GT4 vs. GT3 on track
09-11-2015, 01:32 PM
#31
Rennlist Member
I had the good fortune to have a chance over the course of three days last week to drive a 991 Turbo S, GT4 and GT3 in open lapping on the Barber Motorsports Park track. The last of those days I got to try them in back to back sessions for around a half hour each.
Obviously all three are quite different animals. If there were beer on hand I could probably get quite carried away talking about my impressions but in short... I came away really happy with my 991TT as a DD and occasional track day toy but, boy, I was startled by how much more confidence the GT3 inspired on the track by comparison. The mind boggles at what the GT3 RS might feel like given these baselines.
If only the GT cars weren't so hard to get allocations for (...now that I've figured out exactly how much I'd really like to have one to add to the garage)
Obviously all three are quite different animals. If there were beer on hand I could probably get quite carried away talking about my impressions but in short... I came away really happy with my 991TT as a DD and occasional track day toy but, boy, I was startled by how much more confidence the GT3 inspired on the track by comparison. The mind boggles at what the GT3 RS might feel like given these baselines.
If only the GT cars weren't so hard to get allocations for (...now that I've figured out exactly how much I'd really like to have one to add to the garage)
you are not that far away from me in Vancouver WA. Were do you normally track your cars...Do you bring your 991TT to PIR? Mark
09-11-2015, 05:34 PM
#32
Three Wheelin'
But your advice is spot on, especially on braking - I have difficulty getting consistent turn entry speeds with GT3, mostly because it's just too fast and rate of speed change is so high, so what I started dong is braking a bit earlier and then half-releasing the brakes some distance before turn in to reduce the rate of speed change and make it easier to hit the right entry speeds consistently. According to the coach that advised this, it's not the way to drive all the time, but rather an exercise. It seems to be helping me with T1 and T8, but still a long way to go there.
You also could try trail braking (a lot more). I know this seems counter intuitive vs. the advice in the previous paragraph, but the two work well together. Once you become accustomed to using trail braking more, your entry speed is not a "binary" event that occurs when you stop braking at the turn-in point. You don't have to get it perfect because you can continue to control it after turn in.
In almost all corners, the lateral load builds progressively from turn in and maxes between the point of greatest rotation and the apex. In short, you have available tire grip that isn't needed for cornering that can be used for braking (and expanding your envelope for controlling how much speed to carry into the corner) for about the first 1/3 of the corner.
As I approach a corner, I like to load the front just slightly with a very quick transition to hammering the brakes for maximum braking, then I start to ease up well before the turn-in, look up through the turn and use the brakes and steering to adjust my entry speed (often almost all the way to the apex). This also helps with controlling rotation very precisely in a 911.
In a perfect world, you reduce braking progressively as you increase steering angle and transition quickly to the throttle at max rotation, then progressively increase throttle as you decrease steering angle.
09-11-2015, 09:03 PM
#33
Drifting
Spot on. This has been my sole focus for the past year - carry more speed thru the corner, particularly on entry. And it's way harder than it looks or sounds. Keeping the car flowing and composed after releasing the brakes and beginning turn-in is like learning how to become an old master at oil painting. There are so many things to manage and prevent you from doing it smoothly. My nemesis is muscle memory and self-preservation. I hit the brakes and turn in at Thunderhill mainly on muscle memory (I'm way better at adjusting my reference points at other tracks where I'm not as familiar). And self-preservation tends to make you hit the brakes harder or turn the wheel more aggressively than we should.
I do enjoy the challenge though. This is a life-long pursuit!
I do enjoy the challenge though. This is a life-long pursuit!
One thing about both brakes and throttle earlier. I'm using Aim Solo on OBD port, and it has about 0.1-0.2sec delay for pedal overlay graphics, which is about 1-2 car lengths, or about 20-30 feet you are suggesting. It's pretty obvious if you compare engine sound to the throttle position indicator. So it does look like I'm way too late on brakes and on throttle, but that's not always the case or not to the extent it may seem. I asked around how to fix it, and the consensus is that switching to canbus is going to help.
But your advice is spot on, especially on braking - I have difficulty getting consistent turn entry speeds with GT3, mostly because it's just too fast and rate of speed change is so high, so what I started dong is braking a bit earlier and then half-releasing the brakes some distance before turn in to reduce the rate of speed change and make it easier to hit the right entry speeds consistently. According to the coach that advised this, it's not the way to drive all the time, but rather an exercise. It seems to be helping me with T1 and T8, but still a long way to go there.
And you are right about the entry speed, particularly in fast corners - I could carry in more, and that's what GT4 in the video does.
Regarding 1.55 - definitely possible. I've done mid 1:55.x more than once with bypass, but could only do 1:57:9x
with the cyclone, and I'm leaving a lot on the table even just those things I know of (one thing is knowing, another is ability to execute perfectly)
But your advice is spot on, especially on braking - I have difficulty getting consistent turn entry speeds with GT3, mostly because it's just too fast and rate of speed change is so high, so what I started dong is braking a bit earlier and then half-releasing the brakes some distance before turn in to reduce the rate of speed change and make it easier to hit the right entry speeds consistently. According to the coach that advised this, it's not the way to drive all the time, but rather an exercise. It seems to be helping me with T1 and T8, but still a long way to go there.
And you are right about the entry speed, particularly in fast corners - I could carry in more, and that's what GT4 in the video does.
Regarding 1.55 - definitely possible. I've done mid 1:55.x more than once with bypass, but could only do 1:57:9x
with the cyclone, and I'm leaving a lot on the table even just those things I know of (one thing is knowing, another is ability to execute perfectly)
It's actually not a bad strategy to use all the time. Data analysis of Micheal Shumi vs. contemporaries showed he hit the brakes earlier, less hard and carried more speed into the corner. He wasn't fighting the typical mistake we all make where we are trying to brake as late as possible and time the turn-in speed perfectly while fighting the car.
You also could try trail braking (a lot more). I know this seems counter intuitive vs. the advice in the previous paragraph, but the two work well together. Once you become accustomed to using trail braking more, your entry speed is not a "binary" event that occurs when you stop braking at the turn-in point. You don't have to get it perfect because you can continue to control it after turn in.
In almost all corners, the lateral load builds progressively from turn in and maxes between the point of greatest rotation and the apex. In short, you have available tire grip that isn't needed for cornering that can be used for braking (and expanding your envelope for controlling how much speed to carry into the corner) for about the first 1/3 of the corner.
As I approach a corner, I like to load the front just slightly with a very quick transition to hammering the brakes for maximum braking, then I start to ease up well before the turn-in, look up through the turn and use the brakes and steering to adjust my entry speed (often almost all the way to the apex). This also helps with controlling rotation very precisely in a 911.
In a perfect world, you reduce braking progressively as you increase steering angle and transition quickly to the throttle at max rotation, then progressively increase throttle as you decrease steering angle.
You also could try trail braking (a lot more). I know this seems counter intuitive vs. the advice in the previous paragraph, but the two work well together. Once you become accustomed to using trail braking more, your entry speed is not a "binary" event that occurs when you stop braking at the turn-in point. You don't have to get it perfect because you can continue to control it after turn in.
In almost all corners, the lateral load builds progressively from turn in and maxes between the point of greatest rotation and the apex. In short, you have available tire grip that isn't needed for cornering that can be used for braking (and expanding your envelope for controlling how much speed to carry into the corner) for about the first 1/3 of the corner.
As I approach a corner, I like to load the front just slightly with a very quick transition to hammering the brakes for maximum braking, then I start to ease up well before the turn-in, look up through the turn and use the brakes and steering to adjust my entry speed (often almost all the way to the apex). This also helps with controlling rotation very precisely in a 911.
In a perfect world, you reduce braking progressively as you increase steering angle and transition quickly to the throttle at max rotation, then progressively increase throttle as you decrease steering angle.
I make mistake's myself.
Example: turn 10- I'm afraid of it. I know i can go 7-10 mph faster into but I have a mental barrier due some incident I have on that corner before and in the video below towards the end you will see an incident as well. And honestly, that is the hardest turn for me. Also caring a passenger this session and I don't like going over 8/10s with a passenger. Especially with a lot of incidents that have happened over the last 2 years with passengers on track.
That along with turn 14, I know i'm braking way to late but turn 14 is a throw away. If i had 265 or 275 width up front vs 245 like i have now, that will help me tremendously under braking on the front load. What I really need is control the brake bias and send some brake bias to the rear, but this is a street car and I just go puddle around to the track, and my alignments spec are for street driving.
anyways Max, maybe i'll see you on track later this year! Take care.
https://vimeo.com/135873205
09-11-2015, 10:43 PM
#34
Rennlist Member
Example: turn 10- I'm afraid of it. I know i can go 7-10 mph faster into but I have a mental barrier due some incident I have on that corner before and in the video below towards the end you will see an incident as well. And honestly, that is the hardest turn for me. Also caring a passenger this session and I don't like going over 8/10s with a passenger. Especially with a lot of incidents that have happened over the last 2 years with passengers on track.
That along with turn 14, I know i'm braking way to late but turn 14 is a throw away. If i had 265 or 275 width up front vs 245 like i have now, that will help me tremendously under braking on the front load. What I really need is control the brake bias and send some brake bias to the rear, but this is a street car and I just go puddle around to the track, and my alignments spec are for street driving.
anyways Max, maybe i'll see you on track later this year! Take care.
https://vimeo.com/135873205
That along with turn 14, I know i'm braking way to late but turn 14 is a throw away. If i had 265 or 275 width up front vs 245 like i have now, that will help me tremendously under braking on the front load. What I really need is control the brake bias and send some brake bias to the rear, but this is a street car and I just go puddle around to the track, and my alignments spec are for street driving.
anyways Max, maybe i'll see you on track later this year! Take care.
https://vimeo.com/135873205
What was up with the black Mustang at the end of the video. Very reckless & unprofessional. Mark
09-11-2015, 11:58 PM
#35
Rennlist Member
Nice Video, thanks for sharing. Indeed when you were braking early, you appear to be carrying more speed into the turn, and your line was much better & more composed. Enjoyed the video! Thank you. What was up with the black Mustang at the end of the video. Very reckless & unprofessional. Mark
Looking forward to catching up in a couple weeks!
09-12-2015, 12:00 AM
#36
Rennlist Member
Of course I realize I didn't say much about the GT4. The manual gearbox was terrific to operate and I didn't really sense any issue with ratios around the Barber track (caveat: I'm still pretty new to this kind of driving). Comparing the GT3 and GT4 aside from the obvious power differential the main thing I felt was that pointing the car where I wanted to go was a bit softer in the GT4 compared to the GT3 that felt more precise to me...maybe a bit more understeer that would be ideal?? I mentioned this to one of the pro instructors and he said that they concluded that the GT4 could use a bit more front tire but they all really like it aside from that one little critique. As a confirmed manual transmission devotee I expected to like the GT4 more just for that...not so really...didn't miss it in the GT3 which just felt more thrilling overall.
Heh -- I probably drive past you quite often heading for Hillsboro I have not been down to PIR; so far only run with the PNWR folks up at the Ridge or Pacific Raceways this year and last. Perhaps I should get brave and come down to PIR next season as well for a taste of a big name track Actually my daughter just started at UP so perhaps I have even more excuse to trek down that way for the next couple of years. Could I talk you into sending a PM to clue me in on how to find groups that run at PIR??
I'm actually enjoying this thread a lot...looking at data from runs last week it's clear that I have the same "opportunity" to that being discussed here: leaving grip on the table not carrying as much speed into turns where a hard-early-trail-towards-apex braking approach would yield better balance and higher entry speed. Comparing to instructor reference laps I'm about 4 seconds off the pace and the three big places I lose time is in turn 1-to-2, 7-to-8 and 11-to-12 which have faster entry turns followed by a slower one...I overbrake and then have a lower speed overall through those turns. Something to work on for sure!
I realize I didn't say much about the GT4. The manual gearbox was terrific to operate and I didn't really sense any issue with ratios around the Barber track (caveat: I'm still pretty new to this kind of driving). Comparing the GT3 and GT4 aside from the obvious power differential the main thing I felt was that pointing the car where I wanted to go was a bit softer in the GT4 compared to the GT3 that felt more precise to me...maybe a bit more understeer that would be ideal?? I mentioned this to one of the pro instructors and he said that they concluded that the GT4 could use a bit more front tire but they all really like it aside from that one little critique. As a confirmed manual transmission devotee I expected to like the GT4 more just for that...not so really...didn't miss it in the GT3 which just felt more thrilling overall.
you are not that far away from me in Vancouver WA. Were do you normally track your cars...Do you bring your 991TT to PIR? Mark
I have not been down to PIR; so far only run with the PNWR folks up at the Ridge or Pacific Raceways this year and last. Perhaps I should get brave and come down to PIR next season as well for a taste of a big name track Actually my daughter just started at UP so perhaps I have even more excuse to trek down that way for the next couple of years. Could I talk you into sending a PM to clue me in on how to find groups that run at PIR??I'm actually enjoying this thread a lot...looking at data from runs last week it's clear that I have the same "opportunity" to that being discussed here: leaving grip on the table not carrying as much speed into turns where a hard-early-trail-towards-apex braking approach would yield better balance and higher entry speed. Comparing to instructor reference laps I'm about 4 seconds off the pace and the three big places I lose time is in turn 1-to-2, 7-to-8 and 11-to-12 which have faster entry turns followed by a slower one...I overbrake and then have a lower speed overall through those turns. Something to work on for sure!
09-12-2015, 12:50 AM
#37
Race Car
Max, great video - GT3 sounds fantastic. What App/software are you using that shows the dials and RPM like that? Is it compatible with other cars too?
09-12-2015, 06:18 PM
#38
Rennlist Member
Thread Starter
Join Date: Jan 2013
Location: West Vancouver and San Francisco
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It's AIM Solo with Smartycam HD 2.0. So not really software but hardware solution. External microphone wired into the engine bay. I would not necessarily recommend Smartycam HD 2 - image quality is still not as good as GoPro and there is noticeable lag for overlay graphics, particularly when connected to OBD.
09-12-2015, 09:38 PM
#39
Rennlist Member
09-12-2015, 09:52 PM
#40
Rennlist Member
Of course I realize I didn't say much about the GT4. The manual gearbox was terrific to operate and I didn't really sense any issue with ratios around the Barber track (caveat: I'm still pretty new to this kind of driving). Comparing the GT3 and GT4 aside from the obvious power differential the main thing I felt was that pointing the car where I wanted to go was a bit softer in the GT4 compared to the GT3 that felt more precise to me...maybe a bit more understeer that would be ideal?? I mentioned this to one of the pro instructors and he said that they concluded that the GT4 could use a bit more front tire but they all really like it aside from that one little critique. As a confirmed manual transmission devotee I expected to like the GT4 more just for that...not so really...didn't miss it in the GT3 which just felt more thrilling overall.
Heh -- I probably drive past you quite often heading for Hillsboro I have not been down to PIR; so far only run with the PNWR folks up at the Ridge or Pacific Raceways this year and last. Perhaps I should get brave and come down to PIR next season as well for a taste of a big name track Actually my daughter just started at UP so perhaps I have even more excuse to trek down that way for the next couple of years. Could I talk you into sending a PM to clue me in on how to find groups that run at PIR??
I'm actually enjoying this thread a lot...looking at data from runs last week it's clear that I have the same "opportunity" to that being discussed here: leaving grip on the table not carrying as much speed into turns where a hard-early-trail-towards-apex braking approach would yield better balance and higher entry speed. Comparing to instructor reference laps I'm about 4 seconds off the pace and the three big places I lose time is in turn 1-to-2, 7-to-8 and 11-to-12 which have faster entry turns followed by a slower one...I overbrake and then have a lower speed overall through those turns. Something to work on for sure!
I realize I didn't say much about the GT4. The manual gearbox was terrific to operate and I didn't really sense any issue with ratios around the Barber track (caveat: I'm still pretty new to this kind of driving). Comparing the GT3 and GT4 aside from the obvious power differential the main thing I felt was that pointing the car where I wanted to go was a bit softer in the GT4 compared to the GT3 that felt more precise to me...maybe a bit more understeer that would be ideal?? I mentioned this to one of the pro instructors and he said that they concluded that the GT4 could use a bit more front tire but they all really like it aside from that one little critique. As a confirmed manual transmission devotee I expected to like the GT4 more just for that...not so really...didn't miss it in the GT3 which just felt more thrilling overall.Heh -- I probably drive past you quite often heading for Hillsboro
I have not been down to PIR; so far only run with the PNWR folks up at the Ridge or Pacific Raceways this year and last. Perhaps I should get brave and come down to PIR next season as well for a taste of a big name track Actually my daughter just started at UP so perhaps I have even more excuse to trek down that way for the next couple of years. Could I talk you into sending a PM to clue me in on how to find groups that run at PIR??I'm actually enjoying this thread a lot...looking at data from runs last week it's clear that I have the same "opportunity" to that being discussed here: leaving grip on the table not carrying as much speed into turns where a hard-early-trail-towards-apex braking approach would yield better balance and higher entry speed. Comparing to instructor reference laps I'm about 4 seconds off the pace and the three big places I lose time is in turn 1-to-2, 7-to-8 and 11-to-12 which have faster entry turns followed by a slower one...I overbrake and then have a lower speed overall through those turns. Something to work on for sure!
Thank you so much for the additional review. I guess in my case since I am going to own both cars (GT3 & GT4), I will have the best of both worlds, and I a, planning to do a detailed review shortly after I take position of my GT4.
You have picked a great school for your daughter. I got my engineering degree from UP back in 1986 and I am still involved with the school and get invited to lecture at the school from time to time. You are more than welcome to contact me if you need assistance.
As for PIR, I am active with few clubs including ORPCA, which has many track & auto-crosses activities at PIR most of the year. I will send you a PM with my contact information and please feel free to contact me at anytime. I will be more than happy to give you more information about track activities. Also hoping to meet you in person soon. Mark
