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Compression test numbers and math

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Old Jan 31, 2010 | 01:00 PM
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Question Compression test numbers and math

Hi guys I tryed searching compression test threads and could not find what I'm looking for

I need to know how to do the math with my compression test numbers?
Or is there something for me to down load that I can plug my numbers into for a end result?

I have a felling I need a rebuild and if thats the case this mt did not last any longer than my at did
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Old Jan 31, 2010 | 01:10 PM
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Have a go with this link:

http://foxed.ca/foxed/index.php?page=rotarycalc

Let me know what you came up with plz.

Grtz
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Old Jan 31, 2010 | 01:12 PM
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nice thats the tool i have to measure the compression
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Old Jan 31, 2010 | 01:30 PM
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Thanks! I download that and run my numbers and post them up when I get home.
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Old Jan 31, 2010 | 02:47 PM
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@!!narotordo PMed me his numbers and using the calculator this is what I got:

Original numbers:
F
060 057 059 @ 184 RPM
R
065 069 071 @ 191 RPM

Using the calculator (rounded):
F
82 79 81
R
85 89 91

Mazda's specs are:
Standard = 120psi @ 250rpm
Minimum = 98.6psi @ 250rpm

I know the calculator is useful for corrections, but wouldn't the numbers change if he was turning the engine quicker (closer to 250rpm).
I'm obviously no expert on compression testing

Last edited by Jon316G; Jan 31, 2010 at 02:50 PM.
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Old Jan 31, 2010 | 04:13 PM
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Mazda had the specs up @ 250rpm, probably because that is the rev/min it should hit during the test. Of course numbers could better a bit by having a bit more rpm, having a slightly better seal and less pumping loss.

But these numbers are down by quite a bit, roughly corrected even down bout 40% from "healthy". The 50 rpm short will def. not make up for this percentage.

Don't know the mileage and way of use, but seems to me before all else fails or pops up as a "diagnostic problem" i would personally opt to make the engine healthy again, so basically a rebuild, def. new seals etc..
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Old Jan 31, 2010 | 06:13 PM
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someone's engine is toast...
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Old Jan 31, 2010 | 06:22 PM
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Let's get some Iannetti seals and rebuild it.
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Old Jan 31, 2010 | 07:21 PM
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^Baller!

Yeah George its gone
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Old Jan 31, 2010 | 08:10 PM
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Yep - looks like mine:

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Old Jan 31, 2010 | 08:39 PM
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^Dude! where did you get that cool looking chart? and how do you read that?
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Old Feb 1, 2010 | 02:24 AM
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how about these numbers...(not mine)

26 21 24

191 rpm
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Old Feb 1, 2010 | 03:10 AM
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Gil, didn't you use the "Godfathers" compression tester?
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Old Feb 1, 2010 | 11:04 AM
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^Yes
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Old Feb 1, 2010 | 12:47 PM
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did you then multiply by 1.039 and adjust for cranking speed?
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Old Feb 1, 2010 | 04:45 PM
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How do you adjust for cranking speed? Gracias Jorge. Iknowyournotmexican.
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Old Feb 1, 2010 | 05:17 PM
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here ya go AJ http://virusakos.freevar.com/

whosaidIwasmexican?
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Old Feb 1, 2010 | 11:55 PM
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Originally Posted by @!!narotordo
^Dude! where did you get that cool looking chart? and how do you read that?
The word "compression"comes from an old Greek word I assume...

Gotta luv those those guys!
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Old Feb 2, 2010 | 01:18 AM
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rotor #1: 7.5, 7.2, 7.4 at 239 RPM and rotor #2: 7.5, 8.0, 7.7 at 238 RPM

this is what i got from Tustin Mazda when i got my car back..are these good numbers for a compression test?
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Old Feb 2, 2010 | 01:44 AM
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Originally Posted by volcomx31
rotor #1: 7.5, 7.2, 7.4 at 239 RPM and rotor #2: 7.5, 8.0, 7.7 at 238 RPM

this is what i got from Tustin Mazda when i got my car back..are these good numbers for a compression test?
Those numbers are pretty decent if you ask me ...
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Old Feb 2, 2010 | 01:45 AM
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Originally Posted by AJ's Shinka
Let's get some Iannetti seals and rebuild it.
SHHHHH ...

thats what im planning to do ... jesus how dare u ! u just told everybody !

Now I have to kill whoever knows my plan ... damn quite a lot of people to "finish" ...
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Old Feb 2, 2010 | 02:09 AM
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Just stuff them with that big cheesburger!
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Old Feb 2, 2010 | 02:16 AM
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decent as in my engine is in good shape?
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Old Feb 2, 2010 | 08:41 AM
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Originally Posted by Jedi54
someone's engine is toast...
Three someone's engines are toast...........The dealer will be busy today. Jedi, thanks to you and the others for coming on and giving the advise that you did. To be honest I forgot about the RPM correction.
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Old Feb 2, 2010 | 10:11 AM
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Originally Posted by Jedi54
here ya go AJ http://virusakos.freevar.com/

whosaidIwasmexican?
No one, but gracia jorge so hispanic. lol gracias again.
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