Chris,
The Bing carbs in my tests are pretty good up to about 3500 feet. Above that
they
start running rich.
A normally aspirated engine should provide at full throttle 75% power. However,
the Bing carb runs even richer that high, so the power is lost (overly rich)
and with the higher fuel flows flying higher does not give greater efficiency.
I normally have clients with a constant speed prop so full throttle (actually
just a bit less seems to improve MP and leaning) at 5000 RPM can use a bit
more leaning so leaning add on devices are available. If cruising at 7500, try
running it up to 5500 for a bit to clear the plugs before decent. Once you
pull back for decent, the engine will load up again, so I go back to 5500 to
clear the plugs.
Creighton Smith (96EG) on his 80 horse and some of my Mid West Clients have
added
a leaning device called the HacMan by Green Sky Adventures (GSA TECH LLC 326
Melrose Landing BLVD, Hawthorne, FL 32640). It works, as it robs the carb of
float bowl pressure and leans the engine using manifold pressure (MP). My
Kitfox
and Jabiru guys use it for flying in the mountains to get peak power for
takeoff and cruise. Of course, you must have an EGT gauge and since you are
worried about plugs and running without fouling a fuel flow meter would be nice.
Most of the time, plumbing is done from the cross over tube to the HacMan
as a vacuum source. If you have a MP gauge, I really didn't see much of a
difference
in the MP readings, so we just tee it there.
Creighton Smith made comments on it in an older thread. It works but the hoses
supplied are crap and the leaning knob is very sensitive and must be turned in
1/4 increments, then await the results, as it takes time for the pressures to
normalize, then adjust again. There are videos online by guys using this.
Also PUT THE HACMAN BACK TO FULL RICH IF YOU CHANGE THROTTLE SETTINGS as MP
changes
and the carb may lean out far too lean and kill the engine. Normally, the
Hacman is only used after level off but out west some need it for takeoff power.
Some of the videos are done at low altitude, it is better to do this once
higher and at cruise. With a fixed pitch your RPM should rise, the EGT rise,
and the Cyl Temp may rise in the Rotax. Readjust the throttle for cruise RPM
then adjust mixture again. This has been used successfully by many but do
install proper instrumentation. Also, this is not an authorized accessory by
Rotax.
Best Regards,
Bud Yerly
-----Original Message-----
From: owner-europa-list-server@matronics.com
<owner-europa-list-server@matronics.com>
On Behalf Of n7188u
Sent: Monday, February 14, 2022 11:14 AM
Subject: Europa-List: Question about cruise altitudes with a 912ULS
Dear Forum Members,
Quick question for those familiar with operating the Europa with the 912ULS
engine:
What would you consider would be the highest altitude for normal cruising with
this engine. Read "normal" were the engine is not running overly rich and
causing
other issues such as fouled plugs?
Yesterday I did a fairly long cross-country around Florida (about 3.5 hours
total)
and on the return flight I was getting beat up by turbulence at 5,500 feet
(can the Europa be rough on turbulence or what??).
I understand the 912 is still happy at 5,500 but what about higher altitudes. I
put up with the turbulence. Rather silly since I could have just tried to go
up to 7,500 feet) but not knowing if the engine starts running too rich to be
happy I just put up with it.
Best Regards,
Chris
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