s200 - G Sensor


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Hondata, Inc.
2840 Columbia St
Torrance, CA 90503

s200 G Sensor

The Hondata G Sensor manual is available online.

What is the G Sensor?

The Hondata G Sensor is a module containing a two axis accelerometer which plugs into the s200 Interface Box. It allows you to datalog lateral and longitudinal acceleration simultaneously.

What do I need?

To use the G Sensor you need:


Price Description
Discontinued G Sensor module for s200

How accurate is the G Sensor?

The base accuracy of the accelerometer used in the G Sensor is 5 mG, or 0.005 G. For comparison typical acceleration is 0.25 - 0.50 G in second gear, braking and cornering generate 0.80 - 1.20 G. Vibration and mechanical isolation of the sensor from the chassis has an influence on accuracy, but this is in part offset by software smoothing.  Under typical conditions it appears that the G Sensor is accurate to 0.01 G.

How do I use the G Sensor?

The G Sensor allows you to datalog acceleration, cornering and braking forces simultaneously while the car is on the move.  Below is an image of the real time G Force display, showing the traction circle and the G Force as a vehicle brakes then corners.

The acceleration information can be used in conjunction with other datalogging sensor information for analysis. The image below is from the same recording as above, showing the manifold pressure as well as the lateral and longitudinal acceleration.

Since vehicle acceleration is directly related to engine output, given the vehicle mass and gearing it is possible to calculate the engine output to the wheels by recording an acceleration run.  Below is a sample dyno plot from G Sensor data (click to enlarge). We apologize for the car used in testing failing to reach 100 hp (stock D16, 140,000 miles).

The blue line to measured wheel torque, red is power and the green line is calculated aerodynamic loss, which is used to compensate measured torque to that as measured by a dyno.

How does the G Sensor compare to a Dyno?

Typical repeatability of the G Sensor dyno plot with back to back runs is plus or minus 1% engine output. Runs performed under different conditions (e.g. weather, tire pressure, wheels) will be different, but the repeatability of the G Sensor is generally good. In the future correction for temperature and pressure might be added to HondaLogger.

The resolution of the G Sensor in determining a change in engine output is about 2 hp. We will update this figure as we conduct further testing.

Comparing the results of the G Sensor with a conventional dyno shows a difference between the Dyno and the G Sensor.  Initially is appears that the G Sensor reads less power than the Dyno by about 10%, but we will have to test more vehicles to refine this figure.  Real world engine output as measured at the wheels varies with the gear used during the acceleration run, as the engine will use more energy to overcome engine inertia in lower gears. A lower gear will give less output and will raise the peak power and torque rpm. In our testing we found that 2nd gear gives about 5% more power at 300 rpm lower than 1st gear, while 3rd gear gives 5% more power again than 2nd gear at about 100 rpm lower than 2nd gear. This inertial effect accounts for some of the difference between the G Sensor and Dyno.


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