Forced Induction Custom FI Setup Questions

My Compression Numbers

Old Sep 2, 2005 | 05:36 PM
  #1  
nonvtec's Avatar
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Default My Compression Numbers

Dry:
125 120 125 125
Wet:
140 130 135 135

With the vitaras c/r is like 8.4:1, what do you think? This motor (D16y7) has 10K miles on it.
Old Sep 2, 2005 | 07:07 PM
  #2  
D16Y8-Z6's Avatar
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Default Re: My Compression Numbers

Terrible. IMO.

My 7.5:1 cr d15 just pulled 178,172,165,168 cold a few days ago.
Old Sep 2, 2005 | 07:32 PM
  #3  
Spenser's Avatar
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Default Re: My Compression Numbers

yea, 140 is low espicially wet.
Old Sep 2, 2005 | 07:36 PM
  #5  
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Default Re: My Compression Numbers

throttle posistion makes no difference.
Old Sep 2, 2005 | 11:33 PM
  #7  
JDMFantasy2K's Avatar
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Default Re: My Compression Numbers

yeah like they said, throttle open, all plugs out, and i usually do 5 cranks. But make sure you do 5 for all cylinders (or 4 for all of them, whatever). Also if you re-do it, tell us the reading of the first crank, that can be importnant as well. Otherwise sounds like it's time for a cylinder leak-down test.
Old Sep 2, 2005 | 11:40 PM
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leed's Avatar
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Default Re: My Compression Numbers

IMHO, as long as the #'s are relatively close to each other, its good.
The shop where I work on my car has 4 diff. comp testers. They all read different from each other; like a 5-25psi ------. I freaked out when my 9:1 GSR tested at 150 accross the board, then I used another and got 185 accross the board.
Just stick to one tester, get a good baseline when you know the engine is healthy, and retest/compare against those #'s when you think you've fucked something up down the road.
Old Sep 3, 2005 | 09:45 AM
  #9  
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Default Re: My Compression Numbers

yeah, the best bet is to do a leakdown test along with the compression test. they go hand in hand, and can tell you alot of vital information about the internals of your motor.





sean
Old Sep 3, 2005 | 11:06 AM
  #10  
evosol's Avatar
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Default Re: My Compression Numbers

^^ i agree, if they're all relatively close then it should be all good.

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