For this month's cover story, we put a new lap timer and data acquisition system to the test: Aim Sports' beautifully constructed Solo unit. This compact device uses a 10Hz GPS chipset and onboard accelerometer (or g-force meter) to not only track your vehicle's position around a racetrack 10 times per second for highly accurate lap times but to also record all sorts of other valuable data, including lateral (cornering) and longitudinal (accelerating and braking) g-forces. Opt for the DL version and you've also got fully integrated data from all your vehicle's onboard sensors by simply connecting the Aim unit to your car's OBD-II port with the supplied cable. How cool is that?
Or perhaps the more appropriate question is: How useful is that? For the average HPDE or lapping-day enthusiast, data acquisition beyond a basic lap timer may seem a bit intimidating, partly because at HPDE events, they don't want you recording lap times and getting too competitive about your pace around the circuit. But once you've graduated to time attack competition or any other form of racing, you'll soon learn that accurate lap times and at least some basic data acquisition and analysis go a long way to improving your on-track performance as a driver and your car's setup.
There are a lot of different ways you can use a data acquisition system like the Aim Solo. First of all, there's the in-car lap timer experience (and we love that the Solo has a rechargeable lithium battery built into it, so there's no annoying power cord flopping around while you're out on the racetrack), in which you've got the display suction cup mounted to the inside of the windshield so you can quickly and easily see what your lap time is, and in the case of the Aim Solo, it also does predictive lap timing, so it constantly updates you during a lap to let you know what it's projecting your lap time to be when you cross the start/finish line. You can also opt to have the Solo show you a predictive lap time based on how much faster or slower your pace is versus your best lap so far.
You can use the data to not only analyze your own driving but also to compare setup changes.
This type of instantaneous feedback during a lapping session can be really valuable, since you're getting immediate input on whether that late apex, new driving line, or shock damping adjustment helped you carry more speed through the corners and down the straights. But it can also be a distraction if you find yourself constantly glancing at the display rather than focusing on the road. Have a bit of discipline by only checking it on longer straights, though, and it really is a very safe and effective way to get some data-based feedback. It's almost like having an in-car instructor, but without the added weight, distracting chatter, or Cheetos breath.
Once you've parked the car, things start to get really interesting, if you're willing to spend the time necessary to acquaint yourself with the data analysis software and learn how to analyze and interpret the available data with it. The Race Studio2 software that comes with the Aim Solo is some of the best in the business, and I've tried most of them. I find Aim's software to be far more intuitive than most (though it does take some time to figure it out at first), and Race Studio2 has a lot of useful, built-in functions that let you quickly and easily break down the data into highly informative reports, tables, or charts that summarize key data for your fastest lap or your entire lapping session.
Keep in mind, you can use the data to not only analyze your own driving but also to compare setup changes like we have for this cover story, to compare vehicles like we have for the cover story, or to compare drivers in the same car (which can be a very useful way for a faster driver to show a slower driver where he's losing time). If your car has an OBD-II port and you want to maximize your analysis options, then using the Solo DL or a similar system is the way to go, since being able to review rpm, throttle position, and brake pedal position is highly valuable. Knowing something as simple as what percentage of a lap you're at wide-open throttle can be extremely useful, for example, since the longer you're at full-throttle, the faster your lap is likely to be.
But even without OBD-II data, our Solo unit allowed us to spot key differences in the performance of the two cars we tested for the cover story, as well as identify some subtle differences in the way each responded to the upgrades we made to them, as you'll soon read. That's because with the Race Studio2 software we could overlay the speed and g-force data on the same graph for the fastest lap in each car, making it very easy to see, for example, which corner each carried the most speed in and which straightaway each accelerated more quickly down. Similarly, we were able to overlay the fastest stock lap for each car against its fastest suspension upgrade lap, making it easy to see how its on-track performance changed as a result of the modification.
There are some excellent books and online tutorials about how to analyze data acquired using a GPS- and accelerometer-based lap timer like our Aim Solo (including video tutorials for you visual learners out there), so I'm not going to go into any great detail here about how exactly to use the analysis software, other than to say I tend to focus my attention on two areas: (1) speed-over-distance graphs of mph and g-forces, and (2) GG diagrams or friction circle diagrams.
With speed-over-distance graphs, which are those classic looking data acquisition "peaks and valleys" lines you'll see a few of in our cover story, you're seeing a visual representation of the data across a lap of the racetrack. Aim's software does an excellent job of identifying the corners and marking those for you along the top of these line graphs, making it easier to quickly assess in which corners Setup A or Car A was faster than Setup B or Car B. You can also gain some valuable insight into the driver's use of the brakes and how the braking system is performing by taking a close look at how steeply the speed line drops in key braking zones.
But to really see if the driver is using every bit of available grip out there, both in the corners and in the braking zones, the GG diagram (or XY plot) is an extremely useful tool. This type of data graph plots lateral (cornering) g's on the horizontal axis and longitudinal (braking and acceleration) g's on the vertical axis. This pattern of the data points is based on the so-called friction circle, a theoretical circle of maximum g-forces that a tire can develop, be it straight-line acceleration, straight-line threshold braking, on-the-limit cornering, or some combination of these. You can, for example, be braking and cornering (via a driving technique called trail braking) at the same time, just like you can also be cornering and accelerating at the same time. So data points on the GG diagram can be showing both lateral g's and longitudinal g's, generating a theoretical circle.
In reality, the data points on a GG diagram tend to result in a heart shape rather than a circle, since cars cannot generate nearly as much g-force while accelerating as they can while braking, nor can they generate as much braking g's as they can cornering g's. As you can see from the GG diagram here, where I've compared the two test cars from the cover story, the car represented by the orange data points is filling out the circle in the bottom right and left areas, meaning the driver is better able to trail brake into corners and accelerate earlier coming out of them. You also notice that the pointed bottom of the heart shape isn't very pointy, and that's because both cars were suffering from brake fade, so rather than achieving the expected 0.9 or so g's while braking, we were only seeing 0.7 to 0.8 g's.
You get the idea. Data acquired via a GPS lap timer like the Aim Solo can be a really powerful tool when you're ready to get serious about going fast. And the beauty of data like this is that it never lies. As you may have experienced at an HPDE event or driving school, in-car instructors can (depending on how experienced and skilled they are) sometimes give contradictory or confusing feedback, but the data you collect with a GPS lap timer has no ego and no predetermined ideas about how to go fast, and because it's recorded for review at a later date, it's much easier to spend some time analyzing it and really absorbing its meaning.