I think that I might have missed something along the way, but

isn't

there a

residual amount of pressure from the exhausted chamber that goes

into

the

intake manifold when the rotor passes the intake port, thus

creating a

pressure wave up the intake manifold? Or does a tuned exhaust

scavenge

the

last bit of pressure out of the exhausted chamber?

Inquiring(confused) minds want to know.
Brian Trubee

There is a small bit of comunication between intake port and exhaust

port on

the current (and peripheral port) Mazda rotary.   But, if it were a

major

factor, the new Renesis rotary would be a dud since it has no overlap

at

all.  The intake pressure characteristics will look almost identicle

to the

current rotary even without the exhaust factor.

 I agree that the exhaust pressure data on the chart under discussion

is

confusing, partly because it is hard to separate the intake & exhaust
pressure waveform in parts of the cycle.  Another confusing factor is

that

exhaust pressure readings can vary radically depending on

configuration of

the exhaust system.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

Tracy,

I was assuming that the reason that the two traces overlap (inlet

pressure and

exhaust pressure) exactly is that the two tracts are interconnnected via
the combustion chamber for that portion of the cycle.  I assume that the
exhaust exiting is sucking the new charge in across the combustion

chamber.

Now I am NOT a rotary expert, but can this be the case? - basically is

there

a time in the cycle that one apex seal is halfway across the exhaust and

the

inlet
port to that face of the rotor (that combustion chamber) is also open?

This

seems
to be the easiest way to get the two traces to overlap as precisely as

they

appear to.  Don't laugh if this is mechanically impossible - I barely

understand

how this darned thing works and have never taken one apart, so it is
a bit of a mystery, altho I *theoretically* understand it, and certainly
respect the motor.

Bill Freeman

The overlap you mention DOES occur but to see why it does not have much
effect you have to visualize the physical configuration of things when it
happens.  The chamber is near its minimum size at this point which means the
exhaust pulse must squeeze down to a very thin cross section, traverse the
flat section of the rotor, transition to the open depression of the rotor,
then re-enter and pass the thin section on the other side of the rotor face
before reaching the intake port.  This relatively long and tortuous path
attenuates the pulse to a small value.  Contrast this to the piston engine
where the exhaust port is right there next to the intake and nothing to
isolate them.

I think the seemingly identical pressures at this point on the chart are
more a result of coincidence than direct effect.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

 
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