Hi everybody,

Well it is known from the Mazda Compression table that you should check your compression according to cranking speed.

So if for example your cranking speed is 250rpm and your compression is 830KPA can you safely predict that if your cranking speed were 300rpm your compression would be 920KPA????

I mean that we can use Mazda Table to find out what is the min and standard of a specific cranking speed BUT CAN WE USE THE SAME TABLE TO PREDICT ENGINE'S compression at different cranking speed? Is it safe this kind of prediction ???

If this prediction is safe someone can take a compression test and if the cranking speed is 200rpm and compression is 720KPA (lets say to all chambers and rotors) He/she can say that if my cranking speed were 250 my compression would be 830. Is this correct? or in the real case at 250rpm the compression may not be necessarily 830 KPA??

Thanks

 

That's the idea. In general and to a point, the higher the engine cranking speed, the higher the recorded compression readings. Readings recorded during a compression test need to be "normalized" to an engine cranking speed of 250 RPM in order to compare them with the Mazda specifications contained in the shop manual. Check out p.14-16 at the link below for more information.
http://www.rotarydiagnostics.com/Mod...20Abridged.pdf