rotory engine use a totally different type of tester.you can not get an accurate test on a regular comp. tester ..rotories use a specific tester it measures pulses not compression.. confused yet ? rotory engines work completely different from piston engines, dont say duh, yet..to measure the comp right, you dont really find out the compression ratio at all,(bear with me hear!!) it is not important anyway(?) you need to know about the apex seals, the compression will make an *** out of you quick, trust me!!a blown motor will make 125 lbs of compression with out a problem..if you have one good apex seal,you need three ,not one. A rotory comp tester checks for pulses from your apex seals,it prints this info on a paper simular to a lie detector test..it has numbers 1 thru 9 verticaly , as the engine spins over the needle moves up and down ,and draws a line on the paper, each pulse is raised the three pulses should be the same,8 is a good number.if the points are not even you have a bad apex seal,ie. bad motor. the tester also shows approx.ratio next to the number.

 

I thought that most people new this,

1st remove the One-Way valve in a normal compression tester and you have a basic Rotary Compressor tester.

Or

Build a Digital one like i did. ( Part: Computer, WinDAQ, Pressure transducer, Fitting for spark plug hole.

My .02

 

Well, it's obvious someone didn't do much reading before their first post.

We have chart recorders here at work. I was thinking that with a simple power supply and pressure transducer I could make my own rotary compression tester. I know other have posted about this, but the chart recorder makes it very simple.

 

NICE!!!

 

Or you can just hold the pressure release button on a standard tester while someone cranks and check the pulses, as well as an overall comp. number. Or remove the shrader valve as mensioned by rx7nut.