1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Mazda compression test results; feedback welcome!

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Old Mar 25, 2002 | 05:41 PM
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Suparslinc's Avatar
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Mazda compression test results; feedback welcome!

I had my car compression tested on Saturday at AIM in Indy. Heres what the readings were:

Front Rotor RPM 270
8.1/7.7/7.9
Rear Rotor RPM 266
7.2/7.7/8.0

I know the cranking speed is a little high, and it looks like I have a stuck side seal or something on the rear rotor with that lower than average 7.2. Also, can anyone out there convert these units to PSI so I have a better understanding of where my compression is? Thanks in advance!
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Old Mar 25, 2002 | 05:50 PM
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Felix Wankel's Avatar
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From: Birmingham, AL
1.0 kg/cm2= ~14 psi, so you have about

113.4/107.8/110.6

100.8/107.8/112.0

Not too bad. There's also an altitude compensation that I don't know how to do.
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Old Mar 25, 2002 | 05:51 PM
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What unit are they in now?

1 Bar = 14.5psi
1 kg/cm2 = 14.22psi

edit: too late Oh well... ATF the sucker and re-test it! (I had an engine that ran great at 25psi compression on all faces... go figure!)

Last edited by peejay; Mar 25, 2002 at 05:57 PM.
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Old Mar 26, 2002 | 07:31 PM
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85rx7blue's Avatar
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I'f I want a compression test can I just go to any mechanic and get it done?
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Old Mar 26, 2002 | 11:24 PM
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they have to use a Mazda compression reader. Alot of people say you can get a ballpark figure with a conventional tester, but I'm here to tell you thats not true it won't even be close. I was bumping something like 30 psi with a piston compression tester and as you can see the numbers are actually quite higher.
The dealer will want 60 or 70 bucks for a rotary compression test.
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