I am thinking of offering a device to measure and record
the compression on a rotary engine.
Price would be about $60 for the sensor, power supply and spark plug hole
fitting. It would require a $90 Hytek data aq module.
http://www.hytekautomation.com

Similar systems from:

http://rotarydiagnostics.com/model_rect-03b.htm

cost $364 + $20 for shipping and handling.

Handy to check the condition of that engine
before you buy it. Use an impact wrench on the
front e-shaft nut to turn the engine over.

What do you think?

Paul Lamar