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Horsepower on the Fly with AEM’s AQ-1 Data Logger and Dyno-Shaft


Data logging use to be something limited to only the world of elite racers. Laptops, stashed on the passenger’s side of the car would record a bevy of information for racers, and crew to decipher. Data loggers were expensive, and often limited in their recording abilities by the laptop they were connected to, as well as compatibility with the sensors installed. Some of the early ones you really did seem to need a PhD to decipher the information as well.

AEM Electronic’s AQ-1 data logger however, offers racers and enthusiasts an affordable data logging system. The AQ-1 is compatible with a variety of OEM, aftermarket and AEM sensors. It can utilize the powerful AEMnet features, allowing compatible components to be daisy chained together. The software as well is straight forward, easy to setup and use.

The AQ-1 comes with the necessary harness for connecting it to a variety of sensors, it also includes a USB cable to connect it to a laptop for setup. All of the AQ-1's inputs are silk screened, which makes wiring easier. We connected the Dyno-Shaft to AEMnet and our Wideband Boost Pressure Failsafe gauge to supply information back to the AQ-1.

We’ve already installed an AEM Wideband and Boost Pressure Failsafe Gauge in Project Wild E Coyote. For this installation we’ll also be adding to our arsenal an AEM Dyno-shaft, hooking up our AQ-1, and taking a look at why this is such a powerful set of tuning and track day tools.

AQ-1 Installation

We installed the AQ-1 under the driver’s seat of Wild E Coyote. It is important to note that the AQ-1 must be mounted as outlined by AEM in order for its built in accelerometer to function correctly. Aside from our AEMnet connections, we simply had to wire in a power, ground, 12 volt ignition switched, and a switched ground. The system logs data on an SD card, which allows a user to log multiple runs and review the data at the end of the day, or after each pass on a laptop.

We mounted the AQ-1 under the driver's seat following the instructions for proper mounting and orientation.

We connected the following inputs to the AQ-1 from Wild E Coyote:

  • Wideband and Boost Failsafe Gauge
  • AEM Dyno-Shaft

We walked through the AQ-1 setup process. The AQ-1 software is simple and straightforward to configure. Much like setting up a new piece of hardware on your home computer, the AQ-1 auto detects devices and inputs connected to it. The proper calibrations must be set and inputs to be logged selected.

Left: The AQ-1 setup process is fairly straightforward. The system will auto-detect items that are connected to it. Right: Once the device has been detected it will show up on the AQ-1 setup screen.

The pressure sensor for boost is then calibrated for the correct readings by AQ-1.

Next the Wideband AFR sensor input is also calibrated to give the correct reading.

The last screen is an overview of which sensors are selected for logging, and also how the AQ-1 is triggered to start a new log. We set this to start logging when battery voltage is 13.5, this is basically anytime the car is started up, allowing us to log a drive to work, or a trip down the drag strip without having to remember to flip on the data logging switch. You can wire a ground switch to one of the digital inputs as a way to control the data logging

What is Dyno-Shaft?

The AEM Dyno-Shaft works by measuring the twist in the driveshaft before the rear differential. -Paul St. Clair

AEM’s Dyno-Shaft is a precision instrument for measuring your car’s output in drag racing, road course, autocross, and even day to day scenarios. The Dyno-Shaft is not a novelty gauge, or another accelerometer, it is a set of laboratory strain gauges that is installed in the car’s driveline.

The Dyno-Shaft installs in place of the driveshaft slip-yoke. There is then a pickup for the Dyno-Shaft that attaches to the transmission tail-shaft housing. This all connects back to the AQ-1 via a single AEMnet connection. There are no batteries in the system you can leave it on your car indefinitely.

How the Dyno-Shaft Works

The heart of the system is this slip yoke which replaces the one on the driveshaft and reads twist in the drivetrain. The sensor will attach over the transmission tailshaft where it will send the information back to our AQ-1 data logger.

The Dyno-Shaft relies on resistance, “It measures the twist in the driveshaft before the rear differential,” according to Paul St. Clair of AEM Electronics. The resistance against the driveshaft is from the tires. As the car is driven on the track or the street, the Dyno-Shaft is measuring how much power is being put through the tires to the surface effectively at any given point. A drop in power shown by the Dyno-Shaft will typically indicate one of two things, either tire spin, or a drop in engine performance.

Drag Racing

The data from the Dyno-Shaft is especially useful in racing applications. By having the Dyno-Shaft and AQ-1 onboard during a day at the drag strip, we can data log and effectively find out how much power from our car the track will hold, given current weather, track, and even car conditions.

When data is reviewed from a run, tire slip shows up via the Dyno-Shaft data as a drop in torque, this is because resistance at the tires has decreased as traction decreased. Racers or enthusiasts can then use that data to assess whether that decrease in traction was due to a track condition, or the car overpowering it’s tires. “There’s only resistance as long as the tires have grip, the torque will drop in your log, and you’ll see where your tires start slipping,” says St. Clair.

Left to Right: The Dyno-Shaft is installed by removing the driveshaft and replacing the slip yoke with the Dyno-Shaft slip yoke You will want to verify that the yoke has the minimum clearance needed to detect the driveshaft's rotation from the housing sensor. The sensor is installed on the transmission tailshaft housing. The driveshaft is then reinstalled, and the input connected to the AQ-1 AEMnet connection.

Tuning with Dyno-Shaft

By having the information that Dyno-Shaft provides, a car’s setup can be adjusted to maximize performance for a wide arrange of conditions. Torque is multiplied by the transmission gear ratios and differential in any car. The Dyno-Shaft can help determine exactly how much torque can be applied to the track by a car’s setup. For example If it’s determined via the data that the tires are spinning at 1,000 lb-ft of torque, then ideally race strategy could be adjusted to get the car to only apply 999 lb-ft of torque. If traction can be quantified as a number then the fastest way to get the car down the track is to apply the maximum amount of torque the track and tires will hold based on the data gathered. Changes that crews and racers might make include add or remove timing, change chassis adjustments, adjust the boost, nitrous, shift point, or launch or shift RPM. The Dyno-shaft can even detect traces of knock from the engine as it temporarily reduces power during a run.

Looking at the data from the AQ-1 we can see where Wild E. Coyote made peak HP of 570 at 6,600 rpm, with an air fuel ratio of 11.43 and 7 psi of boost. The bottom panel shows engine power, while the top shows our RPM, AFR and Boost.

Similar information is shown for peak torque, which is 451 ft-lbs at just over 5,200 rpm. The graph even shows how fat and flat our torque curve is, showing it ramp up significantly starting around 2,200 rpm and staying strong all the way through the run.

There’s only resistance as long as the tires have grip, the torque will drop in your log, and you’ll see where your tires start slipping. – Paul St. Clair

Dyno-Shaft users can also determine if a drop in elapsed time or MPH was a result of driver error, track conditions, or component failure. For example, let’s say ET starts dropping off over the course of a day at the track. The data can be analyzed to determine if the driver is making an error, if track conditions are degrading, or if there is a potential problem with the car. This could save valuable time in the pits making setup adjustments based on guesswork, and instead directing efforts towards resolving problems that will ultimately result in a win for the weekend.

Torque Converter Tuning

Driveshaft speed sensors are nothing new in the world of data logging. The Dyno-Shaft has one built into it as well, eliminating the need for one more additional sensor. Where the Dyno-Shaft differs is that it can also show the torque converter slip for each gear by comparing engine rpm, and driveshaft speed. By using the transmission gear ratios the torque converter slip rate can be calculated from this information. This can be exceptionally valuable in terms of looking at converter performance and converter health.

Further reviewing the data, Dyno-Shaft users can also see not only what RPM the converter stalls and locks at, but also at what torque it’s occuring at as well. This can give you valuable tuning information to provide your transmission or torque converter supplier, further allowing them to fine tune a custom torque converter for a car’s specific needs.

Road Course Tuning

Similar principles apply in road racing, and the Dyno-Shaft may even prove more valuable there when coupled with the AQ-1, and other AEM devices.

 Tuning Out Knock With Dyno-Shaft


One of the more interesting results we had with the Dyno-Shaft was the detection of a hole in our torque curve. After looking at our Data St. Clair pointed out that there was a hole in our torque curve occurring just shy of 3,200 rpm, and our air fuel ratio also took a dramatic turn there as well. We suspect the problem is timing related, possibly unheard spark knock occurring. Fixing this problem may improve the car’s performance, and in the long run could save wear on engine parts.

The AQ-1 features a built in accelerometer. After taking a few laps or post race it is possible to look at how much horsepower and how much g-forces the car was producing in various areas of the track. Just as in drag racing, setup changes can be made to adjust the car so that the maximum amount of power for the available grip is used throughout the track.

St. Clair also pointed out, “On a road course, in the straight away you’re basically on a dyno run,” as you shift into fourth gear, the car is essentially making a loaded dyno pull each time it passes through the straight away. This information too could be a critical indicator of overall engine health. An engine might potentially start the race making 500 hp, only to see that power drop as time goes by. Tracking the data with the Dyno-Shaft, and other tools on the AQ-1, this information could be compared to things like coolant and oil temperature, coolant temperature, oil pressure, and even environmental or weather conditions. Knowing that an engine needs attention before it leaves the racer out of the running is yet another valuable asset, potentially saving time and money.

Analyzing the Data

With the AQ-1 ready to go we strapped the car to the chassis dyno and for some comparison between our recorded data and the chassis dyno. We found that the Dyno-Shaft power numbers coincided with the chassis dyno numbers. What this tells us is the Dyno-Shaft is extremely precise, and a valuable tool that we can’t wait to use at the track to see if we can shave a little more ET off of Wild E’s passes, as well as maximize traction and detecting knock, so we don’t lose a round because of tire spin.

Our numbers from the Dynojet chassis dyno would seem to confirm the accuracy of the Dyno-Shaft when the two are compared.

The horsepower and torque data from our AQ-1 in a traditional dyno graph format.

With the Dyno-Shaft now installed in Wild E Coytote we can work on multiple aspects of our total vehicle tune to find the sweet spot for drag racing, or at the auto cross and road course. We’ve already found one potential problem with our tune which if left unchanged has the potential to lead to severe engine damage. Catching problems like this quickly makes the Dyno-Shaft more than pay for itself by saving wear and tear on much more expensive parts like the engine. At the track having a tool like the Dyno-Shaft means that whether you’re racing in the big leagues, or just a weekend bracket racer, you have one more piece of data in your arsenal to maximize your chances at coming away from the weekend with an event win.

Sources

AEM Electronics
Phone: (310) 484-2322


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