Dundon DSC test
04-26-2017, 04:09 PM
#1
Rennlist Member
Thread Starter
Dundon DSC test
Dundon (Home of the superfast headers LOL) reached out a few weeks ago and asked me to test a DSC box at Sebring.
I have 1000’s of laps at Sebring and it is a suspension track.
I’m also pretty consistent in lap times so they deemed me a good test rabbit and wanted to know what I thought of it on an otherwise stock RS (Dundon Gurney, Fabspeed side muffler delete is all).
I will try to explain from a DE drover point of view, so bear with me through my long rambling as I try to explain the 2 test days with the DSC box that Dundon sent me.
Full disclosure, I am zero technical and was not even really sure how it works or what it was supposed to do, Jamie sent me the box from Dundon and this video:
and told me to go try it at Sebring and report back.
Now that I two track days behind me, I’ve read up a bit on Rennlist here and there because it’s exciting stuff, especially if you have a shop that understands it well and can make changes to your liking, your car, your local track etc.
There’s much more stuff here from smarter people and better drivers:
https://rennlist.com/forums/997-gt2-...stalled-2.html
https://rennlist.com/forums/997-gt2-...ion-forum.html
https://rennlist.com/forums/991/8952...-module-3.html
I couldn’t find anything on the 991 GT3 / RS forum.
TIRES:
I need to give some detail about the performance degradation of the MPSC2’s because it made testing more difficult.
The first test day with the DSC box was the second day on the MPSC2 tires. It was not too hot.
The second test day last weekend it was the third day on the MPSC2 tires and it was mid 70’s to mid 90’s by the end of the day.
On the last test day this weekend, between tire degradation between sessions (and as the laps pile on) and ambient temperature increase my lap times went from 2:16’s to 2:19’s.
My TBL in 5 sessions increased and increased:
2:167 9am
2:173 10:30am
2:178 1pm (Deflated tires 2 psi too much)
2:174 2:30pm
2:183 4pm
The problem with MPSC2 is that you have to start at 26PSI all around in the GT3RS.
2 reasons:
The TPMS doesn’t “take” at 25 PSI and below so you keep getting warnings. Not even in Circuit setting, which is idiotic.
If starting too low it takes too long and you have to beat on the tires while underinflated killing the outer edge to get the PSI up and by the time they are up to 30PSI on lap 4 the tires are already overheated and get greasy.
That’s the next issue with these tires, they are only fast for 4 laps on a hot day and maybe 6 laps on a cooler Florida day. On cold days in Europe I felt very little change.
The tires are fastest on the out lap and lap 1, 2 and 3. In order to set a one lap wonder lap record, just go out on 28PSI and go ***** out on the first flyer, it probably can’t be matched the rest of the session in 80F+.
My last session at 4PM I ran 14 laps and I could only do 2:19’s with a 997 3.8RS on my *** on Hoosier R7. Lost about 2 seconds in 14 laps.
The 997 was well driven and he was so much faster in the corners, I was surely annoying him holding him up in the corners and then squirting away on the straights….Sorry!
I figure a 997 3.8RS on R7 will do 2:16-2:17 on a good day but the Hoosier R7 are much less affected by heat performance loss.
My rear tires where just about corded on the outer edge after the last session. Fronts are fine. See Photo’s below.
I have learned that even if I can make the MPSC2 rears cord later they are heat cycled out after 4 days anyway.
If I only change rear tires the car will understeer enough to be slow, so I am resigned to 4 new tires every 4 days.
Sometimes it needs to be 3, as you can see there’s not much life in the rears left.
SETUP:
Same setup I have run most of last and all of this year at Sebring mostly. Just a couple days at Homestead and PBIR.
Toe 0F -1.5mm ea side R
Camber -2F -2R
Sway bars full stiff.
Ride height and rake, as recommended for track setup by Porsche (15 page recommendation document below) minus one turn down both front and rear.
Note: I have run toe out front, I have run a lot more camber up to -3 and tried sway bars all over the place.
I found that more camber offers no better performance and doesn’t help the (rear) tires cord later. I think this is due to the tire construction where all the grip is on the outer edge.
My sway bars were full stiff to get the tires to last more than 2 days but I like bars on medium better for handeling but in the fast corners it just leaned over too much with the OEM PASM box, even in sport setting.
TESTING THE DSC BOX
I would have liked to swap the OEM PASM box with the DSC active box back to back, but I’m not exactly built like a gazelle and with a pinched nerve in my neck I just couldn’t get back there to swap boxes on track with all the scaffolding back there.
Tried it and still in pain and numbness in fingers and arm 5 days later. Now we have a cable coming to the front of the cabin if Dundon wants to experiment more, but I need a gnome to swap the DSC box for the OEM box.
On the other hand, I went out the first DSC test day and I could immediately tell it was working the first test day, just not how much exactly in each sector yet without gnome.
There was much less roll, pitch (Not enough) and squat. I didn’t want to swap OEM PASM box VS DSC PASM box anyway because it’s NICE!
The 991RS is very soft (Drives like a Caddy in comfort setting IMHO, its softer then my 2014 E63AMG), due to soft springs it leans too much.
The lean was mitigated and evident right away with the DSC box, leading me to believe that the RS could now go back to medium / middle sway bar settings and still not kill the tires in two days.
This was already suggested by Dundon, so we changed for the second test day last weekend.
The PASM button on the center console still works between comfort and sport, and with the DSC box, it remains always stays active in both settings over a larger range than OEM.
In comfort, on the road I don’t feel anything, perhaps the steering is a little more nervous as one corner of the car adjusts but that may be in my head only. Minimal if anything.
In a way the DSC box acts like stiffer springs without the negatives on the road or track is my take.
Also; Some reported on Rennlist that they couldn’t feel a difference but it seems they had other mods, like stiffer springs and in a way they do the same so I can see why those report little or no lap time improvement.
It’s a GT4 and RS thing perhaps as they seem softer sprung than any GT3 prior. They sure are comfy on the road
On the other hand on non GT cars the difference must be huge because it all feels pretty boaty to me..
The first test day with the bars in stiff I noticed that the tire wear was less.
Also different wear, somehow the MPSC2 got polished on the whole shoulder instead of grooving and chunking it on the very edge only. This was another reason I thought we could get away with softer sway bar settings.
I drove the car in comfort and in sport. I liked how the car stopped in comfort but I like how the car cornered in sport. So I asked Dundon to give me comfort setting under braking and sport setting under cornering. They changed the settings for my liking / Sebring and sent me another file.
Put the sway bars to medium and went back for the second test day last Saturday.
The last test day last weekend was difficult to do due to increasing ambient temperature, humidity, wind and tire degradation mentioned above my laps times dropped a lot as mentioned above.
There were also a few black flags.
When Corvettes sign up, they should give everyone else a 25% discount as that is typically how much track time we lose by them oiling the track and getting flat bedded off.
My plan was 3-4 laps comfort, 3-4 laps in sport etc. but a few times I only got 3-4 laps. But even when we got a lot more laps after lap 4 the MPSC2’s are crap over 80F, so its hard to feel the difference.
But After every session I looked at differences in sector times and it proved that what I felt resulted in purple sector times, even after lap 4 with the tires cooked.
FINDIGS AND THOUGHTS:
Cloudspin, a fellow Rennlister was there also on the same day and he has been running a DSC box for a while beating hard on his 997 as well with good results.
His 997 and my 991RS are not the same, so I think in principle the change we noticed is the same but how they apply to better sector times will very between cars and drivers.
So what I found may be due to my driving style and the RS handling characteristics.
After Dundon gave me the settings I asked for, I could stop the car much better in sport setting, much easier to stay out of ABS and get the front tires to grab. Advantage clearly into T3, T7, T10, T15, easy to feel and shows in sector times.
When the car was stiff under braking it felt like a car that was lowered too much, I couldn’t transfer the weight to the front and it felt like the car was skipping over the asphalt instead of “digging in”. I did a few Oh ****, oh ****, oh **** full on stops and the braking was awesome.
Because the car was softer under braking, the nose went lower and the tail went higher, it required a bit more precision coming off the brakes when trail braking to keep the rear in line. But when I went to comfort setting, those same corners needed too much time coming off the brakes, so the sport setting helped.
The car in sport was a lot more confidence inspiring in the fast corners in sport setting, I actually had to pay attention because I was going so much faster into and through T1, Bishop, T17..
This is huge, even if ultimate speed isn’t much faster around the track.
There is a little less feel because the shocks are stiffer and its takes a bit more paying attention to feel what the car is doing and where the grip is.
In sport it was easier to squirt out of a couple of corners because the rear was more flat and so less grippy out of the slower corners. This helped going for throttle earlier as I was able to mitigate the understeer by throttle. T5 and T16.
Where sport was slower was into and out of T7. The car stopped great for the hairpin but the rear was a bit too stiff and I got too much wheel spin and there’s a long straight after T7 but I was able to almost completely drive around it. The softer sway bars helped here.
Ideally they make this a continues variable box based on GPS coordinates LOL.
But that just shows that if an amateur drover like me THINKS I can pin-point what I want it to do and for what corner, it works….But just like double adjustable shocks, I would probably make a mess of it because I don’t know how and I can’t afford to approach it like the Pro’s.
What’s cool is that in comfort, the car is still feels better than OEM.
Overall the sport setting gave me more confidence. I think the DSC box is good for at least a second per lap at Sebring and in some conditions even more, but I won’t be able to prove it until I go back on new tires on a cold morning.
It could be that a pro just is skilled enough to get the same lap times out of the OEM box VS the DSC box. In the end the tire is the tire but when I want to get a 2:15 out of the car OEM, I need to nail every corner, JUST SO.. While with the active box the car is much more composed at a minimum.
On both days I drove on not new tires on not very cool weather 2:17’s so I think it’s a second at least with my previous personal best being 2:159 on new tires, pads and a cool day!
It also allows me to play with the sway bars again without killing the MPSC2’s and/or get more life out of the rear tires.
That’s all I got for now!
I’d love other 991 GT3’s and RS post feedback on it here once they try it!
I have 1000’s of laps at Sebring and it is a suspension track.
I’m also pretty consistent in lap times so they deemed me a good test rabbit and wanted to know what I thought of it on an otherwise stock RS (Dundon Gurney, Fabspeed side muffler delete is all).
I will try to explain from a DE drover point of view, so bear with me through my long rambling as I try to explain the 2 test days with the DSC box that Dundon sent me.
Full disclosure, I am zero technical and was not even really sure how it works or what it was supposed to do, Jamie sent me the box from Dundon and this video:
Now that I two track days behind me, I’ve read up a bit on Rennlist here and there because it’s exciting stuff, especially if you have a shop that understands it well and can make changes to your liking, your car, your local track etc.
There’s much more stuff here from smarter people and better drivers:
https://rennlist.com/forums/997-gt2-...stalled-2.html
https://rennlist.com/forums/997-gt2-...ion-forum.html
https://rennlist.com/forums/991/8952...-module-3.html
I couldn’t find anything on the 991 GT3 / RS forum.
TIRES:
I need to give some detail about the performance degradation of the MPSC2’s because it made testing more difficult.
The first test day with the DSC box was the second day on the MPSC2 tires. It was not too hot.
The second test day last weekend it was the third day on the MPSC2 tires and it was mid 70’s to mid 90’s by the end of the day.
On the last test day this weekend, between tire degradation between sessions (and as the laps pile on) and ambient temperature increase my lap times went from 2:16’s to 2:19’s.
My TBL in 5 sessions increased and increased:
2:167 9am
2:173 10:30am
2:178 1pm (Deflated tires 2 psi too much)
2:174 2:30pm
2:183 4pm
The problem with MPSC2 is that you have to start at 26PSI all around in the GT3RS.
2 reasons:
The TPMS doesn’t “take” at 25 PSI and below so you keep getting warnings. Not even in Circuit setting, which is idiotic.
If starting too low it takes too long and you have to beat on the tires while underinflated killing the outer edge to get the PSI up and by the time they are up to 30PSI on lap 4 the tires are already overheated and get greasy.
That’s the next issue with these tires, they are only fast for 4 laps on a hot day and maybe 6 laps on a cooler Florida day. On cold days in Europe I felt very little change.
The tires are fastest on the out lap and lap 1, 2 and 3. In order to set a one lap wonder lap record, just go out on 28PSI and go ***** out on the first flyer, it probably can’t be matched the rest of the session in 80F+.
My last session at 4PM I ran 14 laps and I could only do 2:19’s with a 997 3.8RS on my *** on Hoosier R7. Lost about 2 seconds in 14 laps.
The 997 was well driven and he was so much faster in the corners, I was surely annoying him holding him up in the corners and then squirting away on the straights….Sorry!
I figure a 997 3.8RS on R7 will do 2:16-2:17 on a good day but the Hoosier R7 are much less affected by heat performance loss.
My rear tires where just about corded on the outer edge after the last session. Fronts are fine. See Photo’s below.
I have learned that even if I can make the MPSC2 rears cord later they are heat cycled out after 4 days anyway.
If I only change rear tires the car will understeer enough to be slow, so I am resigned to 4 new tires every 4 days.
Sometimes it needs to be 3, as you can see there’s not much life in the rears left.
SETUP:
Same setup I have run most of last and all of this year at Sebring mostly. Just a couple days at Homestead and PBIR.
Toe 0F -1.5mm ea side R
Camber -2F -2R
Sway bars full stiff.
Ride height and rake, as recommended for track setup by Porsche (15 page recommendation document below) minus one turn down both front and rear.
Note: I have run toe out front, I have run a lot more camber up to -3 and tried sway bars all over the place.
I found that more camber offers no better performance and doesn’t help the (rear) tires cord later. I think this is due to the tire construction where all the grip is on the outer edge.
My sway bars were full stiff to get the tires to last more than 2 days but I like bars on medium better for handeling but in the fast corners it just leaned over too much with the OEM PASM box, even in sport setting.
TESTING THE DSC BOX
I would have liked to swap the OEM PASM box with the DSC active box back to back, but I’m not exactly built like a gazelle and with a pinched nerve in my neck I just couldn’t get back there to swap boxes on track with all the scaffolding back there.
Tried it and still in pain and numbness in fingers and arm 5 days later. Now we have a cable coming to the front of the cabin if Dundon wants to experiment more, but I need a gnome to swap the DSC box for the OEM box.
On the other hand, I went out the first DSC test day and I could immediately tell it was working the first test day, just not how much exactly in each sector yet without gnome.
There was much less roll, pitch (Not enough) and squat. I didn’t want to swap OEM PASM box VS DSC PASM box anyway because it’s NICE!
The 991RS is very soft (Drives like a Caddy in comfort setting IMHO, its softer then my 2014 E63AMG), due to soft springs it leans too much.
The lean was mitigated and evident right away with the DSC box, leading me to believe that the RS could now go back to medium / middle sway bar settings and still not kill the tires in two days.
This was already suggested by Dundon, so we changed for the second test day last weekend.
The PASM button on the center console still works between comfort and sport, and with the DSC box, it remains always stays active in both settings over a larger range than OEM.
In comfort, on the road I don’t feel anything, perhaps the steering is a little more nervous as one corner of the car adjusts but that may be in my head only. Minimal if anything.
In a way the DSC box acts like stiffer springs without the negatives on the road or track is my take.
Also; Some reported on Rennlist that they couldn’t feel a difference but it seems they had other mods, like stiffer springs and in a way they do the same so I can see why those report little or no lap time improvement.
It’s a GT4 and RS thing perhaps as they seem softer sprung than any GT3 prior. They sure are comfy on the road
On the other hand on non GT cars the difference must be huge because it all feels pretty boaty to me..
The first test day with the bars in stiff I noticed that the tire wear was less.
Also different wear, somehow the MPSC2 got polished on the whole shoulder instead of grooving and chunking it on the very edge only. This was another reason I thought we could get away with softer sway bar settings.
I drove the car in comfort and in sport. I liked how the car stopped in comfort but I like how the car cornered in sport. So I asked Dundon to give me comfort setting under braking and sport setting under cornering. They changed the settings for my liking / Sebring and sent me another file.
Put the sway bars to medium and went back for the second test day last Saturday.
The last test day last weekend was difficult to do due to increasing ambient temperature, humidity, wind and tire degradation mentioned above my laps times dropped a lot as mentioned above.
There were also a few black flags.
When Corvettes sign up, they should give everyone else a 25% discount as that is typically how much track time we lose by them oiling the track and getting flat bedded off.
My plan was 3-4 laps comfort, 3-4 laps in sport etc. but a few times I only got 3-4 laps. But even when we got a lot more laps after lap 4 the MPSC2’s are crap over 80F, so its hard to feel the difference.
But After every session I looked at differences in sector times and it proved that what I felt resulted in purple sector times, even after lap 4 with the tires cooked.
FINDIGS AND THOUGHTS:
Cloudspin, a fellow Rennlister was there also on the same day and he has been running a DSC box for a while beating hard on his 997 as well with good results.
His 997 and my 991RS are not the same, so I think in principle the change we noticed is the same but how they apply to better sector times will very between cars and drivers.
So what I found may be due to my driving style and the RS handling characteristics.
After Dundon gave me the settings I asked for, I could stop the car much better in sport setting, much easier to stay out of ABS and get the front tires to grab. Advantage clearly into T3, T7, T10, T15, easy to feel and shows in sector times.
When the car was stiff under braking it felt like a car that was lowered too much, I couldn’t transfer the weight to the front and it felt like the car was skipping over the asphalt instead of “digging in”. I did a few Oh ****, oh ****, oh **** full on stops and the braking was awesome.
Because the car was softer under braking, the nose went lower and the tail went higher, it required a bit more precision coming off the brakes when trail braking to keep the rear in line. But when I went to comfort setting, those same corners needed too much time coming off the brakes, so the sport setting helped.
The car in sport was a lot more confidence inspiring in the fast corners in sport setting, I actually had to pay attention because I was going so much faster into and through T1, Bishop, T17..
This is huge, even if ultimate speed isn’t much faster around the track.
There is a little less feel because the shocks are stiffer and its takes a bit more paying attention to feel what the car is doing and where the grip is.
In sport it was easier to squirt out of a couple of corners because the rear was more flat and so less grippy out of the slower corners. This helped going for throttle earlier as I was able to mitigate the understeer by throttle. T5 and T16.
Where sport was slower was into and out of T7. The car stopped great for the hairpin but the rear was a bit too stiff and I got too much wheel spin and there’s a long straight after T7 but I was able to almost completely drive around it. The softer sway bars helped here.
Ideally they make this a continues variable box based on GPS coordinates LOL.
But that just shows that if an amateur drover like me THINKS I can pin-point what I want it to do and for what corner, it works….But just like double adjustable shocks, I would probably make a mess of it because I don’t know how and I can’t afford to approach it like the Pro’s.
What’s cool is that in comfort, the car is still feels better than OEM.
Overall the sport setting gave me more confidence. I think the DSC box is good for at least a second per lap at Sebring and in some conditions even more, but I won’t be able to prove it until I go back on new tires on a cold morning.
It could be that a pro just is skilled enough to get the same lap times out of the OEM box VS the DSC box. In the end the tire is the tire but when I want to get a 2:15 out of the car OEM, I need to nail every corner, JUST SO.. While with the active box the car is much more composed at a minimum.
On both days I drove on not new tires on not very cool weather 2:17’s so I think it’s a second at least with my previous personal best being 2:159 on new tires, pads and a cool day!
It also allows me to play with the sway bars again without killing the MPSC2’s and/or get more life out of the rear tires.
That’s all I got for now!
I’d love other 991 GT3’s and RS post feedback on it here once they try it!
04-26-2017, 04:53 PM
#3
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Gotta have it! Peter is a great test Rabbit for sure. Bumpiest most punishing track we could think of and really working to help DSCSport get the word out on really how good and revolutionary the DSCSport controller really is!
__________________
Dundon Motorsports
Gig Harbor, WA
253-200-4454
jamie@dundonmotorsports.com
www.dundonmotorsports.com
Facebook.com/dundonmotorsports
Instagram @dundon_motorsports
Dundon Motorsports
Gig Harbor, WA
253-200-4454
jamie@dundonmotorsports.com
www.dundonmotorsports.com
Facebook.com/dundonmotorsports
Instagram @dundon_motorsports
04-26-2017, 05:40 PM
#5
Thanks for the review.
I had one on my 997 GTS and have one sitting here waiting to go in the 991GT3, it arrived last week from another well known member on here. The car is being picked up for some warranty work tomorrow though so haven't tried it yet.
It was great on the 997, so hoping for good things on the 991 as we have some bumpy roads here.
Regards
Fred
I had one on my 997 GTS and have one sitting here waiting to go in the 991GT3, it arrived last week from another well known member on here. The car is being picked up for some warranty work tomorrow though so haven't tried it yet.
It was great on the 997, so hoping for good things on the 991 as we have some bumpy roads here.
Regards
Fred
04-26-2017, 05:40 PM
#6
Dundon (Home of the superfast headers LOL) reached out a few weeks ago and asked me to test a DSC box at Sebring.
I have 1000’s of laps at Sebring and it is a suspension track.
I’m also pretty consistent in lap times so they deemed me a good test rabbit and wanted to know what I thought of it on an otherwise stock RS (Dundon Gurney, Fabspeed side muffler delete is all).
I will try to explain from a DE drover point of view, so bear with me through my long rambling as I try to explain the 2 test days with the DSC box that Dundon sent me.
Full disclosure, I am zero technical and was not even really sure how it works or what it was supposed to do, Jamie sent me the box from Dundon and this video: https://www.youtube.com/watch?v=K-SngddJKls and told me to go try it at Sebring and report back.
Now that I two track days behind me, I’ve read up a bit on Rennlist here and there because it’s exciting stuff, especially if you have a shop that understands it well and can make changes to your liking, your car, your local track etc.
There’s much more stuff here from smarter people and better drivers:
https://rennlist.com/forums/997-gt2-...stalled-2.html
https://rennlist.com/forums/997-gt2-...ion-forum.html
https://rennlist.com/forums/991/8952...-module-3.html
I couldn’t find anything on the 991 GT3 / RS forum.
TIRES:
I need to give some detail about the performance degradation of the MPSC2’s because it made testing more difficult.
The first test day with the DSC box was the second day on the MPSC2 tires. It was not too hot.
The second test day last weekend it was the third day on the MPSC2 tires and it was mid 70’s to mid 90’s by the end of the day.
On the last test day this weekend, between tire degradation between sessions (and as the laps pile on) and ambient temperature increase my lap times went from 2:16’s to 2:19’s.
My TBL in 5 sessions increased and increased:
2:167 9am
2:173 10:30am
2:178 1pm (Deflated tires 2 psi too much)
2:174 2:30pm
2:183 4pm
The problem with MPSC2 is that you have to start at 26PSI all around in the GT3RS.
2 reasons:
The TPMS doesn’t “take” at 25 PSI and below so you keep getting warnings. Not even in Circuit setting, which is idiotic.
If starting too low it takes too long and you have to beat on the tires while underinflated killing the outer edge to get the PSI up and by the time they are up to 30PSI on lap 4 the tires are already overheated and get greasy.
That’s the next issue with these tires, they are only fast for 4 laps on a hot day and maybe 6 laps on a cooler Florida day. On cold days in Europe I felt very little change.
The tires are fastest on the out lap and lap 1, 2 and 3. In order to set a one lap wonder lap record, just go out on 28PSI and go ***** out on the first flyer, it probably can’t be matched the rest of the session in 80F+.
My last session at 4PM I ran 14 laps and I could only do 2:19’s with a 997 3.8RS on my *** on Hoosier R7. Lost about 2 seconds in 14 laps.
The 997 was well driven and he was so much faster in the corners, I was surely annoying him holding him up in the corners and then squirting away on the straights….Sorry!
I figure a 997 3.8RS on R7 will do 2:16-2:17 on a good day but the Hoosier R7 are much less affected by heat performance loss.
My rear tires where just about corded on the outer edge after the last session. Fronts are fine. See Photo’s below.
I have learned that even if I can make the MPSC2 rears cord later they are heat cycled out after 4 days anyway.
If I only change rear tires the car will understeer enough to be slow, so I am resigned to 4 new tires every 4 days.
Sometimes it needs to be 3, as you can see there’s not much life in the rears left.
SETUP:
Same setup I have run most of last and all of this year at Sebring mostly. Just a couple days at Homestead and PBIR.
Toe 0F -1.5mm ea side R
Camber -2F -2R
Sway bars full stiff.
Ride height and rake, as recommended for track setup by Porsche (15 page recommendation document below) minus one turn down both front and rear.
Note: I have run toe out front, I have run a lot more camber up to -3 and tried sway bars all over the place.
I found that more camber offers no better performance and doesn’t help the (rear) tires cord later. I think this is due to the tire construction where all the grip is on the outer edge.
My sway bars were full stiff to get the tires to last more than 2 days but I like bars on medium better for handeling but in the fast corners it just leaned over too much with the OEM PASM box, even in sport setting.
TESTING THE DSC BOX
I would have liked to swap the OEM PASM box with the DSC active box back to back, but I’m not exactly built like a gazelle and with a pinched nerve in my neck I just couldn’t get back there to swap boxes on track with all the scaffolding back there.
Tried it and still in pain and numbness in fingers and arm 5 days later. Now we have a cable coming to the front of the cabin if Dundon wants to experiment more, but I need a gnome to swap the DSC box for the OEM box.
On the other hand, I went out the first DSC test day and I could immediately tell it was working the first test day, just not how much exactly in each sector yet without gnome.
There was much less roll, pitch (Not enough) and squat. I didn’t want to swap OEM PASM box VS DSC PASM box anyway because it’s NICE!
The 991RS is very soft (Drives like a Caddy in comfort setting IMHO, its softer then my 2014 E63AMG), due to soft springs it leans too much.
The lean was mitigated and evident right away with the DSC box, leading me to believe that the RS could now go back to medium / middle sway bar settings and still not kill the tires in two days.
This was already suggested by Dundon, so we changed for the second test day last weekend.
The PASM button on the center console still works between comfort and sport, and with the DSC box, it remains always stays active in both settings over a larger range than OEM.
In comfort, on the road I don’t feel anything, perhaps the steering is a little more nervous as one corner of the car adjusts but that may be in my head only. Minimal if anything.
In a way the DSC box acts like stiffer springs without the negatives on the road or track is my take.
Also; Some reported on Rennlist that they couldn’t feel a difference but it seems they had other mods, like stiffer springs and in a way they do the same so I can see why those report little or no lap time improvement.
It’s a GT4 and RS thing perhaps as they seem softer sprung than any GT3 prior. They sure are comfy on the road
On the other hand on non GT cars the difference must be huge because it all feels pretty boaty to me..
The first test day with the bars in stiff I noticed that the tire wear was less.
Also different wear, somehow the MPSC2 got polished on the whole shoulder instead of grooving and chunking it on the very edge only. This was another reason I thought we could get away with softer sway bar settings.
I drove the car in comfort and in sport. I liked how the car stopped in comfort but I like how the car cornered in sport. So I asked Dundon to give me comfort setting under braking and sport setting under cornering. They changed the settings for my liking / Sebring and sent me another file.
Put the sway bars to medium and went back for the second test day last Saturday.
The last test day last weekend was difficult to do due to increasing ambient temperature, humidity, wind and tire degradation mentioned above my laps times dropped a lot as mentioned above.
There were also a few black flags.
When Corvettes sign up, they should give everyone else a 25% discount as that is typically how much track time we lose by them oiling the track and getting flat bedded off.
My plan was 3-4 laps comfort, 3-4 laps in sport etc. but a few times I only got 3-4 laps. But even when we got a lot more laps after lap 4 the MPSC2’s are crap over 80F, so its hard to feel the difference.
But After every session I looked at differences in sector times and it proved that what I felt resulted in purple sector times, even after lap 4 with the tires cooked.
FINDIGS AND THOUGHTS:
Cloudspin, a fellow Rennlister was there also on the same day and he has been running a DSC box for a while beating hard on his 997 as well with good results.
His 997 and my 991RS are not the same, so I think in principle the change we noticed is the same but how they apply to better sector times will very between cars and drivers.
So what I found may be due to my driving style and the RS handling characteristics.
After Dundon gave me the settings I asked for, I could stop the car much better in sport setting, much easier to stay out of ABS and get the front tires to grab. Advantage clearly into T3, T7, T10, T15, easy to feel and shows in sector times.
When the car was stiff under braking it felt like a car that was lowered too much, I couldn’t transfer the weight to the front and it felt like the car was skipping over the asphalt instead of “digging in”. I did a few Oh ****, oh ****, oh **** full on stops and the braking was awesome.
Because the car was softer under braking, the nose went lower and the tail went higher, it required a bit more precision coming off the brakes when trail braking to keep the rear in line. But when I went to comfort setting, those same corners needed too much time coming off the brakes, so the sport setting helped.
The car in sport was a lot more confidence inspiring in the fast corners in sport setting, I actually had to pay attention because I was going so much faster into and through T1, Bishop, T17..
This is huge, even if ultimate speed isn’t much faster around the track.
There is a little less feel because the shocks are stiffer and its takes a bit more paying attention to feel what the car is doing and where the grip is.
In sport it was easier to squirt out of a couple of corners because the rear was more flat and so less grippy out of the slower corners. This helped going for throttle earlier as I was able to mitigate the understeer by throttle. T5 and T16.
Where sport was slower was into and out of T7. The car stopped great for the hairpin but the rear was a bit too stiff and I got too much wheel spin and there’s a long straight after T7 but I was able to almost completely drive around it. The softer sway bars helped here.
Ideally they make this a continues variable box based on GPS coordinates LOL.
But that just shows that if an amateur drover like me THINKS I can pin-point what I want it to do and for what corner, it works….But just like double adjustable shocks, I would probably make a mess of it because I don’t know how and I can’t afford to approach it like the Pro’s.
What’s cool is that in comfort, the car is still feels better than OEM.
Overall the sport setting gave me more confidence. I think the DSC box is good for at least a second per lap at Sebring and in some conditions even more, but I won’t be able to prove it until I go back on new tires on a cold morning.
It could be that a pro just is skilled enough to get the same lap times out of the OEM box VS the DSC box. In the end the tire is the tire but when I want to get a 2:15 out of the car OEM, I need to nail every corner, JUST SO.. While with the active box the car is much more composed at a minimum.
On both days I drove on not new tires on not very cool weather 2:17’s so I think it’s a second at least with my previous personal best being 2:159 on new tires, pads and a cool day!
It also allows me to play with the sway bars again without killing the MPSC2’s and/or get more life out of the rear tires.
That’s all I got for now!
I’d love other 991 GT3’s and RS post feedback on it here once they try it!
I have 1000’s of laps at Sebring and it is a suspension track.
I’m also pretty consistent in lap times so they deemed me a good test rabbit and wanted to know what I thought of it on an otherwise stock RS (Dundon Gurney, Fabspeed side muffler delete is all).
I will try to explain from a DE drover point of view, so bear with me through my long rambling as I try to explain the 2 test days with the DSC box that Dundon sent me.
Full disclosure, I am zero technical and was not even really sure how it works or what it was supposed to do, Jamie sent me the box from Dundon and this video: https://www.youtube.com/watch?v=K-SngddJKls and told me to go try it at Sebring and report back.
Now that I two track days behind me, I’ve read up a bit on Rennlist here and there because it’s exciting stuff, especially if you have a shop that understands it well and can make changes to your liking, your car, your local track etc.
There’s much more stuff here from smarter people and better drivers:
https://rennlist.com/forums/997-gt2-...stalled-2.html
https://rennlist.com/forums/997-gt2-...ion-forum.html
https://rennlist.com/forums/991/8952...-module-3.html
I couldn’t find anything on the 991 GT3 / RS forum.
TIRES:
I need to give some detail about the performance degradation of the MPSC2’s because it made testing more difficult.
The first test day with the DSC box was the second day on the MPSC2 tires. It was not too hot.
The second test day last weekend it was the third day on the MPSC2 tires and it was mid 70’s to mid 90’s by the end of the day.
On the last test day this weekend, between tire degradation between sessions (and as the laps pile on) and ambient temperature increase my lap times went from 2:16’s to 2:19’s.
My TBL in 5 sessions increased and increased:
2:167 9am
2:173 10:30am
2:178 1pm (Deflated tires 2 psi too much)
2:174 2:30pm
2:183 4pm
The problem with MPSC2 is that you have to start at 26PSI all around in the GT3RS.
2 reasons:
The TPMS doesn’t “take” at 25 PSI and below so you keep getting warnings. Not even in Circuit setting, which is idiotic.
If starting too low it takes too long and you have to beat on the tires while underinflated killing the outer edge to get the PSI up and by the time they are up to 30PSI on lap 4 the tires are already overheated and get greasy.
That’s the next issue with these tires, they are only fast for 4 laps on a hot day and maybe 6 laps on a cooler Florida day. On cold days in Europe I felt very little change.
The tires are fastest on the out lap and lap 1, 2 and 3. In order to set a one lap wonder lap record, just go out on 28PSI and go ***** out on the first flyer, it probably can’t be matched the rest of the session in 80F+.
My last session at 4PM I ran 14 laps and I could only do 2:19’s with a 997 3.8RS on my *** on Hoosier R7. Lost about 2 seconds in 14 laps.
The 997 was well driven and he was so much faster in the corners, I was surely annoying him holding him up in the corners and then squirting away on the straights….Sorry!
I figure a 997 3.8RS on R7 will do 2:16-2:17 on a good day but the Hoosier R7 are much less affected by heat performance loss.
My rear tires where just about corded on the outer edge after the last session. Fronts are fine. See Photo’s below.
I have learned that even if I can make the MPSC2 rears cord later they are heat cycled out after 4 days anyway.
If I only change rear tires the car will understeer enough to be slow, so I am resigned to 4 new tires every 4 days.
Sometimes it needs to be 3, as you can see there’s not much life in the rears left.
SETUP:
Same setup I have run most of last and all of this year at Sebring mostly. Just a couple days at Homestead and PBIR.
Toe 0F -1.5mm ea side R
Camber -2F -2R
Sway bars full stiff.
Ride height and rake, as recommended for track setup by Porsche (15 page recommendation document below) minus one turn down both front and rear.
Note: I have run toe out front, I have run a lot more camber up to -3 and tried sway bars all over the place.
I found that more camber offers no better performance and doesn’t help the (rear) tires cord later. I think this is due to the tire construction where all the grip is on the outer edge.
My sway bars were full stiff to get the tires to last more than 2 days but I like bars on medium better for handeling but in the fast corners it just leaned over too much with the OEM PASM box, even in sport setting.
TESTING THE DSC BOX
I would have liked to swap the OEM PASM box with the DSC active box back to back, but I’m not exactly built like a gazelle and with a pinched nerve in my neck I just couldn’t get back there to swap boxes on track with all the scaffolding back there.
Tried it and still in pain and numbness in fingers and arm 5 days later. Now we have a cable coming to the front of the cabin if Dundon wants to experiment more, but I need a gnome to swap the DSC box for the OEM box.
On the other hand, I went out the first DSC test day and I could immediately tell it was working the first test day, just not how much exactly in each sector yet without gnome.
There was much less roll, pitch (Not enough) and squat. I didn’t want to swap OEM PASM box VS DSC PASM box anyway because it’s NICE!
The 991RS is very soft (Drives like a Caddy in comfort setting IMHO, its softer then my 2014 E63AMG), due to soft springs it leans too much.
The lean was mitigated and evident right away with the DSC box, leading me to believe that the RS could now go back to medium / middle sway bar settings and still not kill the tires in two days.
This was already suggested by Dundon, so we changed for the second test day last weekend.
The PASM button on the center console still works between comfort and sport, and with the DSC box, it remains always stays active in both settings over a larger range than OEM.
In comfort, on the road I don’t feel anything, perhaps the steering is a little more nervous as one corner of the car adjusts but that may be in my head only. Minimal if anything.
In a way the DSC box acts like stiffer springs without the negatives on the road or track is my take.
Also; Some reported on Rennlist that they couldn’t feel a difference but it seems they had other mods, like stiffer springs and in a way they do the same so I can see why those report little or no lap time improvement.
It’s a GT4 and RS thing perhaps as they seem softer sprung than any GT3 prior. They sure are comfy on the road
On the other hand on non GT cars the difference must be huge because it all feels pretty boaty to me..
The first test day with the bars in stiff I noticed that the tire wear was less.
Also different wear, somehow the MPSC2 got polished on the whole shoulder instead of grooving and chunking it on the very edge only. This was another reason I thought we could get away with softer sway bar settings.
I drove the car in comfort and in sport. I liked how the car stopped in comfort but I like how the car cornered in sport. So I asked Dundon to give me comfort setting under braking and sport setting under cornering. They changed the settings for my liking / Sebring and sent me another file.
Put the sway bars to medium and went back for the second test day last Saturday.
The last test day last weekend was difficult to do due to increasing ambient temperature, humidity, wind and tire degradation mentioned above my laps times dropped a lot as mentioned above.
There were also a few black flags.
When Corvettes sign up, they should give everyone else a 25% discount as that is typically how much track time we lose by them oiling the track and getting flat bedded off.
My plan was 3-4 laps comfort, 3-4 laps in sport etc. but a few times I only got 3-4 laps. But even when we got a lot more laps after lap 4 the MPSC2’s are crap over 80F, so its hard to feel the difference.
But After every session I looked at differences in sector times and it proved that what I felt resulted in purple sector times, even after lap 4 with the tires cooked.
FINDIGS AND THOUGHTS:
Cloudspin, a fellow Rennlister was there also on the same day and he has been running a DSC box for a while beating hard on his 997 as well with good results.
His 997 and my 991RS are not the same, so I think in principle the change we noticed is the same but how they apply to better sector times will very between cars and drivers.
So what I found may be due to my driving style and the RS handling characteristics.
After Dundon gave me the settings I asked for, I could stop the car much better in sport setting, much easier to stay out of ABS and get the front tires to grab. Advantage clearly into T3, T7, T10, T15, easy to feel and shows in sector times.
When the car was stiff under braking it felt like a car that was lowered too much, I couldn’t transfer the weight to the front and it felt like the car was skipping over the asphalt instead of “digging in”. I did a few Oh ****, oh ****, oh **** full on stops and the braking was awesome.
Because the car was softer under braking, the nose went lower and the tail went higher, it required a bit more precision coming off the brakes when trail braking to keep the rear in line. But when I went to comfort setting, those same corners needed too much time coming off the brakes, so the sport setting helped.
The car in sport was a lot more confidence inspiring in the fast corners in sport setting, I actually had to pay attention because I was going so much faster into and through T1, Bishop, T17..
This is huge, even if ultimate speed isn’t much faster around the track.
There is a little less feel because the shocks are stiffer and its takes a bit more paying attention to feel what the car is doing and where the grip is.
In sport it was easier to squirt out of a couple of corners because the rear was more flat and so less grippy out of the slower corners. This helped going for throttle earlier as I was able to mitigate the understeer by throttle. T5 and T16.
Where sport was slower was into and out of T7. The car stopped great for the hairpin but the rear was a bit too stiff and I got too much wheel spin and there’s a long straight after T7 but I was able to almost completely drive around it. The softer sway bars helped here.
Ideally they make this a continues variable box based on GPS coordinates LOL.
But that just shows that if an amateur drover like me THINKS I can pin-point what I want it to do and for what corner, it works….But just like double adjustable shocks, I would probably make a mess of it because I don’t know how and I can’t afford to approach it like the Pro’s.
What’s cool is that in comfort, the car is still feels better than OEM.
Overall the sport setting gave me more confidence. I think the DSC box is good for at least a second per lap at Sebring and in some conditions even more, but I won’t be able to prove it until I go back on new tires on a cold morning.
It could be that a pro just is skilled enough to get the same lap times out of the OEM box VS the DSC box. In the end the tire is the tire but when I want to get a 2:15 out of the car OEM, I need to nail every corner, JUST SO.. While with the active box the car is much more composed at a minimum.
On both days I drove on not new tires on not very cool weather 2:17’s so I think it’s a second at least with my previous personal best being 2:159 on new tires, pads and a cool day!
It also allows me to play with the sway bars again without killing the MPSC2’s and/or get more life out of the rear tires.
That’s all I got for now!
I’d love other 991 GT3’s and RS post feedback on it here once they try it!
You should try more camber, - 2 is a bit low for what you are doing. Try closer to - 3, your tires will work better and heat quicker. At 25 psi start, they should be ready in 2 laps. I find 28 - 31 a good range.
Trending Topics
04-26-2017, 06:01 PM
#8
Rennlist Member
Thread Starter
Oops, I missed a few posts.
Thanks Jamie.
I tried. You wont give it back, I promise.
I hope that's for GT3 not an RS.
greed on PSI
I tried. You wont give it back, I promise.
Thanks for the review.
I had one on my 997 GTS and have one sitting here waiting to go in the 991GT3, it arrived last week from another well known member on here. The car is being picked up for some warranty work tomorrow though so haven't tried it yet.
It was great on the 997, so hoping for good things on the 991 as we have some bumpy roads here.
Regards
Fred
I had one on my 997 GTS and have one sitting here waiting to go in the 991GT3, it arrived last week from another well known member on here. The car is being picked up for some warranty work tomorrow though so haven't tried it yet.
It was great on the 997, so hoping for good things on the 991 as we have some bumpy roads here.
Regards
Fred
greed on PSI
04-26-2017, 06:05 PM
#10
Rennlist Member
Thread Starter
**** just realized I forgot to include the GT4 link.
GT4 is the new GT3 where all the track junkies are.. My bad!!
The RS is magic, but the GT4 is the best track car for the $$
GT4 is the new GT3 where all the track junkies are.. My bad!!
The RS is magic, but the GT4 is the best track car for the $$
04-27-2017, 11:04 AM
#11
Rennlist Member
Great writeup. As a DSC user myself I can totally relate to your observations. This is a great product!
04-27-2017, 02:37 PM
#12
Basic Sponsor
Rennlist
Site Sponsor
Rennlist
Site Sponsor
will be outfitting my 991 GT3 with full Tractive Dampers as soon as the next batch arrives. The added range of compression and rebound and faster reaction will be great to dial in!
04-28-2017, 09:52 AM
#13
Basic Sponsor
Rennlist
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Thank you for the detailed and complimentary write up! And a big thank you to Dundon for all the great work they've been putting in on learning, supporting, and promoting the DSC line as well!
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sales@dscsport.com | (410) 799-7798
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