The geometric definition of displacement is the max volume
of a chamber. Period!
Paul Lamar

(snips)

Hate to 'pick nits', but I thought the definition was the volume
displaced by the piston (for piston engines) when moving from BDC to
TDC, & changes in piston crown, combustion chamber volume, spark plug
reach into the cyl, etc. would have no effect on displacement.

Enlighten me if I'm mistaken.

Charlie

You are correct Charlie. The above is an over simplification.

Paul Lamar

JMLBlues@aol.com wrote:

Also known as "swept volume," which is a nicely descriptive term.

BTW I am not sure if this was clear in my orginal message
but most Mazda people accept the displacement as twice
the swept volume of one chamber times the number of rotors as the
displacement of the engine. One chamber for a 13B would be 
654 CC I think. One power pulse per rev just like a one 
cylinder two cycle piston engine.

So the engine is 1.3 liters for two rotors.
Therefor a 2 rotor 13B is considered equal to a 2.6 liter four
cycle piston engine and I think the countries that tax by 
displacement use that number as do all racing organizations. 
I could be wrong. 

Vance would have us believe it is really 3.9 liters or three times
the real displacement of two chambers.... I think.
Is that right Vance?

The very interesting chart below from Kenichi's second Rotary Engine
book (1981) shows how the chamber volume changes with output shaft
angle.

volchang.jpg

Paul Lamar
 
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