> From: "Creighton Smith" <crouton@well.com>
> Subject: Europa-List: Jabiru engines
>
>
> >>>>>One thing about Jabiru installation perplexes me: Every Jabiru
> installation I have looked at over the years has had presumed cooling
> issues addressed with little deflectors inside the cooling cowl which is
> part of the engine package.
> This is heartening since it shows they (Jabiru) have been paying
> attention. The perplexing thing is: why is there no provision for
> inter-cylinder baffling? <<<<<
>
Hello Creighton,
There is inter-cylinder baffling on mine, at least I think we're talking
about the same thing. Check the Jabiru factory website, or the Jabiru USA or
Jabiru Pacific for pictures and details. The so-called "gull wing"
deflectors that go in between the cylinder bores have been recommended to be
removed by the factory last spring, but they do still recommend baffle
deflectors above the cylinders. The arrangement that seems to work best on
airframes like the Europa or Lightning is baffles roughly 3/4" tall that are
installed internally in the head cooling duct from the inside wall, over the
top of the duct and down the outside to above the rocker arm area of the
heads. That prevents the air from blowing over the rocker arm area of the
head where it does little or nothing to cool the head, and instead forces
air through the cooling fins where it is needed to take heat away from the
heads. Mine has them on the left side, above and in between cylinder #2 and
#4 and also over cylinder #6, with the cylinder #6 baffle being slightly
taller and shaped more to conform to the profile of the cooling fin shape.
These balance the CHT temps very well between the cylinders. The baffling
needed on the right side on my engine (clys 1, 3, & 5) is much smaller and
more subtle because the right side runs a lot cooler due to the direction of
rotation of the prop. More air enters that side, and that side runs cooler.
These baffles are not installed by the factory because every engine
installation is different. What works on a Jabiru airframe doesn't
necessarily work on a Titan Tonado or Europa airframe. So, the factory
expects the owner to install the baffles and adjust them as needed. You also
have to get your carb jetted properly for the airframe and, along with it,
adjust the pitch or choose a prop with a pitch that properly loads the
engine to keep the EGT's in line. When you get the EGT's in line it helps a
great deal with the CHT's. The baffling does the rest.
In regard to the Rotec TBI, I tried to fit one in my Europa, but I couldn't
make it work because of a conflict with the engine mount and footwells in a
horizontal arrangement, and the distributors and throttle cables in a
vertical installation. Similar conflicts exist with the Lightning airframe.
Without a major redesign of the intake plenum on the 3300, something that is
beyond my machining skills, I don't see how you could make one work on a
Europa with the stock plenum without making the distribution tubing longer
and more complicated. I tried to talk the the Rotec guys into building a new
plenum for the 3300 that would incorporate the Rotec TBI in an updraft
arrangement. The Rotec folks clearly have the machining skills and other
knowledge that would be necessary to do it, but they are so busy building
radial engines they said they just don't have time. I do know of several
Rotec TBI's operating on Jabiru engines in other airframes, though, both on
the 2200 and the 3300. There are a few running Ellison TBI's, too, as well
as Aerocarbs. Don't look for Jabiru to switch to anything different from the
Bing, though. Their strongest desire seems to be to keep things as simple as
possible and for them, that means sticking with the Bing. I certainly would
love to have mixture control, though.
There is a way that you can lean the Bing carb, above and beyond what it
does itself. There's a little gizmo that is made by Green Sky Adventures in
Florida. This is a precision valve that allows you to adjust the air flowing
into the balance tube on the carb that normally goes between the upper side
of the diaphragm chamber and the airbox. By bleeding in ambient pressure
into the top side of the diaphragm on the Bing you prevent the needle from
rising just enough to lean the engine. I'm told by the folks at Jabiru USA
that you can achieve as much as a 1 gph reduction in fuel flow above 8000'
or so by using this valve arrangement. I haven't tried one, but I did notice
during the engine seminar that virtually every Lightning and Jabiru airframe
that was on the production line had it installed. There is also a version
that is designed to work on the Rotax 9XX series with twin carbs, as well as
most of the Rotax two bangers.
I talked to a company over in Greenville, South Carolina a while back that
makes custom direct injection systems for aircraft engines. They had never
done a Jabiru, but they were interested and said they could do it, but their
$4000+ price tag stopped me cold. There is ample room on the Jabiru head to
install direct injection.
Regards,
John Lawton
Whitwell, TN (TN89)
N245E - Flying
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