I'm sorry to say that after my various adventures in "Rotary Land"
this last
year it's time to hang up my rotors and put a Lycosaur in my Cozy. My
wife
and aviation friends close to me were getting tired of hearing stories
of
excitement in the air and were urging me to give up on the rotary and
put a
"conventional engine" in my plane. I've wrestled with that decision
since I
lost an apex seal in December and last week finally decided to make the
change.
I found a Lycoming for a pretty reasonable cost that should perform well
in
my Cozy and I finalized the deal this week.
So, for those "Lurkers" on the list, have I got a deal for you -
especially
if you're building a canard pusher! I'm selling all my rotary related
parts
and thought I'd offer them on the rotary email lists first. EVERYTHING
needed to fly are here (except for a rebuild kit to repair the apex seal
issue). The items are:
1. Rotary Engine w/ at least 1 broken apex seal. Includes:
a. Mazda Oil Cooler
b. Howe Aluminum racing radiator
c. Atkins Intake Manifold with tuned extensions
(including injectors)
d. TWM Throttle body and fuel rail
e. MicroTech Engine Computer
f. Bosch 80A Alternator
g. Starter
h. Coils
2. Conversion Concepts Engine Mount (for Cozy)
3. Tracy Crook PSRU RD-1B 2.175:1
4. Tracy Crook Engine Monitor - EM-2
5. Custom Tuned Exhaust System (remember
this is a pusher application it is pointed
toward the prop)
The engine, mount, and PSRU have a total of about 100hrs of run time on
them.
The exhaust system has all of about 5 hours on it.
The attached pic's show the engine before I went with tuned intake and
exhaust.
I have $7000+ in the engine and all items in #1 above.
The engine mount was originally $650
The PSRU was originally $2800
The EM-2 was originally $950
The tuned exhaust was $700
I'd like to get at least $7000 for all of it.
Thanx,
Joe Hull
Redmond/Seattle WA, Cozy-Mark-IV - 71hrs (of excitement!)
Sorry to hear that Joe.
Who built the engine? What brand of apex seal
was it? In a properly built, non turbo engine, broken apex
seals are almost unheard of. In over a million miles
on the 6 rotary powered cars I have owned I never had
a broken apex seal. Non of them had after market apex seals.
All stock Mazda seals. Only one of my engines needed overhaul
and that was the 1973 12A in my RX2 and that was caused by
melting the neoprene coolant O-rings used in those days.
However, if the apex seals are improperly installed they can break.
High boost and detonation can break an apex seal but it
never happens in a normally aspirated engine with properly
installed Mazda apex seals. You have a strange case there.
--
Joe, one other question. Did you change the spark plugs
just before the apex seal broke?
-----------------------------------------------
I searched all incoming and outgoing email starting
in April 1998 for the term "broken apex seal" and I found
only one other occurrence in a non turbo engine.
We average roughly 900 emails a month outgoing only.
I have no count on incoming because much of it is deleted
as spam. That is about 50,000 out going emails.
That was Chuck Dunlap in Feb. of 2006 with two
piece seals he bought from Mazdatrix. They could
have been after market seals. I will ask Dave Lemon
on Monday if he was selling after market apex seals
at that time. After market seals got very popular
about that time. Recently I have spoken to Dave about
it and he said there "was a lot of junk out there"
I assumed from that he only sells stock Mazda apex seals
now.
There is another factor that might cause an apex
seal to break and that is running the engine without
apex seal oil. The MAIN function of the apex seal oil is to
cool the seal believe it or not. The seal runs
at about 500 F with oil coolant as it opens the exhaust
port. This is a remote possibility as cast iron seals
don't melt until 2100 F or so.
I expect FOD will also break a seal.
Paul Lamar ...No rotor no motor.
High mileage rotors (with poor lubrication?) might also break an apex if
the apex seal groove in the rotor
has worn into a "V" shape (wider at the opening).
I believe the Mazda spec for the apex seal to groove clearance is
something like .002-006
Lynn Hannover posted another test method where you stand a new (or
nearly new) apex seal on end in the slot,
there should be little or no movement of the exposed end, 3/16"
was end of life./
/Cary
So Joe's engine could have been re built with out of spec rotor
slots.
I have heard of people hammering the rotor near the apex seal slot
to close the slot up a bit.
Down load the shop manuals from this site to get the overhaul specs.
http://www.wankel.net/~krwright/cars/rx7/manuals.html
Paul Lamar ...No rotor no motor.
Hi Paul;
The V groove is far less likely than the ones you already mentioned.
S4(86-88) rotors are dirt cheap and plentiful - easier to just get a
good used one.
Never heard of hammering - don't know enough about the rotor material
properties to comment.
I believe Lynn Hannover also talked of welding additional material to
repair a damaged apex seal slot
and using a diamond file to bring it back to spec - although his welding
looked phenominal :)
Cheers
Cary
The other way of fixing them is grinding them out to 3 mm
and installing 3 mm apex seals.
Paul Lamar ...No rotor no motor.
Cary
Hammering, pressing, welding ( remembering it's cast) are all fine.
It's very hard to grind/ flycut/ wirecut to original 2mm slot, so the 3mm
would be my choice.
I guess the diamond hand file would be the choice for refinishing 2mm.
George ( down under)
BTW the 3 mm seals are much more robust when it comes to
detonation fracture.
Paul Lamar
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