Compression test numbers and math
01-31-2010, 01:00 PM
#1
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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 
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
01-31-2010, 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
http://foxed.ca/foxed/index.php?page=rotarycalc
Let me know what you came up with plz.
Grtz
01-31-2010, 02:47 PM
#5
@!!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
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; 01-31-2010 at 02:50 PM.
01-31-2010, 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..
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..
01-31-2010, 06:13 PM
#7
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someone's engine is toast...
02-01-2010, 12:47 PM
#15
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did you then multiply by 1.039 and adjust for cranking speed?
02-01-2010, 05:17 PM
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02-02-2010, 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?
this is what i got from Tustin Mazda when i got my car back..are these good numbers for a compression test?
02-02-2010, 10:11 AM
#25