Lots of good stuff. Thanks John and Gilles and others.
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? Every air cooled engine I've ever seen has
these. (Lycoming, Continental, Franklin, de Haviland, Ranger, LOM, P&W,
VW, Porsche... all except Jabiru, free air or fan cooled.
Not only for cylinder and head temps, but for cooling drag reduction it
is a good thing to make all the air entering the cowling do good,
efficient work removing heat from the engine.
Why? What am I/we missing? Jabiru installations have huge passages
between cylinders and heads so a lot of air rushes through (because
there's less resistance) rather than being directed through the head and
cylinder finning.
I also agree that the Jabiru would benefit enormously from a 6-point
fuel injection system. Or perhaps 2 of the Rotec "injectors". It is
really hard to evenly distribute the relatively large fuel droplets
emerging from the Bing's mainjet well through the Jabiru's long,
serpentine induction passages. Liquid doesn't go around corners, it
sheets out on the outside of bends and crawls downstream.
The major users of diaphragm (constant velocity) carbs, (Bing, Mikuni,
Keihin) are motorcycles and outboards and they are mounted on a straight
through manifold as close to the intake valve as practicable. Not the
case on Rotax or, especially, Jabiru.
Sorry for the verbosity.
Creighton Smith
A-036
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