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What do those comp values mean?

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Old Sep 28, 2013 | 03:27 AM
  #1  
revivo73's Avatar
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What do those comp values mean?

Hello

I've come across an RX-8 advertisement which showed its compression tester values. The seller says the compression value of an unused RX-8 is 10.5 and the value of this one is 8.9. What do those comp values mean? Is the 8.9 value ok?

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Old Sep 28, 2013 | 07:22 AM
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Serious?

You've ruined my whole day already.

But here you go ... Post #8 and there's a beautiful graph as well.
Remember they should be normalized to 250 rpm

https://www.rx8club.com/new-member-f...4/#post3664045

Try doing some reading please
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Old Sep 28, 2013 | 08:55 AM
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Remember that compression ratio is not the same thing as a compression score

The compression ratio is (roughly) a measurement of the difference between the combustion chamber fully expanded vs fully compressed. The compression score is a measurement of actual pressure on a compression stroke of nothing but air, and the actual compression score varies by altitude, temperature, engine speed, engine health, tester methods, etc...

Last edited by RIWWP; Sep 28, 2013 at 09:45 AM.
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Old Sep 28, 2013 | 10:18 AM
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I would say it means the car has the new starter ;
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Old Sep 28, 2013 | 11:26 AM
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*facepalm*
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Old Sep 28, 2013 | 11:47 AM
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356RPM? , I don't see anywhere near that even with my brand new S2 starter and brand new battery.

Last edited by 9krpmrx8; Sep 28, 2013 at 11:23 PM.
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Old Sep 28, 2013 | 12:40 PM
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Seems high to me too...dunno
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Old Sep 28, 2013 | 06:47 PM
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Apparently your engine is in stupidly good condition.

Yes.



Stupidly good.
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