To figure out the *theoretical* maximum cylinder pressure, you need to
add atmospheric pressure to the intake vacuum reading and multiply the
total by the compression ratio. However, although this gives the total
pressure on the intake charge (just atmospheric pressure yields numbers
that are obviously too low), it doesn't take into account the cylinder
filling efficiency (actually, inefficiency) of a given engine and other
losses in the system, which will lower the real world pressure. BTW,
cylinder volume, in and of itself, will not have any effect on cylinder
pressure -- it's the *charge* volume that counts (the charge is being
compressed, not dead air in the cylinder).
The best way I know to determine what your cylinder pressures should be
is by example.
Hope this helps!
-Schuyler
--
Schuyler E. Grace
'73 Spitfire 1500 - FM1183U
schuyler@bellsouth.net
schuyler.grace@atl.frb.org
http://members.tripod.com/~schuyler/
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