Compression Testing Myths & Facts

[RotaryDiagnostics]

Originally Posted by Phoenix7

Great post! I will have to copy and sticky this into the General Rotary tech when it's done!

Now, why is it that the numbers change so drastically with the pedal depressed?

Keep it up and many thanks for helping clear up any incorrect info out there.

Thanks!

As Mobius indicated, I believe the difference is in the volume of air the rotor can "suck" into the combustion chamber--more air, more molecules, more pressure. The throttle plates when closed (gas pedal not depressed) will limit the amount of air available during an intake "stroke".