[Wing] Jabiru 180 HP in Production

[Tedd McHenry]

Jabiru has announced that their 180 horsepower engine was released for
production in January.  There have been a few significant changes to the engine
during the development phase.  You can read more about it at

	http://www.jabiru.net.au/

I didn't see an announcement on the Candian distributor's web site, but if you
wnt to contact them they're at

	http://www.jabirucanada.com/

Displacement is down from 6.0 litres to 5.1 litres.  This was achieved by
shortening the stroke.  Reading between the lines, it appears that the
rod:stroke ratio was a bit too small in the original design, which would give
higher than ideal bearing loads.

The horsepower is slightly down (presumably as a result of the lost
displacement).  It's now rated 180 HP @ 3,000 RPM and 170 HP @ 2,700 RPM.  For
what it's worth, I did some calculations on these numbers and came up with a
few interesting results.  For those concerned about wear, the shorter stroke of
the Jabiru gives it a lower piston speed than a Lycoming, even at 3,000 RPM.
The Jabiru at 3,000 RPM has a piston speed that is 15 percent lower than that
of an O-360 at 2,700 RPM, and 4 percent lower than the O-320.  However, the
Jabiru does have a 5 percent higher BMEP (essentially equivalent to manifold
pressure).  One thing I noticed that's a bit odd is that the rating of 170 HP
at 2,700 RPM requires a higher BMEP than the rating of 180 HP at 3,000 RPM.
This suggests either that torque drops off significantly between 2,700 and
3,000 RPM, or that they're using different manifold pressures for the two
ratings.  Both explanations seem a bit odd, to me, and my calculations indicate
that the power should be closer to 160 HP at 2,700 RPM, which would make sense
for a 310 cubic-inch engine.

The weight is up slightly, from a projected 231 pounds to 257 pounds.
Nevertheless, for a complete engine with mags, carbs, exhaust, cooling ducts,
and alternators, it's still very light.

They are now developing a 50-amp alternator system, which they hope to release
soon.  This will be a dual 25-amp system, with both alternators directly on the
crankshaft, so it should be very reliable.

Jabiru is also working on installation kits for the RV-6, -7, and -9.

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Tedd McHenry
Van's Air Force
Western Canada Wing
tedd at vansairforce.org
www.vansairforce.org