Hi Chris,
Good to hear you are making progress on
the problem that side-tracked you from your engine tuning.
I have a street ported turbo block 13B
(sans turbo) and here are some observations that may (may not) help.
The fact that both pairs of you injectors
click when in simulations mode indicates that at a minimum you have good EC2
connections and power to both sets of injectors. I find that my engine
will run on either pair at any rpm below 6000 rpm. However, at lower rpm,
I must temporarily enrich the mixture manual before turning off the
primaries or it will miss and likely died when switching the primary off and
the secondary on. I can achieve 6000 rpm on primary or secondary injectors
only. I am using the 460 cc/min injector size for both primary and
secondary.
Your simulation test indicates that both
sets of injectors are wire to the EC2 correctly and functioning as attested to
by their clicking. So that would indicate to me only one condition that
fits the symptoms you describe.
- The
EC2 is not staging properly (for what ever reason)
IF the EC2 (for whatever reason) is not
staging (turning on all four injectors) then you could get the indications you
see. The * at WOT is I presume (I don’t have an EM2) and
indication of the EC2 firing only the primary injectors. So that also indicates
the EC2 is not staging. I think the most likely reason (again assuming no
malfunction) is that the staging point is not set properly.
Since the EC2 uses manifold pressure
to decide when to stage, the first thing I would check is whether you staging
point in the EC2 is set correctly. I know of one flyer who intentionally
sets his staging point very high (like above 29.92” Hg) so that all four
of his injectors are only firing when he is running boost. In other word,
he intentionally runs on only two injectors – the primary set –
most of the time until he hits his boost point.
IF your manifold pressure staging point
were set too high, then you would get exactly the symptoms you are
seeing. The EC2 simply never reaches the staging point and therefore only
the primary injectors are ever activated. That is the only thing that I
can think of that would cause the effects you are seeing.
At least that is my take on it. Tracy, of course, would
be the one to provide the definitive word. IF I were you I would check
the manual and find out which mode controls the staging point and then use the
procedures in the manual to set it to back to default. This should bring
the staging point back down to 15-17” Hg and IF this is the problem –
solve the problem.
All I can think of to suggest.
Good Luck
Ed
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Christopher Barber
Sent: Tuesday, December 16, 2008
2:27 AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Injectors
& Indicated RPM's questions
Now that I hopefully have my strakes mostly repaired I am
able to focus on the engine again. So, in that vain I have been able to
run it the last few days trying to get it tuned properly and hopefully
reliably. We have had some cool weather.....heck, for Houston it has been downright cold dipping
into the mid 40's, thus allowing me to run the engine at higher power settings
for a bit longer. Also, based on discussions here last week I am
modifying my cooling system a bit...I have had my small hose opening on my rear
iron plugged up to this time, but will modify when my new aluminum expansion
tank arrives. Funny, after following rotary stuff for years I missed this
apparent cooling convention.
One issue I am having is that regardless of how high I push
my rpm's it appears that I am only running on the primary injectors. The
EM2 continues to display the asterisk even at WOT. Also, when I shut down
the primaries at high rpm's (well over the staging point....3000 ish?) the
engine dies...actually, it dies whenever I shut the primaries off but I would
expect that at lower rpm's and idle (kinda rough idle around 1500 rpm, but also
kinda expected with a medium street port). So, to confuse me more in
my initial diagnostic I shut off the engine, kill the fuel pumps and place the
EC2 in Mode 1, injector diagnostic. All four injectors fire away....I
shut off the primaries and the secondary's chirp away. I shut off the
secondary's and the primaries still clatter on. This is what I expected,
it just is not doing the same thing when the engine is actually running.
Thoughts?
Also, a second issue, one I was just starting to try to
solve when my strakes became the priority, is that as I approach 6000 rpm on my
EM2 display the indicated rpm starts jumping all over the place....1200, 3543,
3333, 2650, 6314.......randomly. It is doing this even though the engine
is still developing more power, obviously over 6000 rpm...as you can tell by
the sound and the increased power. As I throttle back to about 5900 the
indicator starts displaying as expected again. Additional thoughts?
As always thanks for your consideration and insights.
Finally, it is kinda kewl to have the "airport
types" stop by to comment on the noise.....music...noise....music....all
in the ear of the listener <g>. Today Gary Hunter, a name well
known to most fast glass guys (he is also the crew chief for Bruce Bohanon's
Flying Tiger) stopped by and said it sounded "strong".
Wahoo. Gotta take the small victories.
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