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Glad to hear you are getting the "bug" worked out,
Tracy. I presume the increased loudness was not due to it being in the
hangar verse outside {:>)
Great to hear the non-return fuel system is working as
expected. Will want to know the details at some point.
Boy, I hope you are right about the friction. One
more rotor would, of course, increase that friction feel, but I figure
your arm should be able extrapolate between 2 and 3 rotors.
Certainly hope its not a seal out of place. I personally don't think it is
and here is my rationale.
First, When my apex seal (slightly misplaced to the side
of the rotor) incident happened, I would have not been able to turn the engine
over had it not fallen into one of the milled "lightening" holes in the rotor
(what are the odds?). Without falling into that hole, It would have had so
much pressure friction that I am certain I would not have been able to turn
it. It was hard as it was.
The second indication was that my engine would not
run/idle below 2000 rpm (due to the friction) until after about 1 hour of run
time - by which time the misplaced apex seal was probably worn into dust (and
the damage already done).
I don't recall the friction before and after the run, I do
know it was high before the run and it seems like it was still high after the
run - but, don't hold me to that.
But, if your engine has no problem at low rpm idle,
then its likely that is not the problem. Also if you have more than 1
hour run time it would probably have worn that seal down by now -
but I've been wrong before.
I'll be keeping my fingers crossed for you.
The only good news if you do decide you have to tear it down, it that you are
home rather than in a dilapidated garage in the middle of a Louisiana summer
with no rotor parts within 600 miles {:>)
Best Regards
Ed
----- Original Message -----
Sent: Monday, August 27, 2007 10:28
AM
Subject: [FlyRotary] Re: Latest 20B
testing
Finally got a moment to report on the RV-8 progress. I have about
2.5 hours of ground testing over the last month or so on the 20B RV-8 with
mixed results. The Bluemountain stuff is working great and the display
is crisp & bright in daylight as advertised. Very pleased so far.
The first attempted engine start after installing all the instrumentation
resulted in a loud bang followed by the sound of dripping liquid (I was inside
the hangar). The other 'first start' at last year's rotary roundup
fly-in was with no instrumentation and the engine temporarily 'hot-wired'
for the demo. Climbing out of the cockpit, I found gas dripping from the
exhaust pipe into a sizable puddle on the floor. Note to
self--- Perform all first starts outside in the future.
Problem turned out to be a misfire on one of the injector disable
switches causing always on injectors. After correcting that and clearing
the flooded engine, the engine started immediately and I thought the engine
sounded much louder than last year's engine run. Before I had just
the exhaust header on with no muffler or tail pipe and the engine was
surprisingly quiet. I had added the rest of the exhaust system up
to but not including the under belly muffler. I thought this might
make it even quieter than it was before but the opposite was
true. When throttled up to 24" manifold pressure the sound is
powerful and defening. I will need something bigger than my golf cart with
chocked wheels to test it at higher power. At 25" Hg and 5000
RPM It jumps the chocks and the RV-8 starts dragging it down the
runway even though the cart parking brakes are on.
Having no vapor lock problems so far with the non-circulating fuel rail
scheme. I used a remote fuel pressure regulator near the pumps (inside
cockpit) so the fuel goes only one way to the fuel rails with no return.
Return is from the regulator to fuel tank. This arrangement is used on
most late model cars and vapor lock does not seem to be a problem. On my
Mazda Tribute I do notice that on a hot start on a hot day there can be a
momentary stumble from vapor in the rail but it clears immediately.
Not sure why but this engine seems much more critical in mixture tuning
than any of the 13Bs I've run. The mixture control only has
about 70 deg. range where the mixture is OK which is about half the range
I have on other engines. The 20B injectors are about the only variable I
can think of that could affect this.
Cooling is surprisingly good. On a 90+ degree day the coolant
stabilizes at 200 F and oil at 185. This is much cooler than my RV-4 on
extended ground runs.
The bad news is engine friction that I notice when pulling the prop
through compression cycles. BTW, with only a little experience you can
gauge the relative health of a rotary with just a few pulls of the prop
through all 6 (or 9 on 20B) compression cycles. When cold this
20B feels close to normal for what I would expect on a freshly
overhauled engine considering it has one more rotor than my
13Bs. But when it's hot the internal friction is much
higher. When switched off after a run, the prop stops quite
abruptly. Immediately afterward, it will not rebound from a
quick pull into compression after releasing the prop. Hot starts
are very sluggish and sometimes not possible with the tiny battery I'm
using. I keep hoping this will change after break in but so far it
doesn't look good. OTOH, the Renesis took a full 40 - 50 hours to break
in. I do NOT want to open this engine again but it may be
necessary. I keep having nightmares of Ed's ordeal with an engine that
felt very similar to this. Time will tell. lots more things to test
before making that decision.
Tracy
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