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


The CompRatio-D4(E) quickly and accurately measures engine cylinder volume with the Michigan Scientific new proprietary acoustic technology. This system is designed to simply replace the spark plug with a specialized adapter and insert the D4(E) probe. It accurately measures a wide range of cylinder volumes and quickly displays the measured volume within seconds. Automatic compensation provides for accurate measurements over a temperature range of 0-40C (0-95% humidity, non-condensing).

The D4(E) measurement system is designed to be simple and easy to use. It has a DC powered interface electronics box, which provides a digital readout of the volume obtained from the short measurement probe (<22cm long) allowing it to be used in internal tight spaces. The instrument is powered by an off-shelf AC/DC wall transformer. Innovative construction allows the D4(E) to be operated in noisy environments, while still making accurate readings. It also has internal temperature compensation and can be used to measure both hot and cold engines.

The D4(E) includes an external reference volume for compensating changes in ambient conditions between measurement intervals. Through the use of ambient compensation, the D4(E) is capable of an accuracy of better than 1% of volume reading. The volume measurement range is 15 to 1200 cubic centimeters.

Ordering Options

The adapters and reference volumes are made to order. For adapters, users will be required to specify the adapter thread, reach, and seat of the intended spark plug at the time of order. For reference volume(s), the desired bore, volume and material type (stainless or titanium) will be specified at the time of order.



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Last Modified: Mar 9, 2022 @ 7:57 am