Drag Racing Data Analysis and Acquisition: Logging Concepts and Techniques

AEM Performance Electronics provides an in-depth dive into data analysis and acquisition through a discussion with multiple drag racers.

Written by Ainsley Jacobs, courtesy of AEM Performance Electronics.

Only a few short years ago, drag racing seemed significantly simpler. Weather stations and chassis specialists could get you going in the right direction rather quickly based on only a few inputs, and decisions about how much power to add (or pull) were made through visceral tools like touch and feel – bare hands on tires or shoes on the track. 

Although there are still seasoned bracket racers who rely heavily on the old school tricks of the trade, more racers are embracing electronic innovation and reaping the rewards for doing so. Logbooks are being supplemented by detailed data logs to gain a competitive advantage, go rounds and land a coveted spot in the winner’s circle.

Learning to use a data logger, though, is only a part of the overarching challenge. It means nothing if you don’t know what to do with the data once you’ve got it. For aspiring data analysts and even experienced acquisitionists, the sheer amount of data that can be collected can overwhelming. What exactly should be collected at the basic level? What are more advanced methods of data acquisition and analysis that professionals use, and how can you apply those to your own program to run quicker and prevent problems along the way? To answer some of these questions we contacted AEM, who suggested we talk with some racers who have upped their game over the past few seasons by implementing data analysis into their racing program. 

In full disclosure, most of the racers and crew chiefs we spoke with have a lot of experience with turbocharged drag cars, so many of the examples we provide will be skewed toward these types of vehicles. But, our hope is that anyone reading this will take away something that they can use. The subject of data analysis and acquisition is vast and although this is not intended to be a comprehensive, definitive “how to” guide, it will help shed light into some common areas of the black art of data analysis.

The Basics

To start, it’s recommended to set up standard channels such as air/fuel ratio and boost or vacuum along with other necessities such as fuel pressure, engine oil pressure, engine oil temperature, water/coolant temperature, timing, and more. These channels give good insights into the engine’s overall health and operating state. By themselves, they can warn you of an issue, but with some experience when you see two or more of these that are simultaneously not where they should be during a pass, they can lead you to the likely culprit much more quickly.

Eric Holliday, the talented tuner at JPC Racing who is responsible for many of the quickest and fastest NMRA Street Outlaw, Renegade, and Coyote Modified cars, has extensive experience working with smaller-displacement turbocharged combinations – be it Modular motors, Coyote engines, or pushrod powerplants – but knows the basics apply to all engine types regardless of size or origin.

“Get situated, and when you’ve got a car that will start and run, the next step is to move into specific sensors to give you the data you need about whatever you’re trying to control, be it shock sensors or transmission things,” added Holliday, “If you’re new to a logging system or aftermarket ECU, you’ll want to record things like the throttle position and MAP sensor.”

Once you’ve got a couple laps under your belt and have a solid A-to-B tune up in the engine computer, it’s fairly straightforward to overlay data from runs on top of one another and see what areas can be improved upon. If the car is down on boost because of weather conditions, or making too much because of good air, you’ll have your files to compare and can get an “off the trailer” type tune up ready to get down the track in almost any situation. 

“Temperatures and pressures are absolutely key,” reiterated Justin Jordan, proprietor of late model domestic drag racing-specialty shop Jordan Performance and Racing. “If you know your engine is staying cool and healthy, that’s half the battle. If you measure air coming in, its temperature, and fuel going in, you’ve got most of what the engine needs to run already covered.”

Monitoring coolant pressure allows you to see when the pressures begin to creep up, and make an educated decision on how much longer you can safely push it – or if an engine refresh is needed. Basically, if the coolant pressure logs look like your boost pressure logs, that’s not a good sign!

Craig Watson, owner of a notorious 8-second ’73 Chevy Nova and nitrous oxide guru, has an expert handle on what to log and how to interpret the acquired data as well.

“After a typical run, the first thing we look at when we pull up the data is the crankcase vacuum to make sure the tune-up was happy and we don’t possibly have any hurt cylinders,” explained Watson, who also checks the oil pressure during the run to make sure it was normal and needs to know if anything went awry to maximize his chances of making a repair before the next round. He documents the nitrous pressure, fuel pressure, shift RPM, and RPM at the finish line in his log book, along with the timeslip information and any additional relevant notes. “I’ve already, of course, documented the weather and the setup of the car before the run in the log book.”

Fuel pressure feedback is incredibly useful, regardless of power adder. In Watson’s world, nitrous is the name of the game and the data he receives from his fuel pressure sensors for both the carburetor and nitrous systems keep him informed if the fuel pump is getting worn and losing flow during a run while the AEM X-series wideband oxygen sensors give him important tune-up data early- and mid-run that he can’t always see on the plugs themselves.

Individual Cylinder Monitoring and Boost Channels

Most moderate or serious drag cars also have exhaust gas temperature (EGT) sensors dedicated to each cylinder, often paired with their own wideband oxygen sensors as well. After each run, plugs are pulled and compared to what the data is reporting. “The more information you have, the better the decisions you can make,” asserted Holliday, who built a successful career on making winning decisions. Once you collect the data, you can start putting two and two together to figure out what changes effect what. 

Wes Choate, owner of the Missouri-based tuning and EFI conversion specialist shop Sho-Me Speed, regularly manages some of the baddest LS-powered no prep cars in the Southeast and is no stranger to the power of power management and how to use certain sensors to his advantage. He also does a lot of tuning for the off-road industry, including Ultra4s for King of the Hammers.

Choate often utilizes the AEM AQ-1 data logger along with eight wideband O2 sensors and the AEM Infinity ECU to help get cars in his care up to speed. “The 8-channel wideband is priceless to see cylinder-to-cylinder distribution and see what one is doing versus another,” he outlined of how he helps keep on eye on head flow and dials in the fuel and timing for each individual cylinder.

Putting sensors on a car allows you to see what it does before, during, and after a run. Owners of turbocharged cars, for example, often monitor the wastegate dome pressure – the amount of pressure that’s being put on the wastegate to ensure the target boost is reached and maintained. “If you’re trying to add more pressure to the wastegate to make more boost and it’s not doing it, you can look at the data to see why and adjust accordingly,” explained Holliday, “maybe the turbo won’t make more boost faster or you need to leave on more boost – rule out why it’s not doing what you want or why it’s doing something weird and unexplained.”

Carey Bales, king of the four-cylinder turbocharged import scene and owner of Race Tactics, who is now expanding his horizons to include the Coyote platform, always collects the basics but typically adds boost lambda to his portfolio. “With the wastegate position sensors and backpressure, we can also see how efficient the turbo is and that lets us know what type of boost control we should command through the ECU,” he elaborated.

When backpressure increases rapidly disproportionally from the manifold pressure, it’s a strong sign that the turbo is running out of air. “If the RPM trace becomes erratic at, say, 58 PSI of back pressure, it’s safe to assume we are starting to float valves,” Holliday stated, who typically allows for more back pressure early on in a run and less up top as the valvetrain becomes less stable at higher RPMs. “A lot of time in a limited turbo application, you will be able to run more back pressure in the early RPMs and less up top since the valve train becomes less stable at high RPM. You can use this information to build a boost curve based on RPM and time to keep the back pressure in check. More often than not with a limited turbo application, you will have to build in a boost dump out the back of the track to keep this under control and the backpressure sensor will allow you to really tune that point in.”

Driveshaft Speed is Critical

An important intermediate-level component to monitor in drag racing is the driveshaft speed, so you can easily see whether your car is going faster or slower at certain incremental points in the track. “The driveshaft sensor is key to measuring clutch slip or converter slip, and tire spin,” Holliday continued, who understands the importance of measuring the metric on an automatic transmission-equipped car.

Let’s say you have to abort a pass but you get to half-track before lifting. Up to that point, you have no idea whether you were faster or slower than you best full pass, and your time slip isn’t really going to give you the answer. With a driveshaft speed sensor, it’s really easy to get the answer by overlaying data from a good pass that you know the incremental times for with the data from the aborted pass and comparing them to see if the driveshaft RPM during the aborted run was higher or lower than the known good run.  This overlay might reveal that you outran your last pass by 250 RPM and started to wheelie – now you have hard data now that tells you something meaningful, and from here you can either make a power management or chassis adjustment.

Auto Trans – Add Torque Converter Line Cooler Pressure

Monitoring an automatic transmission’s cooler line pressure can also give insight into what’s going on throughout the run, too, and what the converter is doing. “Your converter shop is going to want that information, too, so you need to track it.”

Depending on conditions, Jordan makes adjustments to the converter and uses line pressure to help guide his choices. On loose tracks that are greasy in the heat of the day and hard to get down, he’ll opt to take some of the bite out of the converter by loosening it up by dumping some pressure. “I have a channel that starts to count when I let go of the trans brake,” he detailed of the setup. “I can look at the log and, say I normally go a 1.19-second 60-foot, I can look at the first 1.19-seconds and see what the car is doing. If it spins, I take power out. Or if not, add power because the track can handle it.”

Watson considers data a crucial tool for evaluating changes with his torque converter. After making an adjustment at an NMCA race in Norwalk, Ohio, he was able to see that the flash stall speed, RPM drop at the shift, and top end slippage, all pointed to his converter being a little tight and he was able to throw some more power at it.

Manual Trans – Add Clutch Speed

Bales monitors similar channels because “with clutch speed and driveshaft speed, we can calculate clutch slip and other important pieces of information.” With stick-shift, clutch-equipped cars, it’s critical to know when to have the clutch lock up and many different determining factors go into play – the first gear change, weight of the levers put on the arms, how tight the clutch is initially, etc.

“Once we have a good baseline, we look at the separation of engine RPM and driveshaft and it lets us know how much the clutch is slipping,” Bales said of what he looks for when building his tunes. On the launch, how quickly the clutch does or does not slip is a good measure of whether or not the car spun the tires. “The engine, clutch, and driveshaft RPMs all dictate the slip and how aggressive the clutch is in the chassis, and that’s the most important part for our program.”

Using AFR to Optimize Shift Points

Another interesting area of data acquisition and analysis is that of fuel management, and Jordan has plenty of wisdom to share on the subject. For starters, he recommends taking a look at where the computer is commanding the shift versus where it’s actually shifting, based on rpm drops, and adjusting shift points accordingly. The reason being that, if you have had your car on a dyno and know where it makes peak power and peak torque, you can adjust the shift points and use data logging to make sure you’re capitalizing on potential power gains and not leaving anything on the table.

“The new Mustangs are 10-speed automatic and shift so fast, so the shift drop is minimal and it basically sits in the powerband the whole time,” he detailed of Ford’s 10R80 transmissions. “If I know a car makes 450 horsepower at 7,000 RPM and I average 6,800 RPM on a run, that’s pretty good.”

As Jordan runs a twin turbo configuration on his ’14 Mustang, he keeps an O2 sensor on each bank to make sure fuel is going where it’s supposed to and when. “Now, Camaros and Mustangs and Corvettes all come with wideband O2 sensors from the factory and run a closed feedback loop system so it’s giving real-time computer feedback based on target fueling,” he noted of the change from non-wideband equipped cars back in the day when an aftermarket accessory was a must for any performance-minded person. “My job as a tuner is to make sure my fuel trims [the adjustment the engine computer makes to the fuel mixture to maintain a balanced air/fuel ratio, also referred to as injector feedback] stay within plus or minus 5%.”

To do so, Jordan adjusts his tunes and fuel maps all according to data that he’s logged and analyzed. “If I’m commanding .8 lambda (80%), then I’ve got too much fuel in the map while 1.0 is zero correction and ideal,” shared the tuner. If he does good work on the backend giving the computer what it needs, the less work it needs to do on the track to adjust fuel on the fly. “What can be measured can be managed – and I do that with a data logger, either my AEM Infinity or CD-7 logger dash. If you aren’t logging, it’s more or less a waste of your time.”

Shock Pots and G-Meters

As more advanced data acquisition and analysis techniques are implemented, many racers add G-meters and shock sensors to their setups. When traction becomes limited, power management takes center stage.

Running a small motor in a full chassis car with big tires makes it hard to overpower the traction, so Bales doesn’t often worry about that with his own program, but he knows the importance of using the engine computer to make real time changes to pull power during a run based on chassis feedback. “With a high-horsepower small tire car where they’re traction- or wheelie-limited, suspension travel sensors allow you to pull timing once a certain point is reached,” he mentioned. “Plus, thanks to chassis monitoring sensors, we’ve been able to diagnose shock issues that were causing problems that might have taken a long time to figure out otherwise.”

Jordan uses his shock travel sensors to give feedback on when, where, and how much his Mustang wheelies. “I look at the data from the shock sensors and throttle position (if I pedaled it) to show me where in the run it wheelied and determine how to fix it, either by power management or adding weight to the nose,” he disclosed.

Choate recommends working to keep the G-meter curve as high as possible, for as long as possible, since it’s a reference for acceleration and intelligent interpretation shows how much power is kept for what duration of time. As most races are won in the first 60- to 100-feet, whether it’s traditional class racing or no prep, often no amount of top-end charge can catch a guy who left on you at the tree.

“I use the AEM Infinity to monitor my shocks and see how fast they’re topping out, rebounding, or compressing,” noted Choate. When a track surface has a bump in it, he’ll look at the compression in the data and either soften timing or pull a shift down to help the car get through that bump smoother next time. “The shock sensors become really important for that sort of thing and allows me to layover logs from various runs to see where we lost RPM or driveshaft speed, too.” In no prep racing, tuners usually bring the power in slower and differently than on a prepped track, so having an abundance of data handy helps keep the keyboard jockeys on point with their power management.

Putting all the inputs together, though, is where the real magic happens and the value of data analysis becomes more readily apparent. After reviewing the basic data feedback, Watson evaluates his runs based on driveshaft RPM, rear shock sensor, G-meter, and engine timing, and compares it all to see what happened via the slow-motion video his team recorded. On a typical race day, he asks the following questions:

• Did we have enough wheel speed at the hit or did we stick the tire?
• Did the wheel speed cause tire shake or did we over speed it?
• How does that driveshaft RPM correlate to the power application and suspension movement?
• Does the longitudinal acceleration on the G-meter stay high and smooth or did we leave ET on the table?
• How does the G-meter react after the shift – did we maintain acceleration and therefore shift at the proper RPM?

Using Data to Employ Failsafes with Standalone ECUs

An often-overlooked benefit in the data acquisition department is that of basic diagnostics and simple troubleshooting. Sometimes going fast isn’t the only goal, as not going broke can be equally as important. It’s never any fun grenading an engine (or a bank account), and proper data acquisition and analysis habits can prevent potential problems before they become catastrophes.

Things such as cam and crank signals, cam timing, and crank errors can all be logged and, in case of a problem, can be gone through to pinpoint where the issue occurred. Sometimes it’s as simple as a dirty sensor and a quick and easy solution can be found. It’s a no-brainer to enable the functionality if the ECU has the features.

Oil pressure and fuel pressure are critical to not blowing anything up. If either pressure is dropping and nothing is being done to compensate, it can cause big problems. “AEM specifically has a bunch of different protection functions and alarms in place,” shared Holliday, who regularly sets rev limiters based on cylinder head temperatures. “It makes the driver pull his foot out and maybe look at the dash and realize somethings wrong.” If oil pressure suddenly drops below a preset level, the engine can be programmed to shut down.

Similarly, if air/fuel ratios wind up out of whack, adjustments and accommodations can be made there as well as most systems are incredibly configurable. For example, if you don’t want to run leaner than 12:5 but are concerned about momentarily seeing that during a gear change, you simply set a time delay strategy.

A failsafe doesn’t have to mean a complete shut down or stop, though, as Bales explains. It’s possible to encounter a fuel pressure safety parameter that’s been put in place and still come out ahead. “It’s not necessarily always good – or needed – to shut the motor off in competition. We’ve had situations where the fuel pressure comes down a little and the ECU compensates so we can finish the run and still get the win,” he said. Sometimes, there’s more strategy behind just hitting a threshold and turning things off. “AEM’s systems are super-fast with data speeds and more intelligent with how they handle those types of things, and in the case of a points championship, it can be a really big deal!”

Overboost protection can also be great insurance for when you’re first starting to dial in your car; self-imposed rev limiters set at specific psi ratings ensure the engine doesn’t see a sudden spike in pressures.

Monitoring water/coolant pressure can also help prevent expensive engine annihilations, too, as it’s a good indicator of head gasket health. As you learn with your individual engine combination what is a normal water pressure number, anything north of that could be a symptom or sign of combustion getting into the cooling system and a head gasket on its way out. “We’ve been able to save a lot of failures – although we had failures to learn the parameters,” laughed Bales, “but now knowing them and setting failsafes and paying attention keeps the failures from happening again.”

Jordan has also “been there, done that” when it comes to keeping a careful eye on coolant pressure for the same reasons. In 2016 while racing in Bowling Green, Kentucky, he had a head gasket let go and torched the passenger-side cylinder head in his “NighTTmare” Mustang and all the water that was in the engine suddenly became pressurized.

“It basically exploded, the radiator blew in half, end tanks popped off, and 2.5 gallons of water dumped under my car at the 1,000-foot mark,” he recalled of his sideways slide through the traps at 175+ mph on what was, fortunately, a solo pass. “Now I have an aluminum radiator and AN fittings and I put a coolant pressure sensor in so I can look over at any time and know how healthy the engine is and if the heads are staying down nice and tight.”

Jordan’s story is just one of countless others who have been “saved” by data acquisition, and Tony Hobson has his own as well. Hobson, who trusts Holliday to do his tuning, is a familiar face in the fiercely competitive NMRA Street Outlaw category and regularly runs his turbocharged engine on the ragged edge.

“I lost oil pressure at one race, but had a safety feature in the AEM Infinity computer that ripped out all the timing and basically killed the motor before it ended up hurting itself,” remembered Hobson of how valuable data protected his valuable assets. Fortunately for him, it was a false alarm triggered by a faulty sensor, but the computer didn’t know that and acted accordingly in the unexpected fire drill. “All my wideband O2 sensors have built-in warnings, too, so if it goes too lean if I lose a fuel pump or something, it will try to save the motor. It’s like having an insurance policy! It might cost you the race but it can save you tons of dollars overall.”

For enthusiasts who are learning how to tune, having the protection features is a big deal. “So, if you don’t quite know what to do, you can put a safety setting in place in case you get a mistake,” agreed Choate.

Quantifying Product Development

Data acquisition and analysis is also incredibly useful in developing products for racing. When JC Beattie of ATI Performance Products is working on a new item, he uses data to refine and perfect it.

Manufacturing in-house using as many American-made materials as possible, ATI Performance is equipped with a hub dyno, engine dyno, torque converter dyno, two transmission dynos, and more. Three racecars that run anywhere from 6.70- to 9.70-second elapsed times are also considered “real world dynos,” and Beattie has everything wired with AEM equipment. “I rely on the AEM’s feedback for every transmission we build when we’re dyno testing, and we watch the data through the dash as well while also recording it. Collecting and analyzing the data significantly helps us optimize our products.”

Beattie is also a racer himself, and – of course – his cars are all sporting AEM sensors, dashes, and engine management systems. “With blower cars, having a plethora of wideband sensors really makes a big difference since air distribution is a mess and the widebands make cleaning it up a piece of cake after viewing the data logs or looking at the incoming data stream in real time,” he continued.

Visualizing the Data

In addition to having a configurable engine management system/computer, it’s also extremely helpful to have a way to quickly and easily access the data that’s being collected because all the data acquisition in the world means nothing if you don’t have the proper tools to help analyze it effectively.

AEM’s CD-7 digital logging dash, for example, accepts channels from CAN bus connections and is also compatible with third-party componentry. “For people who are new and still learning their routine, AEM’s dash is key because it’s configurable to prevent problems and set reminders, so you know where your numbers need to be and can easily see where the car is at,” noted Holliday. “As a racer, it’s phenomenally easy to use and I love the built-in features. It’s an awesome system with endless possibilities to help us improve the car, the transmission, and everything else,” Hobson agreed.

Watson uses his CD-7 digital logging dash to show custom layouts on each screen. For him, screen one shows driver Jeremy Lyons only the facts and figures he needs to see when he’s strapped in and making a run. Screen two, however, is for warm-ups and has additional information on temperatures, O2 sensor read outs, and driveshaft RPM data. Screen three is smartly set to display sponsor logos and draws attention while the car is in the pits and the staging lanes, while screen four has as many channels as he could fit and is used primarily for diagnostics.

The CD-7 dash makes the post-race data analysis process a convenient and easily repeatable task for Watson, who relies heavily on his dash to display pertinent details and appreciates the device’s digital prowess and flexibility. “Another great feature of the CD-series dashes is the ability to import data from the MSD Power Grid ignition controller,” Watson continued. “We no longer have to look at two separate data logs to see all the data – it’s all right there in AEMdata [data analysis software] where we can easily see the big picture.”

If you aren’t comfortable with tuning or doing data analysis yourself, or are worried about not always having your tuner with them at the track, AEM’s Infinity is also able to be tuned remotely. “We just log in and tune someone’s software with TeamViewer software or something,” said Choate, who can quickly see what’s going on in real-time and help his customers anywhere in the world all from the convenience of his shop. “AEM’s price point really does deliver great value. Sure, isn’t the cheapest, but with components like this, you don’t want to cheap out.”

“AEM’s products integrate perfectly with other AEM parts, of course, but they also play well with others and they have dash layouts and CAN templates that are plug-and-play for the beginner but also customizable for advanced users,” confirmed Bales, who appreciates the flexibility of the software.

In AEM’s Infinity engine management system, too, you have the ability to look at your tune file and your data log all in the same screen instead of having to switch back and forth. This significantly reduces wasted time, which can make or break a race when there are only moments to spare between rounds. 

“With InfinityTuner I can upload everything into one screen and it’s a huge time saver at the track,” shared Holliday. “Whatever you want to do, if you can think of it, you can do it with the Infinity – but it can’t order you tacos on Amazon… yet.”

The Takeaway

Taking the time to sort through a set up and implement thoughtful data acquisition channels can yield big dividends later on down the road. By being consistent in your data endeavors, maintaining a repository that’s organized intelligently by track, date, time, pass, etc., and keeping a physical log book can save time, save parts, save money, and translate to success.

Organization and interpretation are equally important, and it can be easy to get wrapped up in too much data, but starting slow and taking the time to fully analyze, interpret, and understand the acquired information will ultimately help you make momentous moves in the long run.

Continuous learning is the name of the game in data analysis, and always seeking to understand the what, why and how will help improve performance of the car and the skill of its tuner alike.

And, when in doubt, always consult an expert, work with your tuner, or contact your data acquisition manufacturer for assistance.

DISCLAIMER: THIS ARTICLE IS NOT TO SERVE AS A DEFINITIVE GUIDE OR HOW-TO BUT RATHER A REFERENCE MATERIAL OF CONCEPTS AND ANECDOTAL TECHNIQUES ONLY.

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