If you haven't done it, spend some time with "Rotary Engines" by Kenichi Yamamoto.  Lynn sent out a link to it in 2008,
but I downloaded and started reading it on the treadmill last week.  The first chapter is some interesting history.  The
second is a lot of math, that some may find interesting.  I just skimmed it.  But starting in Chapter 3, it gets REALLY
interesting, and explains how a lot of these factors affect one another.

In particular, it explains what it calls a 3:3 burn pattern when there is a lot of overlap.  The first time around, the
three chambers have fresh charge, so they burn normally and produce power.  The next time around, the exhaust gasses
push back the fresh intake, to the point that the mixture won't burn.  So you get three unburnable charges.  The next
time around you get some mixture of unburnt charge from the previous, burned gasses from two cycles ago, and new mixture
from the current charge.  If that actually fires off, the next cycle will have an overload of burnt exhaust, and won't.
  Then it all repeats.


Lehanover@aol.com wrote:

In a message dated 1/17/2012 6:47:41 A.M. Eastern Standard Time,
msteitle@gmail.com writes:

     Lynn,

     Thanks so much for a very detailed reply.  It sounds like the
     factory EC-2 setting for advance will be pretty close for cruise
     (5200 rpm) mode for my p-port engine.  I usually lean pretty
     aggressively, so maybe a couple of degrees would be in order.

     Can you tell me if its normal for the MAP to be different for p-port
     engines, particularly around idle (1800 rpm)?  My MAP readings are
     approx. 17.0 - 17.3 at idle.  This is about 2" higher that with my
     side-port engine.  I'm thinking this is because of the much higher
     intake/exhaust overlap with the p-port engine.

     Thanks,
     Mark


Everything affects everything, all of the time.

So where the side port can have less overlap, or even no overlap in the
case of the Renesis, the Pport has a lot of overlap. So, the Pport is
easily affected by exhaust system and muffler design. At any particular
RPM a wildly differing set of factors plays out inside the engine. The
most obvious is the exhaust gasses re-entering the chamber diluting the
intake charge, and making it over rich (because some of the oxygen
bearing charge has be displaced and the fuel delivery has remained
unchanged. This whole scenario may change just a few RPM up or down the
range.

So you might get it idling really well today, and in the morning it
barely runs at all until the oil temps come up a bit. What could cause
that? The cold rotors are condensing fuel back into droplets, which
makes for less surface area to mate up with any oxygen, and the engine
is now very much over lean. Everything affects everything.

If you have fiddled with dirt bike engines, this all comes to be very
clear. There is a similar interaction between intake design and exhaust
design in a piston port 2 cycle engine.

Notice the strange mufflers on those bikes. A seemingly over sized
muffler ending with a very small tube that seems far too small to make
any power. And still it works.

The rotary is a 4 stroke Otto cycle engine that tunes like a 2 stroke
dirt bike engine.
Less so for little or no overlap. Much more so for lots of overlap like
the Pport.

So, it will never tune up in idle quite as well as a side port. But the
higher the idle RPM you can stand the better it will be. Another factor
that removes the engine from its car like idle, is the fact that the
prop load is higher than the engine would see in just stirring up trans
oil at idle. So instead of say 3 HP required to idle you may need12 or
15 HP to spin that prop even 1,000 RPM.

Your first Viking departure will make it all worth the trip.

Lynn E. Hanover

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