The mere mention of “data acquisition” at a dirt track will illicit a variety of responses by the racers. Many of them might think that developing a data acquisition (DA) system will cost multiple thousands of dollars. Nothing could be further from the truth. In fact, I would suggest that you could build a basic system that can help you improve your team’s performance for less than it costs to buy the team dinner at the track concession stand. Yes, you will spend some money, it’s not going to be free, but that doesn’t mean DA is out of the realm of the weekly racer.
In the least complex terms, DA is a method of gathering information or data. It can be a computer-based system or a system based in pencils, pens, paper, and some stopwatches. The real trick is to just start gathering the data. Once you have the data you can start to ask and answer questions about your performance as a racer. Just like any other endeavor there are some vocabulary we need to talk about prior to going any further. For our conversation we need to define data. Data comes in two basic forms:
Continuous data is expressed as a number, it’s the number that your DA system is going to record and you’ll use this data or these numbers later as a basis for your analysis of your performance. A simple example would be lap times, spring rate of any given spring, crossweight, wedge, and so on. They are good examples of continuous data as they are expressed in numbers.
This tool makes measuring...
This tool makes measuring tire temperature a snap and it’s very quick.This model even has a red laser pointer to make aiming a snap. This tool is available at multiple sources all over the country. I purchased this one at Harbor Freight for less than $30. Can’t beat that with a stick.
Attribute data is just that, an attribute: good, bad, better, or best. We use words to describe an attribute. Attribute data isn’t what we should be using to tune our race cars alone, it’s a supporting role for continuous data. Taking notes about on-track performance that we express in words is attribute data, loose off, tight center, and so on. Those are attributes of what the car is doing on the track.
How It Was and Is
In the past, DA had to be done manually with a stopwatch, pen, and paper. But while many of us were hiding or content in the past, the future crept in and changed our world. These changes didn’t change the data, it was always there, and it just gave us more options to collect and analyze it. We now have the ability to ask many more questions of the same data set thanks to the advent of low-cost computers and software. This mountain of data allows teams to learn things about the car, its performance, and how changes they make effect both. We can not only discover if the car is simply faster after a given set of changes but where on the track this performance increase is occurring. We can use the answers a specific data set may give us to formulate more questions, to dig further into the performance envelope.
We can now look at g-forces through corners, down the straight, and under braking; we can look at suspension travel, driver input to various controls, brakes, steering, and shift points. As far as engine parameters, we can look at rpm, a variety of temperatures from oil, water, exhaust, and intake. We can even look at air pressures at a variety of body locations to verify wind tunnel data and get a better understanding of how pitch and yaw affect the car’s performance. How important this type of feature measurement is for the Saturday night racer may be a point of debate.
We can even look at the driver and monitor heartbeat and breathing; all it takes is money and an inquisitive mind. Granted, we weren’t able to track as many parameters using manual methods or look at as many dynamic variables. But the world has changed and we’re being offered a better way to gather the data we need to answer the questions we have about our race cars.
The reality is that many of these systems, while they offer mind boggling features and measurement opportunities, one has to ask the question: Does the local guy racing at the local track on Saturday nights need a high-buck DA system? In my mind the answer is yes. It would be very helpful, but I also think that it would be really cool to have an F40 Ferrari in my garage to run errands with on the weekends.
The durometer is used to measure...
The durometer is used to measure the hardness of rubber products. In the case of racing we use it to measure the hardness of tires. It’s pretty simple: The softer tires tend to develop more grip; and new tires are softer than old tires. But you need to balance wear and grip. The trick is to measure your tires and know when they’re too hard to give you good performance.
So what should the weekend warrior use to gather and analyze data? You may be spared the cost of any computer-based DA system because many local tracks and sanctioning bodies disallow the use of any computer data logging systems on your car on race days so you may be forced to go old-school. But that doesn’t preclude you from using all the tools at your disposal and still fit within the letter and intent of the rules.
As I spend a good bit of time at racetracks around the country I have the opportunity to speak to many racers, asking what parameters on the car they would like to measure. The answers were more common than different, which I found interesting. The majority of our racers were concerned with a minimal number of factors, rpm, speed through corners, braking performance, speed in mph, and acceleration rates. There was also a good sized group of racers who were interested in engine parameters. Every parameter that each racer wanted to measure was a real possibility.
When it came time to decide if they were willing to pay for the opportunity to measure all of the parameters they were interested in, their tune changed a bit. If cost was a driving factor, the variables they wanted to measure went down considerably. The list shortened to speed, rpm, lap times, g-forces, and possibly two pressures—one for brakes and oil pressure or possibly fuel pressure. When the questions were framed with a cost per parameter the number of parameters that were important was reduced significantly. Bottom line, many of the variety of measurable parameters are interesting but when cost was a factor the parameters that they wanted to measure were speed, acceleration rates, rpm, and lap times.
Checking and setting air pressure....
Checking and setting air pressure. What seems like a simple process is in fact frought with issues. The idea is to utilize a process that is performed the same by everybody on the team who may be called on to adjust and set tire pressure. You want to minimize variations in tire pressure caused by improper use of the tool used to measure air pressure.
So where do you start on your foray into building a better DA system for your racing program? The most obvious answer is a couple of stopwatches, some pens, and a spiral notebook are a great place to start. All of this can be purchased for less than $20 at the local Walmart.
Next, a tire temperature gauge is a tool that no race team should be without. We’ll not go into great detail about tire management; we’ve covered that in previous articles. The use of a tire temperature gauge is a tool that will help you monitor how hot your tires get and what the range of temperatures are across the tread surface. Today you can purchase an infrared thermometer for less than $25. I purchased mine for $23.99 at Harbor Freight, and it came with batteries; that’s just too cheap to not have one in your toolbox.
A durometer should be your next tool purchased as part of your DA system. A durometer is used to test the hardness of rubber. It’s a fairly simple equation, for your tires to work and grip the track they have to reach operating temperature. And the more heat cycles, the harder the rubber on your tires will get and the longer it will take them to get up to temperature. What happens is that the volatile light chemicals in the tire will out gas as the tire reaches temperature and the tire will get harder. The tires will not get as soft when they get hot so even when you get old tires up to temperature they won’t grip as well as a tire that has gone through a lesser number of heat cycles. A good durometer will cost in the range of $50 to $60. One can be purchased at almost any racing vendor or speed shop.
If you’re racing, you most certainly already have a tire-pressure gauge. It ranges in price from $50 to as much as $500 for the really fancy digital units. It’s your decision. Look at what your competition uses to get an idea of what your minimum requirement might be.
So, from an equipment perspective you could get by with spending less than $100 and get yourself all set up to have your own analog data acquisition system.
You’ll do a good bit of work...
You’ll do a good bit of work tuning the chassis and working on the drivetrain. You need to measure your performance so that you’re working toward a winning combination.
Next, prior to the next race, take your new spiral notebook, your new pen, and start documenting the starting point of how your car is set up. Start out with the date and track at which you’ll be racing. Document everything you can think of, such as:
• Tires, age and the manufacturer’s number, it’s a unique identifier on every tire, diameter of the tire at the pressure you will be running
• Wheels, condition, off sets, what your starting tire pressures will be
• Shocks, condition and where the compression and rebound are set (list this for each individual shock)
• Springs and their location on the car
• If there’s a sway bar on the car define the critical parameters, bar diameter, and how much preload is in the bar
• Weight of the car as a total, the weights at each corner and, just as a double check, the sum of the corner weights should equal the total weight of the car. If not, there is a problem some place (I have had the experience of these weights not adding up to the total weight of the car; that should be a warning that somebody’s scale is a bit off)
• Suspension settings, caster, toe, camber
This is just a beginning list but it should give you a good starting point for your DA system.
At The Track
A group of springs by the...
A group of springs by the trailer, a common sight. Which spring is the one that will help you deliver the winning performance? You won’t know until you start measuring and understanding when it’s the right time to use a specific spring. Measure, record, analyze, and do.
At the races, once again check all of your starting parameters and if anything has changed make the required documentation to the data sheet. You’ll also need to make some additions to the data sheet that you couldn’t make at home. For example, data, such as the type of day or evening you will be racing in from an environmental perspective:
• Ambient Temperature
• Starting pressure in each tire
• Starting tire temperature
• Track temperature, (it matters on the dirt too)
Once the car hits the track, start recording every lap and documenting the lap times. At this point it might be a good time to talk about on-track observations to go along with the lap times. The more notes that support a data set, the better the data. This is a great place to talk about the condition of the track. Was it heavy, dry, starting to take rubber, what was happening? “Why is this important?” you might ask. This gives you more insight to the performance of the car over a given set of circumstances and to the variables that you have no control over.
Once the session is over you need to accomplish several things very quickly after the car is off the track. These are time-based measurements, so getting them done as quickly as possible is important:
• Tire pressures
• Tire temperature (this is great information if you have the tools to do it, more on this later)
• Suspension travel (this can be measured by shock travel and doing the math that will equate to wheel travel based on the shock travel)
While you’re taking these measurements, the driver will have enough time to get out of the car remove his or her helmet, get a cool drink, and then it’s time to debrief your driver. How did the car feel? Was it loose? Was it tight? How was the engine running? Was there enough grip? Was the gear right? These are all things you need to get the driver to tell you. This is your attribute data set.
So which tire will be faster?...
So which tire will be faster? The one on the car or the one on the ground? The ability to make the right decision will depend on your ability to measure and turn those measurements into a winning combination. This isn’t rocket science or brain sugery but without some good data and analysis it’s just guesswork based on memory.
So, now you have the data sheet defining how the car was set up from a mechanical perspective, you have the raw numbers from the session in the form of lap times (the continuous data) and you have the driver debrief. But be cautious, many times when debriefing a driver he may be saying that he’s going flat out through a specific portion of the track when in fact he may be lifting and or applying the brakes without even knowing it.
If through your observations you noticed flames out of the exhaust as the car entered the corner or that the car’s attitude changed you need to discuss this with the driver. If the track can hold a car going in wide open and your driver has to let up or apply the brakes you have a problem that you need to solve. This is why notes are so important. The intent isn’t to catch a driver in a half truth but to really understand how the things you’re doing as a tuner are affecting the driver’s ability to drive the car.
Review the numbers. Does anything look out of place? Were there any unusual laps, slow or fast? Compare the lap times to your notes from the session. Was the driver in traffic or have a clear track? What about the line your driver was using? Was there a good bit of experimentation from a line perspective? Taking notes on the observations taken during a session go a long way to helping to understand the lap times you have just taken.
Remember this is the point when some racers take a set of data that is continuous and change them to attribute data. They have the temptation to say that only one lap was good out of a set of laps and then they miss the opportunity to really learn what the data set was telling them. All data has something we can learn about. Even if it tells us that we are going the wrong way.
Remember that not everybody can look at a set of numbers and glean the story they are telling. Many people are visual learners. Convert the numbers into a picture and you may learn more. Let’s look at a practical example of two 14-lap test sessions on the page to the left.
After the first session, the team decided that it would make some subtle changes to the car with springs and some tire pressure adjustments. The basis for these changes was made based on past experience with their familiarity with the changes that the track would go through as the night progressed.
From the combined data sets the team can begin to make further adjustments to the car in the days following the race. Repeating the procedure each week will build a comprehensive portfolio of information.
The addition of DA to your racing program doesn’t have to mean high-dollar computer systems and specially trained people. It does mean that you may have to place a bit more rigor into your racing program to start measuring your various systems that make up the tuning process itself. Reducing the variability within your racing processes will result in better finishes and improved reliability.Your ability to define and understand what is going on with the car starts with having data and learning how to ask questions of the data and making your tuning changes based on what the data is saying.
The 14-lap sessions we looked at have much more information than just what we are seeing in the raw data and in the graphs we created. As you gain a further understanding of the relationships between tire pressure, tire temperature, and rubber hardness as it relates to lap times you’ll gain further insight to the tuning processes. You’ll understand how spring rates in the car and in the tires can have a very strong effect on the overall setup and its performance. The point to remember is that your race car is a collection of many systems interacting at the same time. It’s your job to define and control the various systems to improve the performance of the car.
As you start gathering data in your spiral notebook you may want to transfer the data to a PC or notebook computer. You may even get a copy of Excel with the machine and that software package has more than enough statistical analysis power to do some very specific data analysis that will help glean even more information out of the data you’re collecting. I’ve been seeing more and more guys at the track with computers in their trailers and they aren’t playing video games. They’re winning races. There’s no reason you can’t do the same.
Raw Data: It’s clear from this data set that the driver was able to improve the lap times up to a point. Then the car started to slow down. Why? It’ll be difficult to assign a cause without the notes and the driver debrief. It may have been a very typical or normal occurrence and you just didn’t know it was happening until you started taking notes and measuring the car and driver’s performance. Then again it might not be normal.
|Lap #||Lap Time|
|14||15.448|A Graphical View:
With the data in a more graphical perspective it was very clear that the car was getting faster each lap than there was a drastic change that occurred on lap 12 and the car started to slow. The graphical perspective makes the change very clear and dramatic. What happened to make the car start slowing down? Was the car starting to fall off due to a mechanical reason? Did the tires over heat or was there traffic that was causing the car to slow. Whatever the reason we had a 0.8-second fall off and that wasn’t good. The other question we need to ask is why it took 11 laps to get the car up to speed? The challenge for the tuner and the team is to understand how to make the correct adjustments to get the car up to speed faster.
Raw Data Session 2: The changes the team made worked, but the car still took 8 laps to get up to speed. The team is going in the right direction; and the measurement process was helpful for the team to ask better questions and get answers.
|Lap #||Lap Time|
|14||14.907|Graphical View Session 2:
The graph of the second session tells a very different story of the car’s performance. It started out faster but the transition to the quickest lap still took 10 laps. It was clear that something wasn’t happening quickly enough with the car.