Every serious HO slot car racer knows that gut feel only gets you so far. If you want to build the fastest car on race day, you need data — and that's exactly what an HO Dyno delivers.
What Is an HO Dyno?
An HO Dyno (dynamometer) measures the actual power output at the rear wheels of your slot car. Unlike a simple RPM meter, a dyno measures real-world performance — accounting for motor output, drivetrain friction, traction magnets, and everything else that affects how fast your car actually goes on track.
The WER HO Dyno displays a 4-digit "dyno number" representing wheel power output, plus motor amp draw and voltage input — giving you a complete picture of your car's performance.
How the Dyno Works
Power is supplied to the copper rails on the purple roller platform, just like a slot car track. When the car runs on the platform, the rear tires drive the clear roller assembly. The roller is connected to a small internal motor that generates electrical output used by the dyno circuitry. Steel screws embedded in the platform help mimic the magnetic pull-down effect of track rails — an important detail that improves consistency for inline magnet cars.
Understanding the Dyno Number
The Dyno Number is a comparative tuning measurement — higher numbers generally indicate improved power delivery, but readings are intended for comparison and tuning purposes only. Dynos are not calibrated to an industry standard, so readings may vary slightly between units. The dyno is most valuable as a tuning and comparison tool, not as an absolute performance number. Always compare readings on the same dyno unit.
Why Use a Dyno Instead of Just Running Laps?
Lap times tell you the result. A dyno tells you why. With an HO Dyno you can isolate variables — swap an armature, take a dyno reading, swap it back, take another reading — and know in seconds which one makes more power, without ever putting the car on track.
What Can You Test?
- Armature comparisons
- Effect of traction magnet strength and position
- Chassis friction and drivetrain efficiency
- Motor break-in progress
- Before/after tuning changes
How to Use the WER HO Dyno
- Connect the included AC power supply OR use the installed internal 9V batteries
- Turn the dyno on by setting the power switch to AC or DC
- Place the rear tires of the car on the roller platform — guide pin must be installed (guide flag cars won't fit)
- Apply track voltage to your car and note the Dyno Number, Motor Amp Draw, and Input Voltage
- Make your tuning change and repeat
- Compare numbers — higher is faster. Record your results in a tuning log.
Pro tip: For best consistency, test at the same voltage you expect to race at.
AC vs. Battery Power — Which Should You Use?
AC Power (Recommended for tuning sessions): The included AC adapter plugs into a standard 120V outlet and provides stable, repeatable voltage — essential for accurate record keeping and back-to-back comparisons.
DC Battery Power (Great for race day): Two internal 9V batteries deliver approximately 18 volts, making the dyno fully portable when a power outlet isn't available. Keep in mind that battery voltage is not regulated and will gradually decrease as batteries discharge, which can affect reading consistency over a long session.
Tips for Consistent Results
- Always test at the same voltage setting per car class requirements
- Clean rear tires before testing — keep them dry and free from oil
- Allow motors to cool between runs
- Make only one tuning change at a time
- Record Input Voltage, Dyno Number, and Motor Amp Draw for every run
- Consider tire compound differences when comparing changes
- Compare readings only on the same dyno unit
Understanding Motor Amp Draw
Monitoring Motor Amp Draw alongside the Dyno Number can help identify efficient setups. Changes in amp draw may indicate differences in gearing, friction, tire condition, or motor health — giving you another data point to tune from.
Magnet Cars vs. Non-Magnet Cars
The WER HO Dyno is specifically designed to allow magnet cars to pull down on the roller platform, simulating real on-track downforce. Steel screws embedded in the platform replicate the magnetic pull of track rails. This is a critical feature missing from other dyno units and results in more accurate, repeatable measurements for inline magnet cars like T-Jets, Magnatraction, and Fray race cars.
Ready to Start Tuning?
The WER HO Dyno is compact enough for your home workbench (3.5" x 4.5" x 1.5") and portable enough for race day. No more guessing — just data.
0 comments