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Thanks. I've driven two tracks now with the Cayman (SCCA TTNT last weekend) and PDK is pretty awesome. I've only run it in Sport Plus Auto mode. I do find the behavior sort of like: I brake into a turn and it downshifts nicely through a few gears, i apex and floor it and it holds in that gear for maybe 10 feet and then it kicks down to a lower gear and pulls out. It's sort of odd to downshift while tracking out. It hasn't actually upset the car yet, but it seems like that potential is there. Is this how it should work? If i were shifting manually, i'd be in the lowest gear at the apex so i'm already in it for tracking out.
I don't have video, but i could share some Aim canbus data if helpful.
No, that's not how it's supposed to work, and the potential to upset the car is there. Your experience illustrates the benefits of shifting the PDK manually.
By "supposed to work" i'm asking if this is expected behavior from the PDK in auto mode. Maybe i'm not doing it right. Maybe i'm not pressing hard enough on the kick down switch or something. If this is normal PDK behavior, then yeah, i'll consider manually shifting. That's the crux of my original question about if auto is used in "pro" competition. Like what are the BGB cars running IMSA doing?
By "supposed to work" i'm asking if this is expected behavior from the PDK in auto mode. Maybe i'm not doing it right. Maybe i'm not pressing hard enough on the kick down switch or something. If this is normal PDK behavior, then yeah, i'll consider manually shifting. That's the crux of my original question about if auto is used in "pro" competition. Like what are the BGB cars running IMSA doing?
It depends on the Porsche and the PDK setting. My 991.1 GT3 in auto mode doesn't do that - it downshifts during braking, not when getting back on the gas after braking. But I've seen other Porsches do what you describe.
Thanks. I've driven two tracks now with the Cayman (SCCA TTNT last weekend) and PDK is pretty awesome. I've only run it in Sport Plus Auto mode. I do find the behavior sort of like: I brake into a turn and it downshifts nicely through a few gears, i apex and floor it and it holds in that gear for maybe 10feet and then it kicks down to a lower gear and pulls out. It's sort of odd to downshift while tracking out. It hasn't actually upset the car yet, but it seems like that potential is there. Is this how it should work? If i were shifting manually, i'd be in the lowest gear at the apex so i'm already in it for tracking out.
I don't have video, but i could share some Aim canbus data if helpful.
When you say you 'floor it' you are likely hitting the kick-down switch, making it drop a gear. Better to roll on the throttle than mash the crap out of it.
Maybe the problem was worse in my head. It was most pronounced on the last turn of the track so maybe it stuck more. Here is some data. Some laps had a couple instances of the kickdown, but most laps were like this one where it only happened once at Turn 7.
For most turns you can see it is already in the correct gear before i floor it and it upshifts at redline. Perfect!
However for T7 you can see that it is in 3rd and when i floor it it kicks down to 2nd. Maybe that's because for that part of the track i'm off the throttle for a bit. I'm actually sort of trail braking/coasting through a little S part and the RPMs drop a good bit. So maybe the car thinks 3rd is good, but then kicks to action when i suddenly step on it.
It's also interesting to see the car is really only using 2nd and 3rd gear with 4th on the front straight. In my mind PDK was working like crazy, but this would be quite simple to do manually. :-D
If you are using PDK the most important thing is to make sure your beauticians license is up to date
Now, now a full beautician is not necessary but a pesky hang nail can cost you .25sec/lap or more depending on your mettle
Originally Posted by txbdan
Maybe i'm not pressing hard enough on the kick down switch or something.
I was frustrated by it too but sounds like you're already finding your way through data. In some corners I realized that if I was able to floor anywhere near apex I was not carrying enough pace and PDK was giving me a not so subtle message that I left something on the table. When hitting my target min corner speeds, in mid-high speed corners, I generally don't experience kick down because I'm building throttle and praying the car doesn't flip ends. It's become less of a problem and more of an indicator for me but there are some corners where I just can't gel with the PDK and I'll need to pull a lower gear prior to getting on throttle . YMMV
You are hitting the "kick down" when you floored the accelerator. There were two places at Summit Point that "flooring" my 09 Boxster would cause the kick down. Learned to roll into the throttle a little slower normally prevented it. Later models actually disable the kick down in Sport+. The Cobb PDK tune also eliminates kick down. With only one track weekend with my new to me 2013 Boxster S I have not had a kick down. I'm sure the extra HP and slightly different gearing have something to do with it.
In some corners I realized that if I was able to floor anywhere near apex I was not carrying enough pace and PDK was giving me a not so subtle message that I left something on the table.
When hitting my target min corner speeds, in mid-high speed corners, I generally don't experience kick down because I'm building throttle and praying the car doesn't flip ends.
YMMV
Bingo.
However, if you're building throttle as you should, it's not going to change any weight distribution so quickly that sudden swapping-of-ends will happen...
I have terabytes of top line pros driving PDK cars, and they ain't no hairdressers!
They're also, for the most part, in full auto...
__________________ -Peter Krause www.peterkrause.net www.gofasternow.com
"Combining the Art and Science of Driving Fast!"
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I'm not sure why my throttle application is a little jerky, maybe that's me rotating the car a bit, but if you blur your eyes a little its a smooth but quick ramp up to full throttle. Maybe? That lap was fairly quick. It was the 12th fastest of the event at the SCCA TTNT last weekend. And my car is bone stock on stock-width street tires.
I also find the throttle pretty touchy in Sport Plus mode.
Is there a difference in skill and difficulty between driving a PDK car versus a manual transmission? I believe yes.
Is there a difference in lap time? For club racers I believe yes, but for pro racers the data shows the advantage goes away.
I'm pretty certain I have a PDK car in my future as I have thought about moving to a Clubsport or Cup. I need to work on driving more reckless before I make that move, though.
You are hitting the "kick down" when you floored the accelerator. There were two places at Summit Point that "flooring" my 09 Boxster would cause the kick down. Learned to roll into the throttle a little slower normally prevented it. Later models actually disable the kick down in Sport+. The Cobb PDK tune also eliminates kick down. With only one track weekend with my new to me 2013 Boxster S I have not had a kick down. I'm sure the extra HP and slightly different gearing have something to do with it.
Kick down is a great indicator of your inputs in my opinion... Turn 5 at NJMP is a great example. If I get it just right I will carry enough speed that when I go back to full throttle I'm already beyond kick down and it will hold the gear I'm in. If I over slow just slightly and go back to full throttle I get kick down. It's immediate feedback for me that my VMin was off...
Trying to carry enough speed through Apex that kick down doesn't happen on exit usually tells me how effective my braking was on corner entry but I have also been known to keep pressure on the throttle under braking to keep RPM's up on the PDK, same thing on the bike, just a little helper throttle to stay in the power band and keep the platform stable. Being on both pedals at once even slightly also forces me to really balance my pedal input rather than just mash them to the floor...
Kick down is a great indicator of your inputs in my opinion... Turn 5 at NJMP is a great example. If I get it just right I will carry enough speed that when I go back to full throttle I'm already beyond kick down and it will hold the gear I'm in. If I over slow just slightly and go back to full throttle I get kick down. It's immediate feedback for me that my VMin was off...
Trying to carry enough speed through Apex that kick down doesn't happen on exit usually tells me how effective my braking was on corner entry but I have also been known to keep pressure on the throttle under braking to keep RPM's up on the PDK, same thing on the bike, just a little helper throttle to stay in the power band and keep the platform stable. Being on both pedals at once even slightly also forces me to really balance my pedal input rather than just mash them to the floor...
In this example, by "kickdown" do you mean just that if you go slow enough, PDK will downshift and if you carry enough speed, PDK will decide not to downshift? As opposed to "kickdown" in the kickdown switch sense?
What exactly does the kickdown switch do while in Sport Plus mode? Someone above said its disabled in Sport+, is that so? That'd eliminate one variable if so.
In this example, by "kickdown" do you mean just that if you go slow enough, PDK will downshift and if you carry enough speed, PDK will decide not to downshift? As opposed to "kickdown" in the kickdown switch sense?
What exactly does the kickdown switch do while in Sport Plus mode? Someone above said its disabled in Sport+, is that so? That'd eliminate one variable if so.
Spot on... If I over slow the corner the PDK will engage kick down when I return to full throttle coming out of the corner because the RPM's are so low it needs to kick down to be back in the lower power band. If I carry enough min speed and keep RPM's up when I come out of the corner and return to full throttle the gear will stay up because I'm already in the power band and likely to close to red line in the gear below...
I've found there are a lot of corners like this where you are so close to the top of the gear below if you carry enough speed it doesn't want to kick down... If I take a corner 10 times and 9/10 it doesn't kick down I did something wrong on the 1 it did
07-07-2020, 01:30 PM
