On track experiences and video's 991 GT3 only.
10-26-2016, 10:27 PM
#916
Rennlist Member
Thanks Rich. I find this all very interesting. As you know Im not a believer that there is any performance benefit in camber on increased these cars - all it helps with is managing tyre wear as yoi day, and I find on the GT3 at least the tyres are usually cycled before worn out using -2.00-2.200 F+R so I see no need to go further - at least with MPSC2.
What is really interesting if the height and rake. I assume this matters more to your chassis as you have probably double the rear downforce at speed with the Crawford wing compared to standard (I believe the RS has 3x the GT3 downforce at the rear at 300kmph so Im guessing you are closer to the RS than the GT3), I guess front downforce becomes even more important here to offset the rear and ensure you dont have huge understeer. It almost certainly also improved the frontal CD resistance.
How much lower have you taken the car front and rear?
Are you aware there are some Cup front wheel undertrays that do not have the hump that gets constantly damaged. They are $40 a pair and bolt pretty much straight up. No more damaging that part and they can be bought just the front part you need :-). If you want the part number ill post it. I bought these and had them fitted and they are great - havent tried them on the track to see if they cause any issues etc...
What is really interesting if the height and rake. I assume this matters more to your chassis as you have probably double the rear downforce at speed with the Crawford wing compared to standard (I believe the RS has 3x the GT3 downforce at the rear at 300kmph so Im guessing you are closer to the RS than the GT3), I guess front downforce becomes even more important here to offset the rear and ensure you dont have huge understeer. It almost certainly also improved the frontal CD resistance.
How much lower have you taken the car front and rear?
Are you aware there are some Cup front wheel undertrays that do not have the hump that gets constantly damaged. They are $40 a pair and bolt pretty much straight up. No more damaging that part and they can be bought just the front part you need :-). If you want the part number ill post it. I bought these and had them fitted and they are great - havent tried them on the track to see if they cause any issues etc...
I'm not sure exactly how much the car has been lowered. My race shop is unwilling to share the full setup specs. But I think Porsche publishes guidelines on this, and with a little trial and error, it shouldn't take much to get it dialed in. It is hard to argue with the benefits of a lower center of gravity, which is why I'm surprised it hasn't come up more often as a major variable in all the suspension setup discussions.
I wasn't aware of the Cup car part. Would love to have the part number. My only concern would be with changing the airflow there, which might affect brake cooling. I'll check with my dealer to see if they have any issues with the mod. Thanks for the tip.
10-26-2016, 10:36 PM
#917
Rennlist Member
Rich. Do you have your smartycam calibrated correctly for G? Id be interested to see your AIM trace for G with the new tyre combo (perhaps correlated against prior running at the same track on other tire/wheel) combo if you have it? This is a good way of telling teh extra grip you are getting - I even see a difference between new tyres vs say tyres with 20+ heat cycles on them...
10-27-2016, 08:42 PM
#918
Rennlist Member
here is teh cup part. Id does not affect airflow to the brakes (air is channeled through the front valance for this). They actually probably channel more air up there as they are profiled to lift air into the arch, a reason I suspect they are on the 991 Cup cars. If anything it will increase amount of air that is being disturbed by the front wheels when they are "dead ahead", however I suspect this is so minimal you wont notice it with all your other aero changes. Under brakes the nose dips so this is not an issue at that time....
Ive had these fitted to the car and they make daily driving much easier over bit speed humps etc. they are a PAG Cup part so no warranty issues, they are quick to fit and they are 5x cheaper than the originals and never will need replacing.
Ive had these fitted to the car and they make daily driving much easier over bit speed humps etc. they are a PAG Cup part so no warranty issues, they are quick to fit and they are 5x cheaper than the originals and never will need replacing.
10-27-2016, 10:08 PM
#920
Rennlist Member
Yes Peter. Fits RS. My original ones were so greyed and bashed up I doubt they were smoothing any airflow at all. Now I can drive over speed bumps without hearing them grind...
10-31-2016, 10:54 AM
#921
Rennlist Member
Thread Starter
2 laps Sebring playing with setup and Vbox. Both work in progress.
This day I tested out 3 days old front tires with new rears and unfortunately got a lot of understeer as expected.
This day I tested out 3 days old front tires with new rears and unfortunately got a lot of understeer as expected.
10-31-2016, 12:35 PM
#923
Rennlist Member
Thread Starter
^^ Thanks Deacon, forgot my long pants so this is all I could find ;-)
VBox is a work in progress. Already found a little time just by gauging predictive times out of the corners, had to stuff the microphone under the seat cushion and need to complete the install with the rest of the data available, etc.
Look forward to just comparing V Min and exit speeds as the tires wear out.
Then back to some coaching to find a bit more time and sharpen up my driving again.
VBox is a work in progress. Already found a little time just by gauging predictive times out of the corners, had to stuff the microphone under the seat cushion and need to complete the install with the rest of the data available, etc.
Look forward to just comparing V Min and exit speeds as the tires wear out.
Then back to some coaching to find a bit more time and sharpen up my driving again.
10-31-2016, 12:58 PM
#924
Rennlist Member
Those speeds are crazy compared to my GT4 from Winterfest last year. Nice work!
10-31-2016, 01:08 PM
#925
Rennlist Member
Thread Starter
Well, the front tires were slow and my driving not great so the car had a 2:17 in it, about a second off the pace only compared to cooler Winterfest laps but we had a 17!! MPH tail wind down the back straight and that made up for the rest of the lap being slowish.
10-31-2016, 02:10 PM
#926
Rennlist
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Pete
Power. Lots is good, more is better, too much is just right...
'87 951, RIP
'00 996 C2 L92U AQ / IXAA IXRB IX54 M96/7.xx G96/7.88 M030 M375 M376 M436 M476 M601 M983 ... + 991 GT3 brakes, 997 GT3 sway bars, fully monoball'd suspension, Bilstein Cup Car coilovers, do88 Big Pack ICs. 10 & 12 x 19" BBS CH-R wheels with 265/30 & 325 /30 -19 MPSC2s.
Pete
Power. Lots is good, more is better, too much is just right...
'87 951, RIP
'00 996 C2 L92U AQ / IXAA IXRB IX54 M96/7.xx G96/7.88 M030 M375 M376 M436 M476 M601 M983 ... + 991 GT3 brakes, 997 GT3 sway bars, fully monoball'd suspension, Bilstein Cup Car coilovers, do88 Big Pack ICs. 10 & 12 x 19" BBS CH-R wheels with 265/30 & 325 /30 -19 MPSC2s.
10-31-2016, 10:33 PM
#928
Rennlist Member
2 laps Sebring playing with setup and Vbox. Both work in progress.
This day I tested out 3 days old front tires with new rears and unfortunately got a lot of understeer as expected.
https://youtu.be/0cGFOGQWeWc
This day I tested out 3 days old front tires with new rears and unfortunately got a lot of understeer as expected.
https://youtu.be/0cGFOGQWeWc
Does the VBOX allow you to adjust the brightness? With the bright sun it is hard to see the track in some places. I'd go darker in the interior in order to bring down the brightness outside.
10-31-2016, 10:51 PM
#929
Rennlist Member
Thread Starter
Work in progress. It's supposed to have 2 HD cameras.
One out the windshield and one on the driver. I tried one to see if I could save on the data as one run is more than 2 GB.
With 2 cameras the exposure is fixed but we can adjust the cameras.
Racelogic is still sorting out some data, they have it all for the GT3 but not yet for RS, I want oil and water temps, gear, RPM, G force ball like on the dash etc.
I hope by next week to have it all more permanently installed with a nice scene, like I had in my 4.0. This was just thrown in quick but I'm working on a VBox RS setup that includes software for easy .Avi editing, ideal microphone install and everything permanently installed so it starts recording when I get in the car and I can just grab the SD card, quick cut and edit and load to YouTube.
As soon as I play with it a bit I'll hire a coach to re-teach the data analisis and find a little time at Sebring.
But even now just with predictive laptimes it's teaching me what works and what doesn't in the 991. You can see the nicer scene if you search TRAKCAR 4.0 Sebring 217.4 on YouTube.
One out the windshield and one on the driver. I tried one to see if I could save on the data as one run is more than 2 GB.
With 2 cameras the exposure is fixed but we can adjust the cameras.
Racelogic is still sorting out some data, they have it all for the GT3 but not yet for RS, I want oil and water temps, gear, RPM, G force ball like on the dash etc.
I hope by next week to have it all more permanently installed with a nice scene, like I had in my 4.0. This was just thrown in quick but I'm working on a VBox RS setup that includes software for easy .Avi editing, ideal microphone install and everything permanently installed so it starts recording when I get in the car and I can just grab the SD card, quick cut and edit and load to YouTube.
As soon as I play with it a bit I'll hire a coach to re-teach the data analisis and find a little time at Sebring.
But even now just with predictive laptimes it's teaching me what works and what doesn't in the 991. You can see the nicer scene if you search TRAKCAR 4.0 Sebring 217.4 on YouTube.
