Data Acquisition, fact or fiction, requirement for any car, or advanced.

[clarkspeed]

Starting a new topic based on hijack of Ben's FP 280 thread. There are a couple people, including me, building competition cars or running them at this time. Scope of this thread should define minimum requirements of an autox, time trial, or race prepared Nissan Z car along with advanced path for future upgrades. But mostly minimum requirements suggested for competion based applications. Hence the post under the Motorsports heading.

 

First observation, amazing how long it's been for activity on this topic. 

[clarkspeed]

My first comments are I posted a primer on analyzing basic data a few years ago but cannot find it on any of my searches. Please post a link if found.

 

Next comment, data collection and analysis should be super quick, accessible, and comprehensible for autox and time trials. 

 

Next comment, overall data analysis is 80% driver, 20% car 90% of the time.

 

And finally, if starting out, what data is needed? Where would you start with a new car and new driver? 

[jhm]

Thx for taking the time to continue this important discussion, Clark!

 

At the risk of publicly making a fool of myself, I'll go first.  I was thinking that it would be useful to talk about how much great data can be collected & recorded with just simple hand tools, vs sophisticated data loggers, video devices and smart phone apps.  Attached is photo of roughly $60 worth of simple tools readily available from multiple vendors (including your local hardware store).

 

As @clarkspeed mentioned in a previous thread, there’s no limit to amount of data one can easily collect & record at each and every track session to help improve your driving  performance (e.g. lap times, driving smoothness, capability of the car, etc). 

 

Here are just a few of the data parameters that I have found useful, FWIW:

 

Suspension setup.  This is a BIG system, with LOTS of variable parameters that can be measured and tuned to achieve your best performance.  This can also vary widely – no single setup will rarely work optimally at every type of event (auto-x vs road course vs straight-line vs oval track, rough surface vs smooth surface, variable weather conditions, etc, etc).  Camber (front and rear, left and right), caster, front-end toe, ride height (front and rear, left and right) can all be measured with simple tape measure and angle finder.  A cheap, accurate digital angle finder is $20.  A tape measure and some ordinary string can be used to accurately measure your front-end toe; and after doing it a couple times, it becomes second nature to quickly and accurately measure and adjust your toe settings.

 

Tire pressures and temps.  ALWAYS measure tire pressures, hot and cold; to determine what pressures work best for any given surface and suspension setup.  Equal pressures on all four tires is not necessarily the best solution….you can vary front vs rear pressures and right vs left pressures to achieve different handling characteristics.  When measuring tire temps, use a probe-style pyrometer vs surface temp IR gun.  The IR gun can only measure surface temps on a tire, which doesn’t give an accurate indication of a tire’s internal temperature, which is what’s really important.  Additionally, the tire’s surface temperature can change significantly from the time you exit the track to when you actually take the measurement, vs the internal temp remains quite consistent for some time after exiting the track.  A cheap, accurate pyrometer and tire probe costs $20 and a good tire pressure gauge is $10-$20.

 

An IR gun DOES have many uses, and can be had for $20.  It can measure track surface temperature, which has a huge effect on tire performance (especially short-duration events, like dragracing, top-speed comps, auto-x or time trials).  IR guns can also be used to measure brake temps, differential temperatures, header temps (including individual header tubes) and many other useful mechanical parameters on your car.  It can verify that your coolant temp and oil temp gauges are operating correctly and accurately.  Ambient weather condition will also have an effect on the car’s performance; so be sure to record those, as well.  Ambient temperature, sunny vs cloudy, altitude density and precipitation are just a few of the many weather parameters that can factor in to affect your car’s performance, and these parameters are all readily available with just about any good weather app or website.

 

Sorry for the long-winded, and rambling, response.  These are just a few examples of the data that can be easily and cheaply measured & recorded; and I’m sure that my feeble-minded reply is missing a whole bunch of stuff….others will chime in, I’m sure.  This is more just to get the discussion going.  I look forward to the ensuing discussion and sharing of information!!   

Edited September 8, 2022 by jhm

[clarkspeed]

No, THAT IS AN EXCELLENT RESPONSE, and the perfect place to start the discussion. What is data anyway? Facts, figures, numbers, words, pictures, video? It's all of the above. Think of it as something to save that describes something that happened that you can refer to later. 

 

So let's start with the bare minimum. A system for collecting data is #1. Pad and pen, track maps, spreadsheets, etc. Whatever works for you and find a way to keep it organized. I still use a notebook with a pen to record everything I can think of of during a race weekend. Weather, Temps, problems I had, what bolts I had to tighten, things I need to pack next time or discard, parts that need to be replaced, parts I did replace, how the car felt, etc. After a few entries, some patterns appeared. I developed a pre race check list, and a maintenance check list from this along with many other insights. And my main focus is creating an action list to implement before the next event. What do I want to change and why.

 

If starting out, I suggest trying to record everything you can think of. How to drive the track, how you were feeling that day, what felt good about car and what did not. I used to scuba dive and did the same thing in my dive logs. Some of my entries are numbers, some look like I am writing a diary. And they reflect other sources that are disconnected, like a note that I took video or recorded something with another system and it was successful. Over time you get a better feeling for what you really need to write down. I review it after the event and address the action items. Then I review it again before next event.

 

I stipulate these are only my opinions, but I say you need to start with the above before you go to step #2, which looks exactly like the picture posted by jhm.

[clarkspeed]

And more food for thought. When it comes to data, I have 3 contradictory quotes that all apply. They hang on my wall at work so I read every day. 

 

"You can't improve what you don't measure" - Drucker

 

"You can't fatten a calf by weighing it" - Anonymous 

 

"Not everything that can be counted counts, and not everything that counts can be counted" - Einstein

[JMortensen]

I need a new phone. Have been threatening to buy some sort of cheap DA setup for about 10 years, haven't made a purchase yet. Would like to go Apple on the phone because of the scanner feature. At one point there were a lot more apps for droids than iPhones.

What's the situation like now? Does it matter?

[NewZed]

What do mean by "Data Acquisition"?  Things have advanced dramatically even in just the last couple of years, for "phone" apps and standalone devices.  It's pretty incredible.  

[Ben280]

@JMortensen For phone based DA, Android is still the best bet. Solostorm, which is the defacto standard for autox, and has a very good time trial/hill climb mode is only available for android. Similarly, RaceCapture is only available on android mobile devices, although possible to run in a mac desktop environment. In general, I think a dedicated hardware device is going to be more accurate and give you real feedback vs a phone. Devices like the RaceCapture Pro series, which is essentially the megasquirt of data loggers is the easiest way to get a high quality accelerometer and GPS into a car I think. Look for stuff like CANBUS, wifi networks or bluetooth to connect to things, but I (and others) have found that phones just don't have accurate enough accelerometers or gyros, and too low of a GPS refresh rate to be useful for positional information. 

 

I ran Solostorm and a RaceCapture Pro2 for years in my car, and am finally moving away from it to a dedicated logging dash. Good stuff IMO. 

[Ben280]

Responding to @clarkspeed initial question, "what data is needed starting out" I have thoughts. 

 

In addition to @jhmcomments about tracking suspension and temps which are fantastic for a consistent car platform, TIMING AND VIDEO! If you don't have reliable timing you have nothing. Particularly for a competitive or track environment, and are seeking improvement, reliable timers will tell you if you did something correct or incorrect on that lap. Devices like the AIM Solo2 solve that problem quickly and easily. This also allows you to compare your times with others, and get a sense for how fast you should be able to go vs how fast you are going. Video is crucial as a learning tool, (and to show your friends), so you can remember back and see where things went wrong. Our brains don't do well recalling fast paced events, and often times that lap where you thought you were fully on the apex of every corner and pushing as hard as possible, will look tame, and have obvious mistakes you can improve upon. Video also allows you to share something with a coach, buddy or new track friend to help improve. 

 

Moving on from the basics, I want to start capturing granular data about the car's driver influenced performance. Things like cornering G, braking and accel G, TPS position, brake pressures (and by extent how much brake we used) and steering angle. Those are in order of complexity to add. G force will be easy, and generally handled by the timing device, assuming you got a good one. You did get a good one right? Harry's Lap Timer isn't viable in a data discussion. TPS will be tracked by most ECU's, assuming you are running any kind of stand alone. Brake Pressure is "easy" to add with a little plumbing and some new wires to the data logger/timer. Steering angle is tough, but I have faith in you. With these, we can see how hard we are accelerating, when we are accelerating and for how long, where we brake and how much, and where we turn. We can use all this to start tuning consistency and identifying more granular trends. Did the video show snap oversteer out of a corner and a slow time? Our data trace shows that on one lap we were longer at a high throttle percentage but speed doesn't pick up accordingly. We can go back, and see that we applied less brake pressure on entry, our corner exit speed was 5mph higher than other laps, but we didn't change our throttle behavior on exit. Easy time pickup with some very simple tools. You can do most of that with GPS and accelerometers alone, but more sensors allow additional granularity. 

 

Moving on from there we start spending the big bucks, and really, it's not appropriate unless we are racing for some real stakes. Things like linear shock pots, radar ride height sensors, IR/temp sensors for tires and brakes, engine health monitoring etc. We can go as wild as we want, but unless we are 100% fully optimizing a chassis, it's fully overkill. 

 

One thing to think about with Z's or any other car, as we add components, can we get those components to talk via CAN or other protocols to each other, and get important data out of them. New cars have more data than we know what to do with, old cars we can spec up to get what we need!

 

[JMortensen]

Thanks Ben.

NewZed, I'm looking for BASIC data. I don't really know what I'm looking for other than to capture data. I can do tire temps and pressures and that sort of thing manually, but I'd like to have video with g forces, speed, real basic stuff. Figure I can make changes and see if I see a difference in lateral or longitudinal gs. Was hoping to get friction circle data out of whatever I get.

I'm not interested in all the linear pots and all that, just too complicated. I do find it somewhat amusing that you can take a new Vette, or even my '07 GTI and plug a datalogger in and it will grab all of that info from the stock sensors. Reason number 487 to give up on the Z and get a new car to race. When I race the GTI it's just so... FWD.

[Ben280]

I think you would be really happy with a solostorm setup. My racecapture setup was great for a car running stand alone, you can capture CAN signals with it and pull the data you want out of it. The app itself is fairly friendly too!

[clarkspeed]

Thanks all for adding to discussion! Very good comments on phone based systems of which I have not played with for 7-8 years. I have been putting off my 2nd installment in this series, but now motivated to type it up. It will be the next step beyond my 1st post.

 

In the meantime, I have an older Race Technology DL1 currently for sale on Ebay at $100 if anyone is interested in moving up to something VERY powerful. I tested it and it works great. Contact me and I will be happy to answer questions about it. For a Hybrid buyer, I will even put some analysis setups in with it.

 

Eventually I intend to make a number of posts with very good primer on progression into data systems.. what you need at what level you are. Just need to get all this work travel behind me.

[jhm]

Yes, many thanks to those that have joined and continued this discussion.  @Ben280, as you probably figured out...my original intent for that early post was mostly to get the discussion going and illustrate how much useful data can be gathered with simple inexpensive hand tools.  Thanks very much for continuing the thread and bringing more sophisticated computerized tools into the discussion.  Very interested to hear your thoughts on iphone vs Android organic capabilities.  As someone who was dragged into the smartphone world kicking and screaming, I personally am very ignorant on the inherent pros/cons of the current fleet of modern smartphones.  I 100% agree with you that the organic location-finding capabilities of many (most?) cell phones is lacking; but that can be overcome by pairing a precision GPSR with your smartphone...true?  I've been using a Dual precision receiver for the last couple years with my iPhone, and have found my lap and sector times to be quite accurate (comparing the results in phone app vs light-beam timers).  FWIW, Track Addict Pro and Harry's Lap Timer have been working well for me personally....but there's a BUNCH of apps out there to choose from.  Fully realize that I need to bite the bullet and buy some more sophisticated data logging equipment; so I appreciate your thoughts on which systems you've had good success with.  Thanks!

 

@clarkspeed, many thanks for helping guide this talk.  I'd like to chat with you regarding that DL1 unit for sale.  Will PM you separately.

[Ben280]

@jhmThe basic tools you mentioned are often more than most bring with them to the track, and they can be super illuminating for issues. 

 

I think the iphone vs android debate boils down to which you have. If we are trying to bring folks into the data-sphere, lowering barriers to entry is huge. Having ANYTHING for timing etc, is going to be helpful. If, like Jon is, looking for a new device, I think Android is the better choice, since the two more involved apps I am aware of for this, on will only work in an Android environment. Solostorm is not an inexpensive situation ($220: https://www.petreldata.com/product/solostorm-autocross-data-logger-for-android/) but it is very powerful. Other tools like Harrys Lap Time or Track Addict Pro are good, but do rely on the inherent tools built into the phones. 

 

If you have a bluetooth OBD-II scanner and a bluetooth GPS, that will get you much further than most. Since most Z cars don't have OBD-II however...   

 

For my rebuild, I looked heavily into a AIM system. The Solo-2 DL is a really good option that doesn't require a lot of adding in, and the AIM telemetry software is really well supported. Ended up going with MOTEC since their system is also really well supported, and a few folks I race with quite a lot also run them so it will be easy to get support and compare notes. 

[tube80z]

I was going to do a lot of replies but I'll just distill my relationship with data and how I've found it useful or not useful if that's the case.  I mostly autox and hillclimb, but I help friends at circuits and have been exposed to really high levels of DA through my professional work.  I've taken a ton of data classes over the years like Claude Roulle's optimumG training, John Block's excellent data courses, a number of race engineering vehicle dynamics seminars, etc.  I also have an excellent collection of well-used books into what's needed.  For me this is something I like and enjoy learning more about and digging into.  For a lot of people this is considered too technical and all they want to do is drive and have fun.  If you fall into the latter category you can quit reading :-).  Please keep in mind this reply is for people with older cars that don't have CAN/ODBII.

 

The single most important thing you can do is to keep records.  At the minimum you want to record the course, lap times, basic weather info (warm dry vs wet cold) time of day/date and what needs to be fixed so you could drive better or make the car faster.  If you have an event or option to do practice or fun runs you can use those to make changes and then see if that helps or not.  How to make easy adjustments to your car to figure things out could be its own thread.  It also important to get pictures from the event where you can see your car loaded up in a corner as well as those that are faster than you or in the same class.  There's a lot that can be learned from these photos.  And ideally have someone take video of the same cars and if possible use a tripod so you can tell what are and are not trying to see if the car is hopping or the camera operator(phone owner) had too many lattes.  These days almost everyone has a camera and most of these also capture video and those get shared on social media, which makes it easy to collect this info.  

 

One really cool trend that I think helps is the emergence of many packages that merge data and video.  There are now packages that exist that let you use nothing more than a GoPro camera as a data logger and you can get some very basic info.   As @Ben280 mentioned for autox there's solostorm, garmin's catalyst, Aim's solo, Apex Pro, phone apps, etc.  There's no right answer for what is right for you.  I would say it helps if you have the same thing as other people and you have a way to sync the data to video.  The latter is extremely important if you want to know why a run was better or worse.  The hard part is getting feedback on what you need to do to improve/go faster.  For autox it's impossible to read a dash on most courses, but a green or red graphic or LEDs is something you can see if this is important to you.  I can also tell you that many apps that use GPS as the main source of data often fail when hillclimbing.  Here in the PNW a number of events are remote (no phone service) and have full growth over the road so no GPS.  

 

Circuit lapping (HPDE, races, time attack, etc.) is often where you'll see the mid-range systems used.  It's still possible to use a number of the same autox systems they usually don't capture enough data.  These are where you normally see the squiggly lines that make some people so excited.  The good news is the low end has been pushing the middle tier options to include more video capabilities.  My experience here  is mostly with Aim systems and some of the older Race Technology systems (like the one @clarkspeed has that @JMortensen should buy :-))  If you're just looking to get better and do HPDE then the garmin catalyst and similar competitors will be helpful.

 

With any of these systems the challenge is how to use the data to get better.  In autox you don't have much time between runs so any analysis has to be fast, which a few of these systems are better at.  For circuit racing if you're a one-man show then you often have a lot of prep between runs and data still needs to be quick but you will have a little bit more data to you should look at like engine/car health.  And above these are truly fancy systems that often have a single person looking after them and helping with the analysis.  I'm not going to mention these as there are probably 5 people that would be interested.

 

So if you're still hanging in there here's what I think will be the most helpful.  

 

Starting out and I want to get better (most basic system)

1.  Video pointing out of car that captures run and the main driver controls

2.  Second video source capturing feet on pedals (or the BS on being flat in that corner show)

3.  Speed captured against distance travelled (not time).  This is important for comparisons.

4.  Lateral & longitudinal acceleration.

 

Consider adding steering, and brakes to the above list.  On the brakes side it can be done one of two ways.  You can look at the pedal movement and/or you can add in brake pressures.  If you go for pressure make sure you are measuring caliper pressures and not master cylinders if you use a proportioning valve.  This will give you a system you can use to learn to go faster.  If you are thinking about doing any of this it pays to educate yourself on youtube or take a class about the system you have.  A few of the companies offer webinars and paying a couple hundred for a course can put you years down the road from what you'd learn on your own.  Unless you have a friend that is into this and can help. 

 

Being this is hybridZ there's still one important topic we need to discuss.   @Ben280 mentioned additional sensors and the costs associated.  I have some great news.  You can use stuff from a JY for a lot of this and it's just a matter of calibration that you need to do.  Here's a handy list.  For distance (shock pots, steering, throttle, brakes -- you can use a throttle position sensor.  When using with shocks, steering, or other linear source you will need to create a linkage that rotates the sensor.  RC parts often are very useful.  For pressures you can use JY sensors (Bosch) from any of the newer cars that have ABS.  There are a lot of cars using these today.  You can also get another cool part called an IMU.  These are often used as part of the vehicle stability systems that all new cars are required to have.   Time to stop until there's more interest.  

 

More later ...

 

 

 

 

 

Edited October 31, 2022 by tube80z
posted before finished

[NewZed]

Not an expert in race stuff, but just a short observation.  GPS stands for Global Positioning System and it uses satellites.  Cell phones can use triangulation from cell tower signals.  I have an early Garmin GPS device that actually shows how many satellite signals have been acquired and where in the sky they are.  https://www.gps.gov/

 

Anyway, "GPS" for phones might not be real GPS.  I do know that I can get a "GPS" location on my phone even though I don't show cell service, like on a hike in the hills.  But I don't know if it 's because I have a cheap cell plan but it allows GPS for Google maps using cell towers, or if it uses satellites.

 

And today we have Starlink.  And Motorola's satellite system, the original plan for traveling portable phones for the masses, is still out there too.

[NewZed]

Here's more on locating.  You might have meant this already, I'm just posting for clarity, for the discussion.  There's a latency involved.  Kind of complicates things for racing.

 

https://www.androidcentral.com/how-does-gps-work-my-phone

 

-  advice from an amateur woodworker (the guy that wrote the article above).  Don't know how deep it is.  I just know that things keep changing.

Edited October 31, 2022 by NewZed

[clarkspeed]

On 10/30/2022 at 10:38 PM, NewZed said:

 

-  advice from an amateur woodworker (the guy that wrote the article above).  Don't know how deep it is.  I just know that things keep changing.

 

My wife says that all the time! 

.

.

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(I could not resist)

 

Clark

[clarkspeed]

This is what I plan to cover in more detail.

 

#1 tire pressure, temp overall, temp across. IR temps of various components. And gauge read outs. Continuation of my last post and JHM post. Video.  No data ack system required.

 

#2 Data you need vs. Data you want. Autox, hill climb, rally stages, hot lapping, racing, sim racing, testing. Intro to electronic data ack. How much should you spend?

 

#3 Basic systems. Basic info. What to look for. Car vs driver. Comparisons with self and others. Trends. Consistency. Money trace (speed vs. Distance) G circle. Keeping it simple so everyone can use and understand basic info from any system. 

 

#4 Advanced, math channels explanation, braking, kpi's for track, car, and driver.

Shock tuning, combined with other chassis analysis. Not too deep here, but awareness of possibilities.

 

My posts will be very generic. No references to manufacturers or systems to get the data.  I will rely on the community to fill in the blanks for the best or optimum or cheapest way to get there. I am no expert on everything out there. I have played with AIM, MOTEC, and Race Technology analysis software which are all similar. And I have been studying basic analysis recomendations for the last year which kind of gave me a appreciation for the basics, and triggered me to start this thread. With the exception of post #4, most all data is available from phones, AIM solo, Garmin, or similar inexpensive systems. 

 

You guys fill in the rest, which you already are!

Edited November 1, 2022 by clarkspeed

[clarkspeed]

I will dig a little deeper into data collection systems in future posts.  After I thought about it, it just seemed like a disservice to jump into higher level stuff without first covering the basics. There is a huge amount of insight than can be gained through a little discipline and basic tools.  It is best to exploit these to the fullest before moving up the ladder to more advanced systems.

 

Post #2 – The most basic data you should work with

As a continuation of my first post on discipline and making a habit of recording data, I would like to go a little more in depth on what data is important. By far the most important component of a competition car is the tire.  It just so happens that it is also the most complicated thing on a car.  A tire is composed of fused polymers and chemical additives that once cured exhibit certain characteristics that directly affect the grip and performance of a car.  And to make things even more difficult, tire manufacturers cannot predict what the final performance characteristics will be.  It is not uncommon for a new race tire compound to be slower than the compound before, deteriorate quicker, require a different set up, etc.  And tire manufacturers do occasionally change compounds.  If you are at the sharp end of the stick, you will sometimes see manufacturers release new compounds just before the SCCA Runoffs each year.  Sometimes everyone switches over, sometimes not.  You don’t have to look any farther than today’s modern F1 racing to see how a team’s tire strategy can make or break a weekend.  Just a few degrees of ambient temperature change or track moisture can make a tire compound undriveable, and they must race with at least 2 compound changes during a 2 hour race. And by now it should be obvious if you change tire brands you will definitely have something different to deal with when hitting the track.

 

So let me make a couple clear statements which will drive our future priorities on data collection.

1.       At amateur levels of competition, the DRIVER has the most influence on competitive lap/sector times. Sometimes up to 70-80%. There is no better way to knock whole seconds out of your lap/sector times than becoming a better driver.    

2.       Following driver ability, most races are won and lost based on the ability to extract the most out of a tire, as opposed to horsepower.

So, getting back to basic data, our top priorities are making sure the tires are happy and somehow measuring the driver.  Luckily the first step does not require a large expenditure or knowledge.  You are probably already measuring the driver.  If involved in competition, you are already comparing yourself to others.   As mentioned in my first post, keep a record of where you are at.  Here are some examples:

 

1.       Lap times at a circuit and why they were slower or faster than previous run or visit to track.  Weather, perceived surface grip, struggles on track are good details here.

2.       Your ranking against your peers. Getting better or worse?

3.       Get some segment times, have someone with stopwatch measure your time within two key points and other cars at the event.

4.       Target another driver who often attends your events

5.       Try something different on track and see if the lap times changed for better.

 

Pretty basic stuff but can reveal some trends.  Recording this kind of info does 2 things. Forces you into setting goals, and hopefully understanding why sometimes you are faster or slower than other times.

 

Next up it tires.  As mentioned, a difficult subject even at the most basic level.  So let me make another all-encompassing statement here:

 

Every tire has a happy spot related to temperature, pressure, and camber where it makes the most grip.

 

Again, not a lot of special tools or fancy systems required at the basic level.  And depending on how restrictive your class is, this may be as far as you will ever need to go

. 

The first thing I will talk about is pressure.  As mentioned, there is an optimum pressure you want to hit.  What is that pressure?  Without getting into too many details, you will need to find this out for yourself and that can only come with testing.  A tire works best when hot, so that is where you when you want to measure the pressure.  Tire manufacturers often provide a window but this can be misleading without knowledge of the weight characteristics of your vehicle.  And manufacturer provided info will lean on the side of safety, so usually a little higher pressure than required.  So to start out take recommendations wherever you can.  Online forums, friends, competitors, and the manufacturer info. Then test for yourself.  Don’t make small changes at first, for a radial try what you think is a good number then at least 5 psi above and 5 psi below.  If you can’t feel anything, try 8psi delta. Record how it feels and which was fastest. Most likely you will find your happy middle number will need to creep up or down. Then over time you can fine tune with lower increments until you are satisfied.  And if running a spec class, it is possible that tire pressure is the only thing you have to change handling characteristics.

 

But “hot” pressure can depend on a few factors.  Air expands as it heats up, so where you set your cold pressure will be less than the pressure you read as you come off course.  With the exception of tire warmers, most everyone will need to predict a cold pressure to start with and measure the pressure as soon as you come off course.  So here are the things to consider:

 

1.       Tire air moisture content.  The wetter the air, the more expansion.  If you use the same air source over and over, this should be consistent.  If you would like to limit the amount of expansion, use a compressed air dryer or bottled gas.  Air is mostly nitrogen, so switching to pure nitrogen is no better than just using dry air.  You can build your own compressed air dryer on the cheap using silica gel desiccant.  We have also used scuba air.

2.       Ambient temperature has to be adjusted for. Setting your cold pressures on a 40 degree day will be lower than on a 80 degree day.  If you normally allow for 5psi of pressure rise, you may need to allow for a 10psi rise. Be careful here, the fastest way to heat a tire is pushing high slip angles, but if it is really cold you may need to bring up the temp slowly before attacking a corner.

3.       Use a reliable pressure gauge that is calibrated.  0.1-0.2 psi resolution. Don’t be afraid to check it against other gauges over time. Never use a friends gauge to set your pressures unless you can verify it reads the same.  Repeating the same pressures you like every time is important.

4.       Your goal should be predicting the hot pressure +/- 1 psi or better.

5.       And as a side note, swaying back and forth to warm the tires before a race has limited impact.  You can also use the brakes to create slip angles and put heat in the tires with the added benefit of getting some residual heat through the rotors and wheels. Often this is more beneficial.

 

Next to consider is overall tire temperature.  A tire pyrometer works best but a cheap IR gun also works in a pinch. Believe it or not, this is the simplest thing but many have problems here.  Most pure race tires operate in a range from 170 to 210 degrees F.  I don’t know what the current crop of 100 and 200 TR tires operate at.  So if you are running an R compound or slick, and you measure 130, you are not in the range of most grip. There can be many reasons for this, the least of which is not driving hard enough.  Too stiff a spring rate and excess shock valving can also show up here.  Along with a damp cold track.  If you can’t get enough heat in your tires most other testing is useless.  Remember to take good notes.  Tires that are too hot can also cause handing problems and deteriorate quickly.

 

Next up is temperature across the tread.  This is where you can really pick up some grip if driving a stock based car.  Street vehicles have only a small amount of positive camber allowed within their nominal alignment settings.  When a car corners aggressively, the body lean overcomes this angle and most of the weight transfer ends up on the outside edge of the tire.  The tire contact patch area becomes very small.  Continue and you can cord the outside edge very quickly when track driving.  I am not going to go dive very deep here, most race rules allow for some kind of camber adjustment to compensate for this.  Even restrictive spec class rules allow you to loosen every thing up and maximize the bolt hole runouts.  Better than nothing.  Anyway the idea is to have the tire tread as flat as it can be during maximum cornering.  This usually requires some positive caster, especially on strut based suspensions.  One of the best ways to measure this is by taking tire temperatures when exiting the track.  You are looking for even temperatures across the tread measured on outside, middle, and inside.  It is generally accepted 10-20 degree more on the outside measurement compared to the other 2 is about right to maximize the contact patch.   Some considerations for temp measurement:

 

1.       Take temperatures as soon as you can when safely exiting the track from a hot lap all the way up to the last turn.  The tires will cool down very quickly on a cool down lap or a long straight before the pits.  Best is to test on a skid pad.

2.       Take temps the same way every time and measure pressures following.  A recording tire pyrometer works wonders here.

3.       Record everything.  Adjust camber accordingly.  Don’t forget to set toe also following a front camber adjustment.

4.       LOOK AT THE TIRES!  I mean really look close at how they are wearing.  Make notes, take pictures. Look for evidence of over driving, bad camber, flat spots, wear rings, excess or inadequate pressure.

 

Other data to think about includes various temps and gauge readouts.  Ever look at an oil pressure gauge and wonder if it 5psi lower than it should be?  It’s a good idea to make a note of what your various gauges read nominally.  Maybe even put a little piece of tape on the glass as an indicator.  Just knowing there is oil pressure is not enough.  Better to know immediately if there is a couple psi drop or a few degrees increase in temp.   IR guns are good for this also.  Cylinder head temps, transmission temps, differential temps are all good things to record and refer back to if needed.

 

Enough for now.