Impressions of GT3 (Manifold)
10-29-2015, 12:30 PM
#256
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So my one suggestion at this point would be to work with a race shop which has put in the time to come up with a setup which has been proven to work well for the 991 GT3 - DIY or being a guinea pig for a shop which is learning may not be the way to go. The setup may vary somewhat between drivers, but apparently numerous customers have liked TPC's setup. I plan to get the setup done next week, and will hopefully be able to track the car in mid November to try it out, and will then report my observations.
10-29-2015, 01:18 PM
#257
I can't share any proprietary info, but from talking with TPC Racing, I have the impression that having a good geometric setup for the car is key, and then both the SC2 and TR will work well, and the optimum hot pressure will be more a function of the tire rather than the setup.
So my one suggestion at this point would be to work with a race shop which has put in the time to come up with a setup which has been proven to work well for the 991 GT3 - DIY or being a guinea pig for a shop which is learning may not be the way to go. The setup may vary somewhat between drivers, but apparently numerous customers have liked TPC's setup. I plan to get the setup done next week, and will hopefully be able to track the car in mid November to try it out, and will then report my observations.
So my one suggestion at this point would be to work with a race shop which has put in the time to come up with a setup which has been proven to work well for the 991 GT3 - DIY or being a guinea pig for a shop which is learning may not be the way to go. The setup may vary somewhat between drivers, but apparently numerous customers have liked TPC's setup. I plan to get the setup done next week, and will hopefully be able to track the car in mid November to try it out, and will then report my observations.
Last edited by Mech33; 10-29-2015 at 03:51 PM.
10-29-2015, 02:03 PM
#258
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Even better would be for Porsche to give us the recommended parameters for three scenarios, with accompanying instructions on the setup process as needed: (a) primarily road use, (b) mix of road and some track use, and (c) primarily track use.
As it stands, IMO the car does come set up well from the factory for track, but it appears that it can be made a little better.
10-29-2015, 06:34 PM
#259
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I can't share any proprietary info, but from talking with TPC Racing, I have the impression that having a good geometric setup for the car is key, and then both the SC2 and TR will work well, and the optimum hot pressure will be more a function of the tire rather than the setup.
So my one suggestion at this point would be to work with a race shop which has put in the time to come up with a setup which has been proven to work well for the 991 GT3 - DIY or being a guinea pig for a shop which is learning may not be the way to go. The setup may vary somewhat between drivers, but apparently numerous customers have liked TPC's setup. I plan to get the setup done next week, and will hopefully be able to track the car in mid November to try it out, and will then report my observations.
So my one suggestion at this point would be to work with a race shop which has put in the time to come up with a setup which has been proven to work well for the 991 GT3 - DIY or being a guinea pig for a shop which is learning may not be the way to go. The setup may vary somewhat between drivers, but apparently numerous customers have liked TPC's setup. I plan to get the setup done next week, and will hopefully be able to track the car in mid November to try it out, and will then report my observations.
Please keep us informed of initial impressions, on road then later on track etc.
10-29-2015, 06:49 PM
#260
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I think the challenge is that all the geometry parameters need to work together well as a system - cambers, toes, caster, ride heights, rake, roll centers, sway bars, etc. Without deploying some real engineering expertise backed by acquisition of suitable test data (beyond lap times, G-forces, tire wear, etc.), we're just guessing on what to change. And as discussed in Joe's thread, it seems that this car is especially sensitive to the suspension geometry, maybe in part because of the interactions with RWS, PTV+, and PASM. I'm certainly no race car engineer, I just wanna drive!
10-29-2015, 11:56 PM
#261
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Agree with you here. I dont have front lift and purely from a practical point of view I have little interest in dropping the front to increase rake and accommodate more aggressive settings as may be the case based on what you are alluding too (which I believe may well be correct - that its is a system of around 4-6 key variables all of which need to be taken into consideration for best overall outcome). I suspect the race shops in Germany particularly will have a good understanding of how the chassis should be set up as there are many 991 GT3 otherwise "stock" running in the VLM series over there these last two seasons including tracks such as Spa & HH short etc. We could certainly benefit form anyone who has had a track set up over there my Manthey etc to chime in. Im sure some US shops are also learning plenty but it would seem a shop supporting race series including the 991 GT3 is always a good place to start...
10-30-2015, 12:04 AM
#262
Three Wheelin'
Originally Posted by rm21
I also just did a Ross Bentley webinar on suspension tuning and learned a nice trick. If you put an air-dryer (basically a desiccant cylinder) inline from your air compressor, you can get the humidity out of your air and it is far easier to regulate pressures. He suggested it is a bit better than using nitrogen. It is a pain, since you need to deflate and inflate your tires 2-3 times, but since I generally don't trailer my car and have access to a big tank of nitrogen, it is a nice poor man's solution.
.
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Rich do you have a link to which dryer you went with? They seems to be all over the place in price. I run into this problem bad with my compressor even with draining it.
10-30-2015, 09:20 AM
#263
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Agree with you here. I dont have front lift and purely from a practical point of view I have little interest in dropping the front to increase rake and accommodate more aggressive settings as may be the case based on what you are alluding too (which I believe may well be correct - that its is a system of around 4-6 key variables all of which need to be taken into consideration for best overall outcome). I suspect the race shops in Germany particularly will have a good understanding of how the chassis should be set up as there are many 991 GT3 otherwise "stock" running in the VLM series over there these last two seasons including tracks such as Spa & HH short etc. We could certainly benefit form anyone who has had a track set up over there my Manthey etc to chime in. Im sure some US shops are also learning plenty but it would seem a shop supporting race series including the 991 GT3 is always a good place to start...
10-30-2015, 09:38 AM
#264
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Cool! I was starting to think I was crazy! 
My current stance on the TrofeoR after going back to cup2 is that my 'butt' tells me the TrofeoR grip a touch more than the cup2, but just not enough for it to really be picked up on the accelerometer. However, the cup2 are easier to manage at the limit, which makes me faster with the cup2. The biggest negative of the Trofeo is what you talk about above. Having to fiddle around with pressures all of the time is a total PITA. Not worth it to me. Give me the cup2 that I can set and forget.
If you ever run at the tracks in norcal, I'd be happy to compare data!
My current stance on the TrofeoR after going back to cup2 is that my 'butt' tells me the TrofeoR grip a touch more than the cup2, but just not enough for it to really be picked up on the accelerometer. However, the cup2 are easier to manage at the limit, which makes me faster with the cup2. The biggest negative of the Trofeo is what you talk about above. Having to fiddle around with pressures all of the time is a total PITA. Not worth it to me. Give me the cup2 that I can set and forget.
If you ever run at the tracks in norcal, I'd be happy to compare data!
http://www.mcmaster.com/#5163k17/=zlaofw
10-31-2015, 08:37 AM
#266
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At this event, there was a driver of 997.2 GT3 on Hoosiers and stock engine/transmission who said he was hitting 174 at the end of the back straight based on his speedometer. I think his speedometer must have been way off. Even with a better exit speed from Oak Tree and braking later, no way he can be 20 mph faster than our car. Even this monster is 'only' hitting 171:
10-31-2015, 10:16 AM
#267
Nordschleife Master
Originally Posted by Manifold
Just noticed that your speedometer seems to match GPS-based speed to within 1 mph up to 155.
At this event, there was a driver of 997.2 GT3 on Hoosiers and stock engine/transmission who said he was hitting 174 at the end of the back straight based on his speedometer. I think his speedometer must have been way off. Even with a better exit speed from Oak Tree and braking later, no way he can be 20 mph faster than our car. Even this monster is 'only' hitting 171:
At this event, there was a driver of 997.2 GT3 on Hoosiers and stock engine/transmission who said he was hitting 174 at the end of the back straight based on his speedometer. I think his speedometer must have been way off. Even with a better exit speed from Oak Tree and braking later, no way he can be 20 mph faster than our car. Even this monster is 'only' hitting 171:
11-06-2015, 07:52 AM
#268
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Agreed. Common issue down under too. I've never done a track day without telemetry. My GT3 reads around 3-4kmhr higher on speedo vs GPS at 145mph/235kmph. Only cars I've come across that will beat it's vmax on our front straight are GTR Nissan and 991TTS by 3-9kmh. Definitely never seen a 20kmphrdifference in that straight even with 680kmphr GTR
11-17-2017, 06:06 PM
#269
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Is anyone else bothered by the distinctly slow auto shift at 9000? Mine is very noticeable on the 3 to 4 up shift. I have gotten in the habit of using the flipper to put it out of its misery. Is there anything that can be done? E.g., it would be nice to be able to change the shift point to 8800. It would be much faster.
Dave
Dave
11-17-2017, 06:21 PM
#270
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OMG, how did this old thread get revived?