AEM Dyno-Shaft: On-Vehicle Dynamometer System

AEM Dyno Shaft, drive shaft dyno, on vehicle dynamometer system,

AEM Releases the Dyno-Shaft On-Vehicle Dynamometer System


Have you ever made engine changes at the track and wished you had access to a dyno to see if they worked? Have you ever wondered where your racecar’s power went coming out of a turn, knowing there are too many variables to trace to root out the problem during competition? With AEM’s Dyno-Shaft on-vehicle dynamometer system you can finally stop trying to approximate real world test conditions and start testing in the real world!  AEM’s Dyno-Shaft on-vehicle dynamometer system eliminates this guesswork by providing real, accurate Horsepower and Torque numbers that are produced by measuring a vehicle’s Torque and RPM at the driveline, while you drive!

The Dyno-Shaft is a true on-vehicle dynamometer system that delivers Horsepower and Torque numbers as accurately as the most respected dynamometers, with the major advantage being that it measures power while the vehicle is under operation in real-world conditions. It is not an accelerometer-based system, so it will not skew readings due to uphill or downhill transitions, crosswinds, vehicle aerodynamics, wheel spin, vehicle weight or the myriad other factors that can affect the accuracy of GPS/accelerometer-based units. Instead, it measures a vehicle’s actual transmitted Torque and speed at the driveshaft, allowing it to record and output REAL Horsepower and Torque numbers.

Eliminate Guesswork—Know for sure if slower times are due to a loss of power, vehicle set up or driver error.

Engine tuning – Stop trying to approximate real world test conditions and start testing in the real world! Finally you can test with actual intake air conditions, actual vehicle loading and the hundred other things that make a real vehicle behave very different than it does when on a dyno.

Chassis Set Up—Know when the tires will break loose. Ideal for optimizing drag launches and determining the longitudinal forces your tires can handle in road racing.
Torque Converter and Clutch development – Finally know what your Torque converter or clutch is doing while you are making a pass!

Dyno It All—The Dyno-Shaft accurately reads in all conditions including steady state, uphill or downhill, even while coasting down!

Great for 2WD Diesel Rigs—Know exactly how much power it takes to get up a 5% grade with a 20 MPH headwind and five tons hanging off the 5th wheel. The Dyno-Shaft can also be used for engine/exhaust brake performance during coast down.


AEM Dyno Shaft, drive shaft dyno, on vehicle dynamometer system,

AEM uses a set of laboratory-grade strain gauges inside of a supplied slip yoke to measure Torque at the driveshaft. Essentially, the Dyno-Shaft slip yoke becomes the sensor for measuring driveshaft Torque. This is combined with a driveshaft speed sensor to precisely measure the rotational speed of the yoke to determine RPM. The combination of real Torque and RPM readings allows the Dyno-Shaft to output Torque and Horsepower numbers as accurately as any dynamometer but in a more useful setting, and eliminates all of the inaccuracies associated with accelerometer based systems.

The data broadcast device (Controller) for the Dyno-Shaft yoke is non-contact, does not have slip rings, does not require batteries and is maintenance free. This Controller installs over the transmission tail shaft housing and allows information from the Dyno-Shaft to be transmitted via AEMnet (AEM’s CAN-bus communications network) to a data logger, AEM or other programmable engine management system, or custom dashboard via a single connection.


AEMnet is a high-speed communications system based on CAN-bus 2.0 architecture. AEMnet allows you to daisy chain AEMnet-equipped products together using a single cable to connect each device, reducing the wiring time required to add devices. CAN bus (Controller Area Network) is a single- or dual-wire serial bus protocol that connects systems and sensors and allows them to communicate. Please visit the AEMnet page on for more information.


AEM Dyno Shaft, drive shaft dyno, on vehicle dynamometer system,
Sportsman Slip Yoke


The Sportsman slip yoke is manufactured from ductile cast iron and the splines are manufactured from a broaching process that produces industry-leading mating fit parts. Each Sportsman slip yoke is temperature compensated and individually calibrated for load through a multi-point process. The Dyno-Shaft Sportsman Series is designed for competitive amateur racers and serious performance enthusiasts whose applications can utilize a cast iron slip yoke. Professional racers with higher stress applications that require a Chrome Moly machined slip yoke will need to purchase our Dyno-Shaft Pro Series System.

The Pro Series slip yoke for the Dyno-Shaft is manufactured from Chrome Moly and CNC machined to ensure balance and concentricity. They are heat treated to ensure optimum tensile strength. The Pro Series yoke is case hardened for applications with roller bearing extension housings. The Pro version undergoes a Laboratory-Grade calibration process and receives a unique polynomial curve fit to ensure the most accurate readings across the entire Torque band. These processes ensure product reliability and accurate readings race after race regardless of operating conditions. The Dyno-Shaft Pro Series System is designed for professional racers with high stress applications that require a machined Chrome Moly slip yoke.

Installation is relatively straightforward. Users install the Controller and integrated driveshaft speed sensor externally onto the transmission tail shaft housing, then replace the factory slip yoke from their transmission with the Dyno-Shaft slip yoke.

At its core, the Dyno-Shaft is a sensor that measures Torque and RPM and uses this data to output a vehicle’s Horsepower and Torque in real time. You will need a ‘host device’ to record, view and output data from the Dyno-Shaft. The following devices are capable of reading and logging data from the Dyno-Shaft via AEMnet:


AEM AQ-1 Data Logger

  • The AQ-1 is the ideal host device solution for the Dyno-Shaft as it provides the broadest set of features and functionality, including:
  • The ability to create dyno charts which can be saved, printed or shared electronically.
  • The AQ-1 is a full featured data logger, so continuous power data can be recorded and replayed along with a wide variety of other vehicle information.  Please visit the AQ-1 Data Logger page on for more information.

AEM Series 2 Programmable EMS
Like the AQ-1, the Series 2 EMS allows logging of continuous power data which can be replayed along with a wide variety of vehicle information, and has the ability to create dyno charts which can be saved, printed or shared electronically.

Certain CAN-enabled devices from other manufacturers are configured to read Dyno-Shaft data.  If you do not have one of the AEM devices listed above you will need one of the devices listed below, and will need to confirm that it can read the data from the Dyno-Shaft by contacting AEM Tech Support or Sales Department at (310) 484-2322, or verifying through your authorized AEM parts supplier:

  • CAN-enabled Data Logger
  • CAN-enabled Programmable Engine Management System
  • CAN-enabled Racing Dash

AEM’s Dyno-Shaft Gauge is a display gauge/dyno interface with basic logging capability that will allow you to view Horsepower and Torque data in real time via information transmitted from the Dyno-Shaft through the AEMnet CAN bus network. The Dyno-Shaft Gauge will feature two buttons on the faceplate for viewing peak Horsepower and Torque values, resetting peak power values, replaying dyno pulls and zeroing the Dyno-Shaft sensor.

A full-color OLED display will reside inside the center of the unit’s 52mm (2 – 1/16”) housing to provide immediate reference to power or Torque (user-selected). The gauge’s sweeping LEDs will be user configurable to display power, Torque, or boost. Illumination adjustments will allow for single value LED illumination or illumination of all LEDs up to the current value. The Dyno-Shaft Gauge will also include interchangeable faceplates and bezels to customize its appearance. Anticipated release is Q1 of 2012.

AEM Dyno Shaft, drive shaft dyno, on vehicle dynamometer system,


  • Measures Torque and RPM at the driveline to deliver real Horsepower and Torque numbers
  • Does not skew readings like accelerometer-based units
  • Eliminates guesswork when troubleshooting or making changes at the track
  • Laboratory-grade strain gauge requires no slip rings or batteries and is maintenance free
  • Each unit is individually calibrated at AEM
  • Create dyno charts to save, print or share electronically with AEM AQ-1 Data Logger, Dyno-Shaft Power Gauge ( gauge coming soon), and Series 2 EMS
  • Can be used with some CAN-enabled engine management systems, data loggers and displays (contact AEM Technical Support or Sales Department at (310) 484-2322, or contact your direct vendor to confirm whether your CAN-enabled device can read the Dyno-Shaft datastream)


Stay tuned for a full review of the AEM Dyno Shaft on Project V8-RX7


Please visit or call (310) 484-2322 for more information or to find an Authorized AEM Electronics dealer or Factory-Trained tuner.  You also may be interested in our Tech section.

Leave a Reply

Your email address will not be published. Required fields are marked *