Effective compression ratios

[MHLIGGINS <MHLIGGINS@aol.com>]

     I found this chart in the Feb ‘98 copy of Chevy High Performance
magazine.  Thought it might be of value to some folk on the list.  The article
was about supercharging, but the principles are constant irrespective of how
the boost is added.  (They had several references to cold, dense air -- Scott
J. would be pleased.)  The chart should help folk understand why high octane
fuel is so critical as the boost goes up.


Effective compression ratios

Boost		2 psi	4 psi	6 psi	8 psi	10psi	12 psi

Static CR
7.0:1		  8.0	   8.9	9.9	      10.8	11.8	12.7
7.5:1		  8.5	   9.5	10.6	11.6	12.6	13.6
8.0:1		  9.1	  10.2	11.3	12.4	13.4	14.5
8.5:1		  9.7	  10.8	12.0	13.1	14.3	15.4
9.0:1		10.2	  11.4	12.7	13.9	15.1	16.3
9.5:1		10.8	  12.1	13.4	14.7	16.0	17.3

     Later.
     --ml
     Still Confused in Bucksnort.