Thanks Skip. I'm still curious though as to why one single rotor rotary
engine develops its peak torque at a particular rpm and another similar
engine develops its peak torque at a significantly different rpm. (For
example compare the RotaMax 65 to the Aixro 50). There must be some
fundamental reason for the difference. When setting out to design a rotary
engine what would one do to to try to produce more power at lesser rpm?

Bill Hobson

Perhaps I did not explain intake tuning clearly.
Perhaps someone else will please take a stab at explaining it?

Paul Lamar


Bill,

You can't really compare the RotaMax and the AIXRO engine except for their
rough power output and both being naturally aspirated charge cooled
single rotor Rotary engines. The fundamental difference is the swept volume.

Looking at what little information I have gathered with respect to the
RotaMax it appears to be a 650cc charge cooled Single. The AIXRO has
got only 294cc, which is not even half of the swept volume of the RotaMax.
The basic charge flow seems to be fairly similar except for the AIXRO Kart
engine having an additional direct peripheral inlet port which is opened
from approx. 5,500rpm upwards. Which means it gets fresh air at ambient
temperature whereas the RotaMax will most likely see charge of some
120°C plus at WOT. This clearly limits the power output at high loads.
This was the main reason for Norton to re-design the Sachs motorcycle
engine design for their applications, thus duplicating the specific
power output.

Talking about volumetric efficiency: At MWE we measured V.E. of
110% plus at peak torque only due to a tuned ram pipe. Unfortunately
I personally don't have pictures of the MWE Twin where that ram pipe
is clearly displayed, but have a look at http://www.hercules-wankel-ig.de/
and go for "Termine + Events" / "Wankeltreffen 2004" where you can find a
picture of the late MWE Twin. Half the length of the ram pipes is well
hidden in the air box though.

Regards,

Martin.