WINDOWSEET@aol.com wrote:
> Using the stock bore: 7.47cm (74.7mm) and the stroke: 7.6cm (76mm) I
> calculate a displacement of 332.9cc per cylinder and multiplying that times 6
> cylinders gives a total displacement of 1997.45cc- just slightly under the
> published displacement of 1998cc. It is obvious to me that the factory didn't
> take into account the volume of the combustion chambers in calculating
> displacement. Is this common practice?
Yes, this is the common practice.
If you think about what "displacement" means, it makes sense. It
is the amount of air displaced by the pistons in each cycle. The
air in the combustion chambers isn't really displaced, the pistons
don't forcibly remove that air.
In an ideal world with ideal fluids and no friction and
so on, one cycle (two crank turns) of an engine with a displacement
of 2L would draw 2L of air into the intake and push 2L out
of the exhaust. Obviously, there are so many reasons why
this isn't true in real life, but that's where the calculations
come from.
--
Trevor Boicey
Ottawa, Canada
tboicey@brit.ca
http://www.brit.ca/~tboicey/
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