Good catch Bill. I also suggest getting into the habit of
pulling the engine through 6 compression cycles on post flight checks once in
awhile. You will quickly develop the 'muscle memory' that will tell you
right away if the compression is going screwy.
Compression is the best indicator for health of a rotary.
I agree with Lynn that it looks & sounds like possible
detonation damage. Always happens first on #2 rotor for reasons
Ed gave. Detonation is pretty rare on NA rotaries unless the ignition
timing is too advanced. Check it right away. You
have a fairly early EC2 and if you haven't already gotten them, I would
gladly give you the latest upgrades in return for being one of the
early pioneers crazy enough to try this stuff.
BTW, is that oil control ring in the photo damaged or is that just some
carbon & grease on it?
This is going to sound nuts at first glance but don't be too envious of
those monstrous intake ports on 3rd gen, Cosmo, and 20B engines.
I think it is a very deceptive thing. What you are seeing in them is an
angled cross section of the port runner due to the almost vertical intake
manifold entry angle on these engines. If the runners are coming in
more horizontally (like most of us are doing) the large external port opening
represents a drastic change in cross sectional area which is a BAD thing.
Note that the actual port opening into the chamber is about the same as earlier
13Bs.
Here is a picture of what I am doing on my 20B to keep runner area constant
until it gets to the port entry to chamber. I used a piece of thin
aluminum to sleeve down the port. The upper part above the sleeve was
later filled with epoxy filler.
Tracy Crook
----- Original Message -----
Sent: Tuesday, June 27, 2006 10:30
PM
Subject: [FlyRotary] damage report
Quick report: With over 400 hours on my engine, I was in the
process of testing the pressure differential across various points on my cowl
in search of more effective outlet for cooling air.
The idle has been getting rough for the last several weeks, and my
testing runs made me think it was getting worse. Since we all know it is
important to "listen" to your engine when it is speaking to you, I started
(again) to try to track down the cause. New plugs would help but only
for a few minutes. Tried switching coils and injectors on and off, but
no change. Seemed to be running very rich at idle no matter what I
did. Manual leaning would not make it smooth, but it would kill the
engine! All was smooth above about 2500 rpm.
Finally pulled the schrader valve from my compression tester and spun it
with the starter. Rotor one was a nice 100-100-100 for bumps.
Rotor 2 was 60-60-85. Oops. Looks like a bad apex seal?
Just tore it down today and attached is a photo of the broken apex seal.
Also found a chip from the outer (compression side) oil seal on that
rotor. Not shown are the SIX missing (melted??) rubber plugs from
the corner seals, and two corner seal wire springs that are completely
missing! The ones remaining are completely flat and looked like they
were disintegrating from heat.
Rotor one looked to be in good shape all around. Rubber plugs were
hardened, but still functioning, and the wire springs were
springing.
I can see that maybe if the rubber plugs melted, it would allow the small
triangular part of the apex seal to drop down and somehow allow the longer
piece to break. Does this sound reasonable?
LARGER QUESTION: It is obvious to me that a LOT of heat was
generated to melt the rubber plugs on BOTH sides of the rotor. Does
anyone care to venture a guess as to why that rotor was so much hotter than
the other? The EGTs were within a few degrees most of the time. I
will double check the oil jet that cools the rotor tomorrow.
(Jason just about has his 3rd gen back together. I am eyeing the
size of his intake ports....................)
--
Bill Eslick
www.weslick.com
Homepage:
http://www.flyrotary.com/
Archive and UnSub:
http://mail.lancaironline.net/lists/flyrotary/