Another compression check thread
 

Searching though threads I see many get 3 sets of numbers per rotor. However my dealership only provided a range per rotor. I'm assuming based on the numbers below my car barley meets the minimum requirements of a decent running motor?

My invoice shows:

39819 1.00 Compression test completed all good at this time

Front rotor at 6.9 to 7.4 KG X 100
Rear rotor at 7.0 to 7.4 KG X 100
Min Spec is 6.8 KG X 100

I would Seafoam it and see how it goes....those #'s are at 100RPM...kinda doubt it...you need the pressure for each face...at the cranking RPM to have valid #'s

Unfortunately that is all the info my invoice provides. The dealership had my car for a few days and I picked it up as the service department was closing so everyone was in a rush to get out of there.

BTW if they do not have a record of my results then should I request them to do another test?

They should have it...there is a form that they use to get reimbursed from Mazda for the test They need the proper values to validate it...they do here anyway

The test was done early October so hopefully they did not delete it from their systems.

It's acceptible for them to provide the numbers for each rotor in a range. You don't really need to know the exact numbers for each rotor face, just that none were below 6.9 and none above 7.4 as in rotor #1.

However, these numbers cannot be evaluated without knowing the engine cranking speed at the time of the test and to normalize them to an engine speed of 250 rpm. Not sure what "X 100" means, but I seriously doubt that it was 100 rpm at the time of the test. If that were the case, they could not evalutate the numbers using the graph in the factory service manual. Compression results for this engine requires that they be normalized to a cranking speed of 250 rpm. I believe the some of the Mazda testers do that automatically so they would not have presented the results obtained at 100 rpm.

And if you expand the graph to include 100 rpm and extrapolate those numbers to 250 rpm, the numbers would be WAY above the standard line. See the attached example to help understand what I mean.

Well before I reply was you car running bad in any wya at all? Some dealers have there own testers and you'll have to convert to figure out if its good or not. The pass is 7.6 @ 250rpms if its below 7.6 its a fail at 250. Its too early for me to convert stuff, I gotta go tear a injector out of a z32 this morning good luck and be happy you dont have my Z right now.