In a message dated 5/23/2012 9:43:48 A.M. Eastern Daylight Time,
echristley@att.net writes:
Lehanover@aol.com wrote:
> So at each 100 RPM both advance
and retard timing from the set point to
> see that you are in the middle
of a range for that RPM. You may find
> some nulls that like a bit of
retard. This is usually a combination of
> header and inlet tract
design. Your combination is not like anyone else
> even if they look
identical.
I have played with the timing just a little bit. On
the computer I have to adjust by 0.1* at a time. I didn't see much
of
a change as I moved it up and down by 0.5 to 1.0 degree. I thought there
would be more benefit to getting the AFR
smoothed out, so I left it alone
for now. How large of a change in advance is necessary to start showing
up on the tach?
The mixture is more important for power. The ignition advance is a long
term power and longevity factor. Changes in timing are usually made in 2 degree
steps. Typical dyno talk is: make just one change. Make a big enough change to
make a difference. So you can see which way you are moving.
>
> Cylinder pressure developed BTDC
subtracts from torque, so less is more
> in the timing
department.
>
> Target water temp is 180. Oil temp is 160.
Above 160 oil is giving away
> power, as rotor face temps go way up and
limit charge volume. So, oil
> temp control is free HP.
>
> 1600 degrees goes with about 12.5 FA in most cases.
So far, I've
only been able to give the EGTs an occasional glance to insure I'm not melting
anything. They and the oil
pressure gauge are mounted to my left, and
everything else is on the computer on my right. Since I'm doing this in
my
suburbian driveway, I have to keep my head moving looking for the stray
soccer ball (no actual kids around, but you
never know). The highest
EGT I've seen so far is around 1500 (I need to tilt the gauge to eliminate
parallax error).
EGT changes so fast there is no way to observe it with
any clarity. I installed a second little dash with EGTs and tach just for that
reason. Then set up a movie camera to watch the gages. Race car drivers operate
in a constant helmet fire situation and come back in with gibberish for data.
Made every shift at 9,600 on the button, but the tattle tale on the tach says
10,300. Must be a bad tach. Bad bad tach. Shame on
you.
EGT probes beyond 3" just tell you the engine is
running. Daryl Drummond (Builds hundreds of rotaries for various racing
classes).
And built our first two race engines, says 3
inches from the port face and that is where mine are. I use cheap gages and
probes and replace them every year, and carry a spare of each with me. The EGT
data is only for WOT at some useful RPM.
For other than top load top RPM the heated (three wires) oxygen sensor is
the piece to use for mixtures.
If you lock up an engine or a reduction unit without the wings installed,
you might find the fuselage on its side in the drive with prop parts 100 yards
down range. Just a thought.
Lynn E. Hanover
I've got a line on some hangar space at a grass field 10 minutes
from my house. Then I'll be able to be a little more
studious of all
the engine parameters.
>
> Advancing the throttle from
fast idle to full power should be smooth and
> slow. If the timing is
fixed this is very important. For closed throttle
> and near closed
throttle, with poor cylinder filling fixed 20 or 22
> degrees is fine but
if you romp down on the power quickly that 20
> degrees is way to much as
wide open throttle at low RPM gets you nearly
> 100% or slightly
more cylinder filling.
if(WOT & (RPM < 4000){
ADV
<= 15
}
Setting the computer is easy. Knowing WHAT the
setting should be....
>
> Record
everything.
Currently, the only thing I'm not recording is the
EGTs. I have individual probes for each rotor, but I'm
considering
adding another probe, installing it at the exit of the exhaust
collector, and tying it into the MegaSquirt so that I can
record it along
with everything else. I would tie the two I have into the computer, but I
only have one ADC port left
on it. Would a combined EGT reading be
valuable when it is recorded alongside all the engine temps, timing, AFR,
RPM,
throttle position, etc?
>
> This information may
be worth what it cost you.
You do realize I'm printing out your advice
and keeping it with me as I work over the tuning
8*)
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