<snip>

The physical displacement value that makes the most sense
is 3.9 liters. That is what Vance claimed and he was right.
All three chambers in both rotors.

It obviously does not perform like a 3.9L four cycle engine
nor does it perform like a 1.3L four cycle engine. So something is
obviously wrong with the 1.3L displacement designation.

It performs like a 2.6L four cycle piston engine and a 1.3L
two cycle piston engine. In that sense a 1.3L two cycle piston
engine is really 2.6L actual displacement as it has two chambers
per piston. One does the intake and compression and the other
does the expansion and exhaust.

Paul Lamar ...No rotor no motor.

Thanks Paul,

I've been sitting on my hands to stay out of this discussion, but that
is the point I would have made.  The rotary is "equilivent" to a 4
stroke piston engine of 2.6L displacement as Ansdale said, but it's NOT
a 4 stroke piston engine, it's a 3.9L Wankel rotary.  Since most any
turbocharger of interest was designed for a piston engine, that would
be the correct displacement to use when setting the parameters for the
rotary.

Just from a paperwork standpoint, I would prefer to list my 3.9L engine
loafing along at 200 HP as opposed to claiming I was pushing 200 HP out
of a 1.3L engine.  Not that it makes any real difference, but it sound
better to a culture that's only familiar with piston engines.

Bob W.