Yes, I've done tethered power runs. I tie the plane to the trailer hitch on my pickup, in front of my hangar. I'm a big chicken, but I have run it up to 2200 propeller RPM which is about 4800 engine RPM. That is 'take off power" which I have held for several minutes at a time with no water or oil temp problems. In the past, with the previous turbocharger, the boost pressure from the turbo was too high, and only about 1/2 throttle = about 35" manifold pressure with about 50" from the turbo to the throttle. Now that the turbo is more appropriately sized, the pressure differential across the throttle is less, and a run away boost condition is less likely. Now a quick shot of throttle is very controllable and the reset of the EC-2 has worked, which indicates to me that I can ground run at higher power for a longer period. I don't think I will be able to take off at full throttle. I'll limit throttle to some RPM or manifold pressure. I think I could possibly overboost the programming limit of the EC-2 or overspeed the prop.
Sent from my iPhone
Have you tried to tie it down a run it a full power for a minute or
two?
(Well, at least at the minimum power estimated to take off and
climb.)
Highly recommended before attempting any first flight.
Finn
On 11/29/2013 11:14 PM, shipchief@aol.com wrote:
I got a chance
to play with 89SE today, I've been running and tuning after
all the tribulations of making right an improperly
built engine with an improperly sized turbo.
Today I re-read Tracy's manual for EC-2 & EM-3 and
started/warmed the engine. Then I bit the bullet and returned
to the EM-2 default setting (Mode 1 power up). Just like I had
intended in my last letter. I tried auto tune with the EM-3,
but I had a steep slope on the EM-3 correction table graph. so
I had no way to establish a safe state of mixture beyond
ground running conditions.
Well it works a charm! I think it's flyable now. I taxied
about and gunned it a few times. I feel a transition when
injector staging occurs, and I could work on the low idle, but
most of the taxi, run up and a brief blast of pre take off
power all works well with the mixture knob at 12:00.
So I feel confident that 89SE can fly when the weather
improves, and I get the rest of the fairings on.
I'll do some more tethered high power runs and take
pictures of the EM-3 data page, and the dual manifold pressure
gauge, then go home and make another RPM, Boost & fuel
flow graph.
I'm collecting intercooler bits, with the intent that I'll
have everything together to install it on the engine, and
fiberglass up the inlet duct and sealed air exit. The only way
I could control heat on the engine water and oil was by having
the inlets & outlets of the heat exchangers be separate
from each other, so I plan this also for the intercooler.
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