Date: Tue, 12 Nov 2002 17:35:21 -0500
From: Ferdinando Di Matteo <aroctech@domain.elided>
Subject: Commpression checks
Here is one to kick around, if I get a high reading at sea level, then
drive up to a 14,000 foot mountain top. would I get a higher or lower
reading then? Fred
My initial reaction would be to say you'd get a higher reading since
your compression gauge is measuring pressure relative to that in the
atmosphere, and the atmosperic pressure would be lower. But...less
dense air compressed with a fixed volume ratio would yield a lower
pressurized pressure. And my first-reaction argument is probably
cancelled out by the fact that the air being drawn into the engine is
at the same (reduced) atmospheric pressure that the gauge is relating
combustion chamber pressure to.