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Issue: Too much compression

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Old Sep 16, 2009 | 10:46 AM
  #1  
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Issue: Too much compression

Hi everybody,

my engine works fine, I only recognized (maybe once a month) that the sound changes a little bit (above 100mph) - but only when it's really hot outside (this sound appears and goes away for more than 3 years now!).

So I went to my dealer today and asked him to check the compression, result:
12,8 10,4
12,8 14,5
14,9 12,5
(results in bar)
for reference, regular compression is around 6,9-8,5bar.

Can anybody imagine what this means in detail - maybe someone here with an similar problem?

Thank you very much for your help (I'm really lost at the moment :-( )
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Old Sep 16, 2009 | 10:59 AM
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From: Planet Earth
some seals are stuck.
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Old Sep 16, 2009 | 11:24 AM
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From: Smallville
I would question that the tester is working correctly.....

Also why are the results in 3 rows? Should be 2 rows of three entries to make sense with an RPM reference for each row??
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Old Sep 16, 2009 | 01:59 PM
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Hi there,

3 rows due to 3 "areas" from each rotor.... all measured with Starter RPM

"Tester?" That was my first question at my dealer (they measured some other RX8 with this test equip as well - without any trouble - I think if there would be something wrong, the test results must be lower, not higher?)

@nycgps: What seals exactly do you mean, any clue? Is there a chance to clean the engine?

THANKS!!!!!
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Old Sep 16, 2009 | 02:07 PM
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Possibly you have a boat load of carbon in your combustion chambers ?
Do you redline often ?
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Old Sep 16, 2009 | 02:41 PM
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Yep, I love my redline (minimum two times a day ;-) )
So normally no reason for carbon...?

WHAT IF I JUST CONTINUE RUNNING THE ENGINE? (so far 60000 miles reached)
Will this pressure (compresion = more than 210 PSI within the engine) destroy the engine????

Last edited by Daniel K; Sep 16, 2009 at 04:34 PM.
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Old Sep 18, 2009 | 09:26 PM
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Originally Posted by nycgps
some seals are stuck.
maybe in your brain since it apparently has severe compression loss






looks like they're using kgf/cm*2 units (note that 10.2 kgf/cm*2 = 145 psig), what was the cranking RPM?



.

Last edited by TeamRX8; Sep 18, 2009 at 09:38 PM.
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Old Sep 19, 2009 | 12:19 AM
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From: Planet Earth
Originally Posted by TeamRX8
maybe in your brain since it apparently has severe compression loss






looks like they're using kgf/cm*2 units (note that 10.2 kgf/cm*2 = 145 psig), what was the cranking RPM?



.
blah
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Old Sep 19, 2009 | 02:49 AM
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Take your life.

Last edited by arghx7; Sep 19, 2009 at 02:51 AM. Reason: drunk
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Old Sep 19, 2009 | 03:14 AM
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Cranking speed was 290rpm....
so thats still 210 psi (my bloody measurement) against 130 psi (acc. your table)... :-) :-( ???
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Old Sep 19, 2009 | 09:40 AM
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From: Smallville
Sticky seals will not raise compression...either the tester was wrong, or there is a horrid buildup of carbon on your rotor faces causing the tubs to be way smaller...this is unlikely because with that much carbon there would be seal issues as well......

Oh...did I say that the tester is likely wrong

Or you have a great motor and have nothing to worry about....

Or you have a blockoff plate on your exhaust
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Old Sep 19, 2009 | 03:02 PM
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From: Planet Earth
people cant get joke these days ...
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Old Sep 19, 2009 | 04:12 PM
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From: Cali
Well... with an alarm going off all the time with flashing lights...........
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