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Brian,
I used to stumble/bog through the staging point and I also
found I had to increase the richeness of bins around the staging point to
preclude the bog. However, As Steve and Tracy have pointed out it is
possible to adjust for the "mismatched" flow across the staging point by using
mode 6. This adjusts the differential flow between the primary and
secondary injectors. Tracy and Steve both have explained in more detail
how to do this, so I won't try to repeat it here.
Using the method you and I both used, there is going to be
an increase in the MAP table around your staging point and again, you
considerably different in flow rates between primary and secondary may require a
different profile in your MAP table - I just don't know.
Ed
Sent: Wednesday, May 18, 2011 9:57 AM
Subject: [FlyRotary] Re: Engine Tuning
Yes, it does look like a steep
jump, although I arrived at that through a lot of engine running and found that
it allows a smooth transition through the staging point. Otherwise, it would
always stumble throught that point. I'll do some more engine runs and keep my
eye on the O2 sensor.
Brian Trubee
-----Original
Message----- From: Jeff Whaley < jwhaley@datacast.com> To: Rotary
motors in aircraft <flyrotary@lancaironline.net> Sent: Wed, May 18,
2011 5:05 am Subject: [FlyRotary] Re: Engine Tuning
Hello Brian, I put your values into a graph last night. I had the same
conclusion as Ed's reply below that you are probably too rich at the top end ...
also your transition from lean to rich in the 82-84 BIN area is too steep 12-76
from one BIN to the next at staging is questionableMy thou
graphed your was thinking the same as Ed after I
From: bktrub@aol.com
Subject: Re: [FlyRotary] Your Fuel Map: [FlyRotary] Re: Engine Tuning
Date: Wed, 18 May 2011 00:02:01 -0400
To: flyrotary@lancaironline.net
Ok, that is interesting. I forgot to mention that I am running 28 lb primaries
and 40 lb secondaries. Looks like I will be doing some more setting of the
tables and experimentation.
I do have an O2 sensor and monitor, so I'll be looking at that also.
Brian Trubee
-----Original Message-----
From: Ed Anderson <eanderson@carolina.rr.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Tue, May 17, 2011 8:28 pm
Subject: [FlyRotary] Your Fuel Map: [FlyRotary] Re: Engine Tuning
Hi Brian,
I have my fuel MAP values and comments (in blue) buried in your spread sheet.
IF I had to make a stab at this point and quick look, I would say you are
probably running excessively rich at your higher map values > bin pointer 75 <
bin pointer 103. See my notes. I took my MAP values (turbo block street ported
- good intake - no turbo) and converted them to your reference - that column is
in blue is my value for direct comparison with yours. Some places we different
but it probably doesn't really matter - in other areas where we differ, you are
running considerably richer than my engine.
I have the 2.84:1 gear box swinging a 74x88 prop and consistently get 6000 rpm
static on a normal day and can get up to 6200 on a colder day. My fuel flow
will range from 16.5-18 GPH on take off and has hit 20 GPH on a cold day. I use
a 91 Turbo block street ported sans turbocharger. I have a fairly decent intake
system (about the sixth version - so I did quite a bit of experimentation to get
it right and I think it's a pretty descent intake)
Do you have an air/fuel ratio indicator? If so I suggest you run your engine at
some of those bin numbers and record what it is telling you (lean, Medium Rich,
etc). While at higher Manifold pressure you do want an air/fuel ratio running
closer to 12.5:1, I suspect your air/fuel ratio may be even richer than that.
Now all of these comments apply to bin/manifold pressures in the non-boosted
range < bin 103 or so.
Take a look at my notes - it is possible your problem could be too rich. Too
much fuel in your mufflers getting ignited can certainly produce a loud bang.
Perhaps ignition could also cause it, but right now it appears to me you are
simply way too rich between bins 75-103. If you have an air/fuel ratio
indicator, I would try reducing the mixture in those areas.
Hope this helps
Ed
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