Greetings,
As before, I'm going to be lazy and just post my
daily log. I'm sure the turbo flame subject will make you read it
:-)
Rusty
8-24-03
/ 8 hours / 1385 total
Finished up the top cowl tidbits, and tuned the
engine. The A controller was
perfect, with Tracy’s default
settings. I did set the staging
point at 18” MAP (12” vacuum, 14” vacuum indicated on my defective gauge), but
it ran OK before I changed this too.
So much for the good news.
The B controller was waaaaaaay rich across the board. I couldn’t get the mixture lean
enough, even with the mixture knob all the way CCW, so used mode 3 to reduce
the flow rate several steps to bring the mixture down to the point where I
could center the mixture knob. I
also set the staging point at 18” MAP on the B controller, but had to do lots
of fiddling with the mixture to get the low power and staging area to
behave. It’s odd, the mixture
indication on the AF gauge needs to be leaner with the B controller, than it
does with the A. In other words,
on the A controller, two yellow bars rich of center is what seems to run best
at low power, but on the B controller, it’s one yellow bar rich of center. If
you try to get two, it just won’t run right, and can be improved by turning
the mixture knob CCW. Very
strange. Don’t understand this,
but it works.
My theory, until proven wrong, is that the intake air
temp at the throttle body is pretty darned hot. Since it was 100 degrees on the ramp,
and I’m running a turbo with no intercooler, I can imagine this to be
true. The A controller
compensates for this by reducing the fuel flow to match the very hot air. The B controller doesn’t have a temp
sensor, so it assumes that the air isn’t so hot, and gives me far more fuel
than I need. Yep, that EM-2 would
sure tell me how hot the air temp is :-) In the mean time, I’m going to take
this as another reason to NOT boost the engine too much at low altitude, since
the air is so hot already.
Now, as for injector mismatch problems- it seems that
the only operational problem appears when you turn off the primary injectors
(wimpy over-rated MSD’s), and try to run at low power. At higher powers, the engine seems to
function OK, but I have to turn the mixture almost fully CCW to make the
engine happy at low power. I
don’t see this as a no-go problem, but would like to match these up better at
some point. I’ll be sending all
my unused injectors (2-MSD’s, and 4- Mazda 550’s) out to someone this week to
find out what they really flow.
While testing the engine, doing everything I could think of to throw it
off, I was going from idle to full throttle, then back to idle. A friend on the ground was shocked to
see a nice flame appear at the turbo exhaust when I closed the throttle
suddenly. I hadn’t noticed this
before, but I’m not surprised, or alarmed by it, because RX-7’s do it too if
you take off the catalytic converters.
What was more entertaining/disturbing was when I accidentally left the
cold start switch engaged while trying to start a hot engine. The engine was too rich to fire, but
the turbo ignited the fuel, and kept a continuous orange flame about a foot
long flowing out of the exhaust pipe.
I can live without seeing that again :-)
For the record, both the tiny tach, and the new Equus 8068 worked
perfectly. Static rpm at 30” MAP
was 4900, and at 36” MAP was 5400.
This is just a bit below the 5000 at sea level that I was looking for,
but I think I’ll leave it hear for now.
I’m pretty sure I have enough power to fly :-)
Finally, I took the plane for a spin around the
taxiway, and tried to clean the rest of the crud from the brake discs. About half way around the airport, I
noticed that the left brake pedal would sink if I held it. Knowing what this meant, I took it
back to the hanger and found that the flare fitting on the aluminum hose at
the brake caliper just decided to start leaking. After all the times I’ve tried to
over-stress these lines by standing on the brakes, it just decided that now
was the time to leak. By the time
I got back to the hanger, it was just dripping from gravity pressure. Just amazing. Of course now I have to pull the top
skin again to get to the reservoir when I fix the connection. Rats.