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#1
05-10-2006, 11:54 PM
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How do you calculate an engines CR by doing a compression test? Ive never heard of this being done.
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#2
05-11-2006, 02:18 AM
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Did the 90 PSI compression test involve any leaks?
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#3
05-11-2006, 08:49 AM
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my 11.5:1 cranks 225.
__________________
69 GTO 11:[email protected] all balls no bottle 406 d-port iron heads 3700lbs all steel |
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#4
05-11-2006, 09:10 AM
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JDMERK, you are correct, you can't compute compression ratio by knowing the cranking compression. the only way is math, or computers and know all of your specs. i was just surprised by the difference in my car. by all my numbers i only rased compression from 8.25:1 to 8.86:1. the cranking compression went from 90# to 150#. the only other change is the lash setting, tightened it up from .030 to .024, this might be what changed things the most. pontiac jack the cylinders that only had 2.5% leakdown before were 90#, so no leaks. cgeis, yes on a flat top piston 10cc total volume change(head and gasket) will change from 11.6 to 12.93, but when you start with a 43.8cc dish piston, 8.52 it only goes to 8.86 with the same 10cc diferrence.
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