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Bill,
I have purchased the EC-3. Will this make
any difference in the difficulty of tuning? Is it a good choice for a PP
setup?
I’d imagine I should aim for around 7500
rpm for a RD-1C.
Bryan
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of wrjjrs@aol.com
Sent: Monday, June 21, 2010 6:41
PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: 13B
rotary engines
As a reference the original Powersport
13B P-port is rated at 210 HP normally aspirated. The fuel flows are very
similar to any other engine producing that level of power. Steve tells me that
they were seeing FF very comparable to an angle valve IO-360 producing
identical power. This engine was dynoed with butterfly valves in the
housing. These p-ports were 1-5/8' diameter optimized for 6000 RPM. The
engine would rev higher but you were already at peak power anyway. Larger ports
will make more power at higher RPM. Tuning will become more critical with
the larger ports. A personal anecdote here. I built a high reving motorcycle
engine in 1978 with all the "best" parts at the time. The engine was
unreal at high revs, but if you transitioned to anything below 4000 RPM by
shutting the throttle off and quickly opening it again the engine
would "catch" or hit an RPM plateau and would rev no
higher. In fact the engine would die if not returned to idle! This horrible
malfunction was TUNED OUT later, and the solution was surprisingly simple,
however difficult to find. The key here is that many people underestimate
the job of installing and tuning p-ports. There are two aspects, first the
initial install being sure there are no leaks . Then second, and most overlooked
is that the system must tolerate the heat cycles of a high power engine without
DEVELOPING NEW LEAKS for a long time. Powersport used an insert with o-rings
sealing the port. O-rings or other elastomers work much better than epoxy on
long-term sealing because there are different expansion rates between the port
and the epoxy. On a car you can usually get away with epoxy for a while.
An aircraft is a different animal. The aircraft engine needs to tolerate
80-100% power for long periods and then long cold-soaks on the ground. The
rotary is mechanically tough enough but you need to design your subsystems like
a race car that will see a 500 mile long straight-away! When Paul
Lamar ran one of the newsletter guys P-port Renesis at MazdaTrix, They got great
numbers, but only after changing to an intake that MazdaTrix had spent lots of
time tuning. P-ports will run great, and even idle well if not too oversized,
but don't expect the tuning to be real easy. Remember you are designing a new
intake, exhaust, and the equivilent of a new cam timing all at once. The rotary
is very much like a two-cycle in that respect. The results can be very worth
while if you understand the difficulty involved.
-----Original
Message-----
From: George Lendich <lendich@aanet.com.au>
To: Rotary motors in aircraft
<flyrotary@lancaironline.net>
Sent: Mon, Jun 21, 2010 2:36 pm
Subject: [FlyRotary] Re: 13B rotary engines
Not all P-ports are equal.
Talk to Bill Jepson ( on here) about
availability of new P-ports.
All this talk of additional power coupled
with an easier intake design has me thinking I should probably go this
direction with my Renesis. It’s still on the stand after rebuild.
I haven’t constructed the manifold yet
anyway.
I assume fuel flow will be higher than
normal?
Is slide throttle best option?
Need to search archives I guess.
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On Behalf Of Lynn Hanover
Sent: Monday, June 21, 2010 12:15
PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: 13B
rotary engines
In a message dated 6/21/2010 11:03:01 A.M.
Eastern Standard Time, rv-4mike@cox.net writes:
Thanks for the
feedback Lynn.
Unusual to see a "poor port design" actually aid performance.
It is not obvious until you start graphing
the open and close events, but the side port which uses the side of the rotor
as a shutter to open and close the port, offers Mazda great latitude in port
timing. In the periphery ported engine (both ports) it is impossible to
arrive at zero overlap, and have an engine that will produce any power at all.
The apex seal does not close off either port at all, it just valves gasses in
one direction or another.
In addition, the overlap of the periphery
ported engine is far more effective flow wise than overlap in the side ported
engine. One apex seal is above the intake port when the opposing apex seal is
below the exhaust port. Flow between the two is unobstructed.
So, at low RPM you get fresh mixture
leaving through the exhaust port, and combinations of burned and unburned fuel
and exhaust gasses flowing partway back into the intake runners.
This reduces the low RPM output to the
point that the engine seems quit docile, and is easy to drive around in the
car, slowly, or possibly taxi in an aircraft. This would make off idle
tuning data useless as there will be fuel burning right on top of the EGT
probes, and unburned fuel reaching the F/A sensor.
The engine will act along the lines
of a piston engine with a long duration cam. When the engine reaches its happy
RPM where all of the mixture is burning inside the engine, it will step up on
the "CAM" and you will see what a
good idea this was. Use slow throttle inputs until you find the "WOW"
RPM, and be ready with all available rudder.
When we first ran a factory periphery port
engine, we found that there were places on the track that would not allow full
throttle. This with 11" wide slicks. Thank Heaven for rev limiters. The
driver reported the rear end getting real loose cresting hills and bumps.
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