Tuning with a Pyrometer
12-26-2008, 04:24 PM
#1
Race Car
Thread Starter
Tuning with a Pyrometer
My lovely wife was kind enough to get me an AccuTech pyrometer for Christmas so now I"m looking for Tutorials, articles or literature of any sort on tuning with a Pyrometer.
My hunch was I actually had a bit too much camber last yaer but I'm changing tires this year so it's going to be a whole new ballgame.
I understand the basics in that you need to evaluate what the last few turns were before the pits, need to take a reading in the hot pits right after a flying lap, and that it's generally accepted that the inside should be slightly warmer than the middle and outside of the tire.
I'm assuming this is just breaking the surface on what I really need to know now that I've got an accurate means of gathering data. Looking for some further insight on how to properly tune with the pyrometer.
Andy
My hunch was I actually had a bit too much camber last yaer but I'm changing tires this year so it's going to be a whole new ballgame.
I understand the basics in that you need to evaluate what the last few turns were before the pits, need to take a reading in the hot pits right after a flying lap, and that it's generally accepted that the inside should be slightly warmer than the middle and outside of the tire.
I'm assuming this is just breaking the surface on what I really need to know now that I've got an accurate means of gathering data. Looking for some further insight on how to properly tune with the pyrometer.
Andy
12-26-2008, 04:44 PM
#2
Right after a flying lap is the most accurate data. Temperatures taken in the paddock are still useful.
I'm keeping a log book where I note where I'm driving, setup changes, alignment values, tire types, ambient conditions handling observations.
Hotter temp in the middle then on either edge says you should lower pressure. One edge a lot hotter (10 degrees?) usually needs to be fixed with alignment. Insufficient camber or understeer can heat up outer edges in front. Wrong toe or too much negative camber can kill inner edges. Consistent corner exit throttle oversteer can kill outer edges of rear tires.
I'm keeping a log book where I note where I'm driving, setup changes, alignment values, tire types, ambient conditions handling observations.
Hotter temp in the middle then on either edge says you should lower pressure. One edge a lot hotter (10 degrees?) usually needs to be fixed with alignment. Insufficient camber or understeer can heat up outer edges in front. Wrong toe or too much negative camber can kill inner edges. Consistent corner exit throttle oversteer can kill outer edges of rear tires.
12-26-2008, 04:51 PM
#3
Nordschleife Master
Sounds like you pretty much got it... there's not too much you can do with tire temps outside of set camber and tire pressure.
The reality is that mid-corner you heat up the outside of the tire and straightline braking / accel heats up the inside... the temperatures you'll be looking at with your pyrometer will be an average of all of these.
I've seen real time data with 3 IR temp sensors across the tire and the heat that the outside of the tire gains at mid-corner goes away pretty quickly and the same can be said on the inside of the tire. By the time you pull into the pits and check your temps...you'll be looking at averages. Which is good, since really the goal at this level is even tire wear IMO. Even temps = even tire wear...
Tire temps can also tell you if you have are understeering a lot. If you come into the pits and the inside of the front tires is very hot (while it's usually not)...that may mean that the car was understeering. Since when the car is understeering, people tend to crank in more steering ... which gives you more negative camber due to caster. Of course...the driver should know this just from driving the car.
The reality is that mid-corner you heat up the outside of the tire and straightline braking / accel heats up the inside... the temperatures you'll be looking at with your pyrometer will be an average of all of these.
I've seen real time data with 3 IR temp sensors across the tire and the heat that the outside of the tire gains at mid-corner goes away pretty quickly and the same can be said on the inside of the tire. By the time you pull into the pits and check your temps...you'll be looking at averages. Which is good, since really the goal at this level is even tire wear IMO. Even temps = even tire wear...
Tire temps can also tell you if you have are understeering a lot. If you come into the pits and the inside of the front tires is very hot (while it's usually not)...that may mean that the car was understeering. Since when the car is understeering, people tend to crank in more steering ... which gives you more negative camber due to caster. Of course...the driver should know this just from driving the car.
12-26-2008, 05:14 PM
#4
Drifting
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+1 a pyro is used to set camber and pressure. Your goal is even temps across the tire's surface. Keep a log and factor in ambient temps and track temps (put the probe on the floor in the pit.) Our July race had track temps in the 140's which is very important considering hot temps for r comps is around 200F but check with the tire manufacturer for the ideal temps and pressure as a guideline assuming all other variables are held constant.
Keep in mind that temperature pressure and volume are all related mathematically (remember PV=nRT) so in order to "set" one variable you must keep all others constant. So think of it as temperature at a certain pressure. What i'm trying to say poorly is that your tires need to be hot right off the track with no cool down laps, pull into the pits and have someone in the hot pits with your pyro and pressure gage read inside middle and outer THEN go and do a cool down lap and come in. Otherwise you are not getting accurate readings. Temperature and pressure irrc goes down exponentially with time. (don't make me look up the equation)
I personally have my crew waiting in the hot pits with the gear when i come off my practice laps to ensure the correct settings for qualifying
Keep in mind that temperature pressure and volume are all related mathematically (remember PV=nRT) so in order to "set" one variable you must keep all others constant. So think of it as temperature at a certain pressure. What i'm trying to say poorly is that your tires need to be hot right off the track with no cool down laps, pull into the pits and have someone in the hot pits with your pyro and pressure gage read inside middle and outer THEN go and do a cool down lap and come in. Otherwise you are not getting accurate readings. Temperature and pressure irrc goes down exponentially with time. (don't make me look up the equation)
I personally have my crew waiting in the hot pits with the gear when i come off my practice laps to ensure the correct settings for qualifying
12-26-2008, 07:22 PM
#6
Rennlist Member
My lovely wife was kind enough to get me an AccuTech pyrometer for Christmas so now I"m looking for Tutorials, articles or literature of any sort on tuning with a Pyrometer.
My hunch was I actually had a bit too much camber last yaer but I'm changing tires this year so it's going to be a whole new ballgame.
I understand the basics in that you need to evaluate what the last few turns were before the pits, need to take a reading in the hot pits right after a flying lap, and that it's generally accepted that the inside should be slightly warmer than the middle and outside of the tire.
I'm assuming this is just breaking the surface on what I really need to know now that I've got an accurate means of gathering data. Looking for some further insight on how to properly tune with the pyrometer.
Andy
My hunch was I actually had a bit too much camber last yaer but I'm changing tires this year so it's going to be a whole new ballgame.
I understand the basics in that you need to evaluate what the last few turns were before the pits, need to take a reading in the hot pits right after a flying lap, and that it's generally accepted that the inside should be slightly warmer than the middle and outside of the tire.
I'm assuming this is just breaking the surface on what I really need to know now that I've got an accurate means of gathering data. Looking for some further insight on how to properly tune with the pyrometer.
Andy
I saw a good deal on Ebay for a $100.00
http://cgi.ebay.com/ws/eBayISAPI.dll...m=130129381908
12-26-2008, 07:38 PM
#7
Andy,
Congrats on a great gift. Pyrometers are really nice tools. You might know all below already, but if you don't:
May I suggest you also get a simple datalogger like a driftbox or equivalent (doesn't have to be a MoTEC or so..). When you combine it with the readings, it starts to make sense.
If your pyrometers reading window is a single one, I suggest you make a spreadsheet in Excel with boxes for each wheel marked with:
FL,[O,M,I] - FR [I,M,O]
RL [O,M,I] - RR [I,M,O]
Add general info to it: date, heat cycles, track temp, air temp, weather, wind and lap no.
And print out a bunch of copies.
You can then type down the temp readings in a intuitive way in the pit. Sounds like a small deal, but it helps to simplify pit work and later also connect the actual readings to your datalogger. Once you sit there with the papers and the datalogger - it's much simpler to connect the pyro readings with the data.
To get good use of it you'll need to get to know the tires you're running on. Tires have some times a bit different optimal temp span. Your tire manufacturer should be able to supply you with this information.
Pyrometer readings are not only for setting wheel setup and pressure. It's also a useful to find driver flaws. If you run with a team or know someone who drives well, start comparing your temps to theirs. Too low temps on the outside in the rear can for example be wrong setup, but also a result of the driver hitting the throttle too late at corner exit. Too low temps on the front outside (very common) is usually to slow corner entry. And so it continues.
Well, there's a ton to know there. Better get a good book. There are several ones and a simple amazon search would help you. Once you want to get a bit more advanced, you need to look more at vehicle dynamics in general, perhaps take a class or so. Some of the manufacturers can provide more data, classes if you run with a certain tire sponsor.
But for starters, start using it to get used to it and get to know what you're reading and why you get the numbers you do. It's a good way to get to know quite a bit. If you have any questions, feel free to shoot me a PM.
Good Luck and have fun
Congrats on a great gift. Pyrometers are really nice tools. You might know all below already, but if you don't:
May I suggest you also get a simple datalogger like a driftbox or equivalent (doesn't have to be a MoTEC or so..). When you combine it with the readings, it starts to make sense.
If your pyrometers reading window is a single one, I suggest you make a spreadsheet in Excel with boxes for each wheel marked with:
FL,[O,M,I] - FR [I,M,O]
RL [O,M,I] - RR [I,M,O]
Add general info to it: date, heat cycles, track temp, air temp, weather, wind and lap no.
And print out a bunch of copies.
You can then type down the temp readings in a intuitive way in the pit. Sounds like a small deal, but it helps to simplify pit work and later also connect the actual readings to your datalogger. Once you sit there with the papers and the datalogger - it's much simpler to connect the pyro readings with the data.
To get good use of it you'll need to get to know the tires you're running on. Tires have some times a bit different optimal temp span. Your tire manufacturer should be able to supply you with this information.
Pyrometer readings are not only for setting wheel setup and pressure. It's also a useful to find driver flaws. If you run with a team or know someone who drives well, start comparing your temps to theirs. Too low temps on the outside in the rear can for example be wrong setup, but also a result of the driver hitting the throttle too late at corner exit. Too low temps on the front outside (very common) is usually to slow corner entry. And so it continues.
Well, there's a ton to know there. Better get a good book. There are several ones and a simple amazon search would help you. Once you want to get a bit more advanced, you need to look more at vehicle dynamics in general, perhaps take a class or so. Some of the manufacturers can provide more data, classes if you run with a certain tire sponsor.
But for starters, start using it to get used to it and get to know what you're reading and why you get the numbers you do. It's a good way to get to know quite a bit. If you have any questions, feel free to shoot me a PM.
Good Luck and have fun
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12-26-2008, 08:30 PM
#8
Burning Brakes
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There are more opinions and theories about this topic that after years of racing I'm still not sure what the "best" method to interpret the information is. In the old days of bias slicks that ran little or no camber, an even temp across the patch made sense. After spending a weekend with the Dunlop engineers years ago it was made clear to me that when running radials, an even temp is not ideal. With the camber required to make modern radials perform, the inside will be in contact with the surface far greater than the middle or outside. This will "average out" that the inside will read higher. If you use the old method of interpretation, you would assume you have too much camber and dial out some. In actual fact, you would be losing performance. At least thats the way it was presented to me. I am far from a tire engineer.
12-26-2008, 09:05 PM
#9
Lifetime Rennlist Member
Even with bias slicks, you want a gradient according to Goodyear and their engineers at the track. It is not as drastic as what you want with radials, but it is still there. Maybe 5-10 degrees between inner then middle then outer while radials are generally 10-20 degree gradients. 20is pretty high but with some cars/tires that is the best you can do.
The real devil in dealing with tire temps is that they change very quickly. If you have ever seen real time IR data, the surface temp on a slick will go well over 300 deg in a corner and drop 50-75 deg in a second or two after exiting the corner. Surface temp is close to useless unless it is real time. You want a probe to read interior temp.
You need to get the data pretty quickly and without a cool down lap. For this you need someone in the pits to grab the data as soon as you come in, and do it off a hot lap. If the tire engineers say you should have a temp of 210 for a given tire, that means with a probe without cool down.
You are checking pressures and camber. But be careful about what the data tells you about pressures. Some low profile tires, which will have very stiff sidewalls, can fool you. Low pressures may create a wave (so to speak) across the tire and make the center run hotter than the edges, leading you to think you have too much pressure.
The best way to learn, IMO, is to find someone who has used pyro data for a while and get them to help. The more experienced folks always seem willing to help (unless you get within a second of their lap times for racing, then the help is a lot harder to come by).
The real devil in dealing with tire temps is that they change very quickly. If you have ever seen real time IR data, the surface temp on a slick will go well over 300 deg in a corner and drop 50-75 deg in a second or two after exiting the corner. Surface temp is close to useless unless it is real time. You want a probe to read interior temp.
You need to get the data pretty quickly and without a cool down lap. For this you need someone in the pits to grab the data as soon as you come in, and do it off a hot lap. If the tire engineers say you should have a temp of 210 for a given tire, that means with a probe without cool down.
You are checking pressures and camber. But be careful about what the data tells you about pressures. Some low profile tires, which will have very stiff sidewalls, can fool you. Low pressures may create a wave (so to speak) across the tire and make the center run hotter than the edges, leading you to think you have too much pressure.
The best way to learn, IMO, is to find someone who has used pyro data for a while and get them to help. The more experienced folks always seem willing to help (unless you get within a second of their lap times for racing, then the help is a lot harder to come by).
12-26-2008, 09:57 PM
#10
Drifting
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+1 With what magnus said, I diddn't suggest that as I thought it might start you second guessing yourself and your driving.
Back to what i was saying before, you must keep all other variables constant to accurately measure one, but i failed to mention that unless the nut behind the wheel is constant it all goes out the window. My coach told me when i wanted to get telemetry that unless I get to the point that every lap is within 1/10s of each other not to even bother with data. The same is true here.
Back to what i was saying before, you must keep all other variables constant to accurately measure one, but i failed to mention that unless the nut behind the wheel is constant it all goes out the window. My coach told me when i wanted to get telemetry that unless I get to the point that every lap is within 1/10s of each other not to even bother with data. The same is true here.
12-27-2008, 10:47 AM
#13
Lifetime Rennlist Member
12-27-2008, 05:38 PM
#15
Rennlist Member
So assuming that you're not part of a team and do it yourself, is this data going to be relevant? By the sounds of it the temps drop so quickly I would do temps all round first and then pressure? I guess one basic use will be determining if you have too much/little rubber on your car also.