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Re: [LML] Re: LOP vs ROP Climb: Time and Fuel Burn
(LIVP)
Your exhaust tunnels might be the component that favors this.
In my standard exhaust configuration, the high pressure area where
exhaust dumps under the belly would be higher in climb (nose up), and
this high pressure area curtails exhaust outlet, requiring additional
work to exhaust the gases, robbing some HP and thus amplifying
retained heat. Your tunnels carry the exhaust back to the low
pressure zone behind the wing root, and provides some facility to
exiting gases that benefit heat exhaust.
We would love to see a picture of these tunnels.
I would also encourage some comments about LOP climbs at MAP 34"
and above from the very wise George Braly. His advice will be
helpful. Most of the professional Advance Engine talk is for
either normally aspirated leaning or level cruise leaning via the
BMP.
Jeff L
LIVP
Jeff,
that's
interesting. I wonder why you get those high
temps.
I wonder
what is different in our engine setups.
my CHT's are
steady @380 in the max/max condition @140knots.
It's been
tested to 20,000 in that config.
CHT's get
better than that with less power or more
speed.
I have
exhaust tunnel extensions which seem to make a huge difference for
cooling.
also have
ceramic coated exhaust. I don't know how much of a factor that
is.
Some will
say that 2700rpm is a bad idea because of higher friction
losses.
On the other
hand the flame front always moves at the same speed so if
the
crank is
turning faster your theta pp (angle after top dead center where peak
pressure occurs) is bigger
and the peak
pressure is less. ....which seems good for everything. the
pulse on the crank
is not as
concentrated, the CHT's are lower. assuming everything else is
setup right.
Colyn
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