For those of you interested in the compression ratio deal.
I have not found a source or price on the devices which do this
measurement for you but have come up with a method
of doing it yourself.
Follow along <G>
Technically speaking, the compression ratio of an engine is the
comparison of the total volume of the cylinder at
the bottom of the piston's stroke divided by the volume of the cylinder
remaining at the top of the piston's stroke.
Measure the volume of the cylinder and combustion chamber at bottom dead
center AND at top dead center by using light motor oil.
This is not the most accurate method but it will allow one to determine
a very close approximation of compression ratio without engine
disassembly.
Another variable in compression ratio is the thicknes of the head
gasket. To calculate head gasket volume use the same formula that is
used in calculating cubic displacement. It just has a much shorter
height. Bore radius squared X 3.14159
X gasket thickness (stroke in cubic displacement formula)
Finally to find the compression ratio divide the cubic volume of one
cylinder by the volume of the head plus the volume of the head gasket.
Cubic volume for one cylinder/cubic volume of head volume + cubic volume
of gasket
There is a site which gives you a calculation script which will
determine your compression ratio for you located at:
http://www.ben.esu6.k12.ne.us/sblock/infrm.html
Volume Formulas
Change cubic centimeters to cubic inches by the formula ‘cubic
centimeters/16.387 = inches cubed. Then, using
CR=BDCV/TDCV, where
BDCV = Volume at BDC, = TDCV + piston displacement
TDCV = Volume at TDC, = amount of oil required to fill the
combustion chamber at TDC, as
measured per above.
piston displacement = pi/4 * bore^2 * stroke
pi = 3.14159
1 ml = 1 cc
Enjoy,
Jim
--
Rawchester, Neu Yawk
Sptifire MkII "HardWay" FC68436L Red, what else?
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