• Measures cylinder volume (Volumetrics ™)
  • Calculates compression ratio
  • Locates top dead center
  • Compensates for spark plug volume
  • Compensates for temperature
  • Noise isolated
  • Portable


The CompRatio™ System combines an upgraded Volumetrics ™ Instrument with computer signal processing to measure cylinder volume acoustically. For combustion cylinder measurement, simply remove the spark plug, install the spark plug adapter, insert the transducer (whistle) and connect the Volumetrics Instrument via USB cable to the included laptop computer. Both average and instantaneous volumes are displayed in cubic centimeters by the CompRatio™ Application software.

The CompRatio™ System is powered by 110 or 240 VAC. It requires clean dry air (Maximun of 60 psi, at a nominal flow rate of 62.5 SCFH) to function properly. The system is temperature compensated and can be used to measure cylinder volume of both hot and cold engines. Accuracy is also insensitive to typical shop noises.

The CompRatio™ System includes an external Reference Volume (100cc with 97mm bore) for fine-tuning the calibration prior to making critical measurements. The System’s accuracy is within 1.2% of volume reading, and compression ratio within +0.1, when using a similar bore calibration file. Standard volume measurement range is 30-1200 cubic centimeters.



CompRatio-D3 Datasheet

Volumetrics Instrument ...

Last Modified: Jul 17, 2017 @ 3:48 pm