Dyno results are often shared and compared online, but it's important to understand that dyno data from different machines should not be directly compared using peak power or torque figures alone. There are many variables involved that can significantly influence the numbers shown on a dyno graph.
Why peak figures can't be compared accurately
Comparing peak horsepower or torque figures between different dynos is unreliable for several reasons:
-
Different correction factors
Dynos apply correction factors to account for environmental conditions such as temperature, humidity, and altitude. Different dyno brands — and even different software versions — can use different correction standards, which directly affects the final numbers displayed. -
Calibration differences
No two dynos are calibrated exactly the same. Small calibration differences between machines can result in noticeable variations in reported power and torque figures. -
Vehicle strapping and setup
The way a vehicle is strapped onto the dyno can vary depending on the operator. Strap tension, angle, and how much the vehicle is allowed to “climb” onto the rollers can all change how the dyno reads load and resistance. -
Dyno configuration and ramp rates
Dynos can be configured differently depending on ramp rates, load control, smoothing, and other parameters. These settings affect how quickly the engine is loaded and how power is recorded throughout the run, which can alter peak figures.
What can be compared reliably
While peak numbers between different dynos are unreliable, overall gains are much more meaningful.
If you compare:
- The before and after results on one dyno, and
- The before and after results on another dyno,
and then look at the difference between those results, the comparison is usually quite accurate. Evaluating the area under the curve — rather than a single peak number — provides a much better indication of real performance improvements.
This approach shows how much usable power and torque has been gained across the rev range, which is what the driver actually feels on the road.
How dyno figures can be unintentionally (or intentionally) inflated
Dyno figures can be influenced — sometimes significantly — by changes in setup between runs.
For example, if a vehicle is run on the dyno in stock form, removed to have modifications installed, and then placed back on the dyno, even small differences in setup can affect the results. Factors such as:
- Tyre pressure
- Strap tension
- Vehicle positioning
- How much the vehicle is allowed to load up on the rollers
can all change the readings.
Environmental conditions are another major factor. Changes in temperature, humidity, or barometric pressure will alter the correction factor applied by the dyno, which can lead to noticeably different figures even if the vehicle itself hasn't changed.
What a dyno is actually for
A dyno is best understood as a tuning and diagnostic tool, not a universal benchmarking device.
Its primary purpose is to:
- Measure changes made to the same vehicle
- Verify that tuning adjustments are working as intended
- Safely and repeatably apply load during the tuning process
Using dyno graphs to compare different vehicles, different shops, or different dyno brands rarely provides meaningful or fair results.
The takeaway
Dyno data is most valuable when used consistently on the same dyno, with the same setup, on the same vehicle. When interpreted this way, it is an extremely powerful tool for tuning, validation, and development — but peak numbers alone should never be used to compare results across different dynos.