Orthojoe's GT4 track thread and ramblings
01-05-2017, 12:02 AM
#1006
Firstly, thanks so much for your immense contribution.
I know I am going back to a page 3 post, but my question is regarding the data and your braking style.
And this may be hard to answer because braking depends on the type of corner etc. I also have never driven any West Coast tracks, but do you stab then completely come off the brakes, or do you crush, then slowly release and trail off?
Because the graphs are compressed to fit onto one page, I may be reading the brake pressure data wrong. But it looks like you are full on, or full off... i don't think i see any trailing (which might not even be needed from the vids i have seen).
But again, i think i am reading the data wrong... still learning here. Thanks again, and sorry if the misread is on my end.
I know I am going back to a page 3 post, but my question is regarding the data and your braking style.
And this may be hard to answer because braking depends on the type of corner etc. I also have never driven any West Coast tracks, but do you stab then completely come off the brakes, or do you crush, then slowly release and trail off?
Because the graphs are compressed to fit onto one page, I may be reading the brake pressure data wrong. But it looks like you are full on, or full off... i don't think i see any trailing (which might not even be needed from the vids i have seen).
But again, i think i am reading the data wrong... still learning here. Thanks again, and sorry if the misread is on my end.
Now for my favorite part: Data. It never lies. It tells you a lot. This data is from thunderhill running the cyclone config. GT4 on cup2 tires. GT3 on cup2 tires. Spyder on NT01
This is a graph comparing my 2:01.2 GT4 lap against a 1:58.5 lap in the GT3. You can see that the peak velocity down the main straight hits 132.7 mph in the GT4 vs 140.1 mph in the GT3. GT3 in red. GT4 in blue. Speed in the first row, throttle position 2nd row, Brake pressure 3rd row, and time differential 4th row.
Next is a graph comparing a 2:01.2 in the GT4 vs a 2:04.3 in the boxster spyder running NT01 tires. GT4 max speed is 132.7mph vs 128.6mph in the spyder. GT4 in blue. 2011 Spyder in red.
This graphs combines the spyder, GT4, and 991 GT3 all on one
GT4 blue, GT3 red, spyder green
GT4 only
DISCUSS!!
This is a graph comparing my 2:01.2 GT4 lap against a 1:58.5 lap in the GT3. You can see that the peak velocity down the main straight hits 132.7 mph in the GT4 vs 140.1 mph in the GT3. GT3 in red. GT4 in blue. Speed in the first row, throttle position 2nd row, Brake pressure 3rd row, and time differential 4th row.
Next is a graph comparing a 2:01.2 in the GT4 vs a 2:04.3 in the boxster spyder running NT01 tires. GT4 max speed is 132.7mph vs 128.6mph in the spyder. GT4 in blue. 2011 Spyder in red.
This graphs combines the spyder, GT4, and 991 GT3 all on one
GT4 blue, GT3 red, spyder green
GT4 only
DISCUSS!!
01-05-2017, 08:45 AM
#1007
Burning Brakes
Joe's brake pressure traces look pretty good to me! His rise and attack time on initial brake application are mostly very good. It is difficult to look at these graphs and judge how well he is trail braking without also looking at his lateral and longitudinal G's, or better yet, his combined G's. That is what is needed to see how well he is mating braking force to cornering force.
01-05-2017, 10:17 AM
#1008
Nordschleife Master
Thread Starter
Originally Posted by GTS_Ninja
Firstly, thanks so much for your immense contribution.
I know I am going back to a page 3 post, but my question is regarding the data and your braking style.
And this may be hard to answer because braking depends on the type of corner etc. I also have never driven any West Coast tracks, but do you stab then completely come off the brakes, or do you crush, then slowly release and trail off?
Because the graphs are compressed to fit onto one page, I may be reading the brake pressure data wrong. But it looks like you are full on, or full off... i don't think i see any trailing (which might not even be needed from the vids i have seen).
But again, i think i am reading the data wrong... still learning here. Thanks again, and sorry if the misread is on my end.
I know I am going back to a page 3 post, but my question is regarding the data and your braking style.
And this may be hard to answer because braking depends on the type of corner etc. I also have never driven any West Coast tracks, but do you stab then completely come off the brakes, or do you crush, then slowly release and trail off?
Because the graphs are compressed to fit onto one page, I may be reading the brake pressure data wrong. But it looks like you are full on, or full off... i don't think i see any trailing (which might not even be needed from the vids i have seen).
But again, i think i am reading the data wrong... still learning here. Thanks again, and sorry if the misread is on my end.
The goal is to 'crush and then slowly release and trail off'. This is something I'm still working on. It's not applicable to every corner, but certain corners like T14 really benefit from it. Getting the timing down just right so you don't brake too early or too late so you can take advantage of this is the hardest part.
01-05-2017, 05:01 PM
#1009
G-sum channel ey? I see someone here knows there stuff... niiice!
Joe's brake pressure traces look pretty good to me! His rise and attack time on initial brake application are mostly very good. It is difficult to look at these graphs and judge how well he is trail braking without also looking at his lateral and longitudinal G's, or better yet, his combined G's. That is what is needed to see how well he is mating braking force to cornering force.
01-05-2017, 08:13 PM
#1010
G-Sum is a graphical view of the friction circle. I recently started to add G-Sum analysis in my data review. If you have an AiM system, you can use the math channel to write the equation and create a graph. Here's an example from a lap at Watkins Glen.
01-06-2017, 01:04 AM
#1012
Nordschleife Master
Thread Starter
I'm not familiar with G-sum. Can you tell me how to understand this? Thanks!
01-06-2017, 07:27 AM
#1013
Burning Brakes
Combined G's, or G-Sum as it is often known, is the total combined force of lateral and longitudinal G forces. Most track-oriented data loggers include accelerometers that measure these forces. After measuring time and distance (e.g., speed), G forces are the next most important measure of driver performance.
GTS-Ninja above specifically asked about orthojoe's braking style and questioned whether or not he was trail braking. G-Sum is the easiest way to measure effective trail braking.
Here's the theory behind G-Sum: For a given tire, there will be a maximum amount of grip it can generate in any direction. In order to go as fast as possible around a race track you want to (with few exceptions) always be using ALL of the tire grip available to you. If you don't then you are simply leaving time on the table.
Longitudinal G forces are a measure of braking force and lateral G forces are a measure of cornering force. The goal for fast lap times is to compress the braking zone (e.g., spend as little time as possible on the brakes), generate maximum cornering forces, and stay on the gas as much as possible. Without getting into too much detail about what a good brake profile looks like let's just say you want to get off the gas and up to maximum brake pressure for that corner as quickly as possible. And then, as you begin to trail off the brake pressure and your longitudinal G forces subside, you want to begin turning into the corner and replace those dropping longitudinal G forces with lateral G forces.
For the purposes of this discussion let's say the tires on your car on a given day can generate 1.5 G's. That will be their limit in any direction. When looking at your G-Sum in a given corner you want to see your G forces rise quickly to 1.5 G's as you begin to slow the car, and then stay at 1.5 G's as you go through the corner. The G-Sum should begin to drop as you get back to power and exit the corner.
Nearly all drivers execute this poorly. Most drivers don't reach maximum brake force quickly enough. They often reach maximum brake force too early and then they back off and coast into the corner. Good trail braking, and fast lap times, will come from keeping the dip as low as possible in G-Sum.
This, by the way, is probably the lowest hanging fruit on the path to faster lap times. Most drivers brake too hard and too soon for a given corner. Time is then lost as they coast into the corner, or worse, have to get back on the gas before they turn into the corner. The easiest way to measure this is through data analysis. It's difficult to measure this skill without it. And most drivers think they're executing this skill MUCh better than they really are.
GTS-Ninja above specifically asked about orthojoe's braking style and questioned whether or not he was trail braking. G-Sum is the easiest way to measure effective trail braking.
Here's the theory behind G-Sum: For a given tire, there will be a maximum amount of grip it can generate in any direction. In order to go as fast as possible around a race track you want to (with few exceptions) always be using ALL of the tire grip available to you. If you don't then you are simply leaving time on the table.
Longitudinal G forces are a measure of braking force and lateral G forces are a measure of cornering force. The goal for fast lap times is to compress the braking zone (e.g., spend as little time as possible on the brakes), generate maximum cornering forces, and stay on the gas as much as possible. Without getting into too much detail about what a good brake profile looks like let's just say you want to get off the gas and up to maximum brake pressure for that corner as quickly as possible. And then, as you begin to trail off the brake pressure and your longitudinal G forces subside, you want to begin turning into the corner and replace those dropping longitudinal G forces with lateral G forces.
For the purposes of this discussion let's say the tires on your car on a given day can generate 1.5 G's. That will be their limit in any direction. When looking at your G-Sum in a given corner you want to see your G forces rise quickly to 1.5 G's as you begin to slow the car, and then stay at 1.5 G's as you go through the corner. The G-Sum should begin to drop as you get back to power and exit the corner.
Nearly all drivers execute this poorly. Most drivers don't reach maximum brake force quickly enough. They often reach maximum brake force too early and then they back off and coast into the corner. Good trail braking, and fast lap times, will come from keeping the dip as low as possible in G-Sum.
This, by the way, is probably the lowest hanging fruit on the path to faster lap times. Most drivers brake too hard and too soon for a given corner. Time is then lost as they coast into the corner, or worse, have to get back on the gas before they turn into the corner. The easiest way to measure this is through data analysis. It's difficult to measure this skill without it. And most drivers think they're executing this skill MUCh better than they really are.
01-06-2017, 09:29 AM
#1014
Beantown Kman, That's an excellent explanation. Joe, There was a discussion on setting up this channel over on the Data Acquisition section of the Racing and DE forum. The formula has to be written using the exact nomenclature sent by your logger. The "Canned" formula has to be modified as the some of the data coming from the Solo DL has different names. I'll try to send a screen shot later.
01-06-2017, 10:46 AM
#1015
Here's a screen shot of my math channel setup for GSum. You have to use the "Identifiers" coming from your logger in the formula. Do not use the "General" tab for this setup. I understand that once this is setup, it will automatically show on the "General" tab on future tests. My season is over until April, just finished plowing snow.
01-06-2017, 11:03 AM
#1016
Nordschleife Master
Thread Starter
Thanks, guys!!
Beantown, great explanation. I woke up this morning thinking about it and surmised exactly as you explained. Ha! Makes total sense and it is indeed a valuable tool now that I understand it.
Bill, thank you for bringing this up! Yes, I'm familiar with how to modify the math channels to account for how the logger names the channels. I was forced to figure this out a while ago because I could never get the solo to calculate gear automatically so I always had to do it post hoc for my videos by using the math channel. Rs2 is not for the faint of heart, but very powerful if you can figure it out!
I guess I should hang out in the DE/racing subforum more!
Thanks again!
Beantown, great explanation. I woke up this morning thinking about it and surmised exactly as you explained. Ha! Makes total sense and it is indeed a valuable tool now that I understand it.
Bill, thank you for bringing this up! Yes, I'm familiar with how to modify the math channels to account for how the logger names the channels. I was forced to figure this out a while ago because I could never get the solo to calculate gear automatically so I always had to do it post hoc for my videos by using the math channel. Rs2 is not for the faint of heart, but very powerful if you can figure it out!
I guess I should hang out in the DE/racing subforum more!
Thanks again!
01-10-2017, 02:07 PM
#1018
Great thread!!
Apologies for a slightly off topic question. I am going to load up the GT4 on my trailer and spend the month of July visiting tracks around the country. Seems like a large number of people on this thread are on the west coast. Is there a private HPDE group that books the good tracks? Chin Motorsports does a great job in the Midwest and East coast, but I am having trouble finding something similar in the west. This is the best thread an kudos to Joe for the effort. I found it when I first bought my GT4 and it saved me a lot of the experimentation I have gone through with other track cars.
Apologies for a slightly off topic question. I am going to load up the GT4 on my trailer and spend the month of July visiting tracks around the country. Seems like a large number of people on this thread are on the west coast. Is there a private HPDE group that books the good tracks? Chin Motorsports does a great job in the Midwest and East coast, but I am having trouble finding something similar in the west. This is the best thread an kudos to Joe for the effort. I found it when I first bought my GT4 and it saved me a lot of the experimentation I have gone through with other track cars.
01-10-2017, 04:16 PM
#1019
Nordschleife Master
Thread Starter
Originally Posted by gene.will
Great thread!!
Apologies for a slightly off topic question. I am going to load up the GT4 on my trailer and spend the month of July visiting tracks around the country. Seems like a large number of people on this thread are on the west coast. Is there a private HPDE group that books the good tracks? Chin Motorsports does a great job in the Midwest and East coast, but I am having trouble finding something similar in the west. This is the best thread an kudos to Joe for the effort. I found it when I first bought my GT4 and it saved me a lot of the experimentation I have gone through with other track cars.
Apologies for a slightly off topic question. I am going to load up the GT4 on my trailer and spend the month of July visiting tracks around the country. Seems like a large number of people on this thread are on the west coast. Is there a private HPDE group that books the good tracks? Chin Motorsports does a great job in the Midwest and East coast, but I am having trouble finding something similar in the west. This is the best thread an kudos to Joe for the effort. I found it when I first bought my GT4 and it saved me a lot of the experimentation I have gone through with other track cars.
Up here in NorCal, the hpde groups I run with are hooked on driving, speedSF, and trackmasters. Once in a while mooty and I will run private track days too.
01-10-2017, 05:27 PM
#1020
Combined G's, or G-Sum as it is often known, is the total combined force of lateral and longitudinal G forces. Most track-oriented data loggers include accelerometers that measure these forces. After measuring time and distance (e.g., speed), G forces are the next most important measure of driver performance.
GTS-Ninja above specifically asked about orthojoe's braking style and questioned whether or not he was trail braking. G-Sum is the easiest way to measure effective trail braking.
Here's the theory behind G-Sum: For a given tire, there will be a maximum amount of grip it can generate in any direction. In order to go as fast as possible around a race track you want to (with few exceptions) always be using ALL of the tire grip available to you. If you don't then you are simply leaving time on the table.
Longitudinal G forces are a measure of braking force and lateral G forces are a measure of cornering force. The goal for fast lap times is to compress the braking zone (e.g., spend as little time as possible on the brakes), generate maximum cornering forces, and stay on the gas as much as possible. Without getting into too much detail about what a good brake profile looks like let's just say you want to get off the gas and up to maximum brake pressure for that corner as quickly as possible. And then, as you begin to trail off the brake pressure and your longitudinal G forces subside, you want to begin turning into the corner and replace those dropping longitudinal G forces with lateral G forces.
For the purposes of this discussion let's say the tires on your car on a given day can generate 1.5 G's. That will be their limit in any direction. When looking at your G-Sum in a given corner you want to see your G forces rise quickly to 1.5 G's as you begin to slow the car, and then stay at 1.5 G's as you go through the corner. The G-Sum should begin to drop as you get back to power and exit the corner.
Nearly all drivers execute this poorly. Most drivers don't reach maximum brake force quickly enough. They often reach maximum brake force too early and then they back off and coast into the corner. Good trail braking, and fast lap times, will come from keeping the dip as low as possible in G-Sum.
This, by the way, is probably the lowest hanging fruit on the path to faster lap times. Most drivers brake too hard and too soon for a given corner. Time is then lost as they coast into the corner, or worse, have to get back on the gas before they turn into the corner. The easiest way to measure this is through data analysis. It's difficult to measure this skill without it. And most drivers think they're executing this skill MUCh better than they really are.
GTS-Ninja above specifically asked about orthojoe's braking style and questioned whether or not he was trail braking. G-Sum is the easiest way to measure effective trail braking.
Here's the theory behind G-Sum: For a given tire, there will be a maximum amount of grip it can generate in any direction. In order to go as fast as possible around a race track you want to (with few exceptions) always be using ALL of the tire grip available to you. If you don't then you are simply leaving time on the table.
Longitudinal G forces are a measure of braking force and lateral G forces are a measure of cornering force. The goal for fast lap times is to compress the braking zone (e.g., spend as little time as possible on the brakes), generate maximum cornering forces, and stay on the gas as much as possible. Without getting into too much detail about what a good brake profile looks like let's just say you want to get off the gas and up to maximum brake pressure for that corner as quickly as possible. And then, as you begin to trail off the brake pressure and your longitudinal G forces subside, you want to begin turning into the corner and replace those dropping longitudinal G forces with lateral G forces.
For the purposes of this discussion let's say the tires on your car on a given day can generate 1.5 G's. That will be their limit in any direction. When looking at your G-Sum in a given corner you want to see your G forces rise quickly to 1.5 G's as you begin to slow the car, and then stay at 1.5 G's as you go through the corner. The G-Sum should begin to drop as you get back to power and exit the corner.
Nearly all drivers execute this poorly. Most drivers don't reach maximum brake force quickly enough. They often reach maximum brake force too early and then they back off and coast into the corner. Good trail braking, and fast lap times, will come from keeping the dip as low as possible in G-Sum.
This, by the way, is probably the lowest hanging fruit on the path to faster lap times. Most drivers brake too hard and too soon for a given corner. Time is then lost as they coast into the corner, or worse, have to get back on the gas before they turn into the corner. The easiest way to measure this is through data analysis. It's difficult to measure this skill without it. And most drivers think they're executing this skill MUCh better than they really are.
Unless you are getting a pro-coach who does video, data, and comparative analysis, you are really just reinforcing poor driving technique. I paid top dollar to have a top coach in the right seat, and since then i feel like i am going just as fast, if not faster, while exerting less effort, and not beating up on the consumables.
Here is a huge tip...
If you are already at a high skill level or respectable lap time, and you hit that ceiling... the secret is in the braking.