running 2:05's in a stock 997.1 GT3 RS on old hoosier R6's. The track was also slower then - before the new pavement and improved curbs. And I was probably more on my game as a driver also. I ran a 1:56 during the 2009 PCA Club race in a 06 997 Cup. I dont know that I could do that now. When you dont drive as much your skills get rusty.

I think that the lap difference at a track like VIR between a 991 GT3 and a GT4 is probably 3-4 seconds with equal tires and drivers. But thats just my speculation. I dont have a new GT3 to compare for sure. I speculate that equal drivers in a 997.1 GT3 and a new GT4 would be very close in lap times. I think a 997.2 GT3 would be 1-2 seconds faster.

Bottom line is that the GT4 and GT3's are very fast cars that can make us look like good drivers.
You obviously can get around a track pretty quickly yourself based on your times you mentioned at Summit in the Cayman R and your GT3. If you were running 205ish at VIR, that is also pretty darn fast. So when you have an opportunity to compare your GT3 and your wife's GT4, I would be really interested to hear you thoughts based on actual experience and seat time rather than my speculation.
Please report back when you can.

Manifold

^ GT3 Nut, thanks for the detailed info. Wasn't looking for 'proof', but rather interested in speeds at various points on the track.

Our Cup 2 tire is ok, but I've found that it's only in the sweet spot for a few laps if the tire pressure is right. Something like an R6/7 has substantially more grip and should be several seconds faster at VIR. I'm tempted to try a tire like that on the GT3, but that raises issues of warranty and having to trailer the car, as it does with the GT4.

Though a fabulous track, VIR will likely always scare me more than other tracks, mainly because all the complex 3D geometry happens at rather high speeds. Odd as it may sound, I'm more comfortable at tracks like Palmer and Shenandoah - which also have complex 3D geometry as well as walls not far off the track - because the average speeds are lower. But 2:05ish in the GT3 at VIR on the Cup 2 tires isn't overly difficult or scary, and I'd love to see what a pro can do. Oh, and your 1:56 in the 997 cup is moving!

I expect to do a fair number of days next season in both the GT3 and GT4, from VIR north along the east coast, so let's definitely look for each other!