John and all,
Thank you for your message. What is most important is that fact that you
are satisfied with your engine.
I would beg to differ with some of the arguments you exposed.
> A while back the Jabiru 3300 with hydraulic lifters passed JAR
> certification. Unreliable? Funny, the JAR didn't seem to think so!
Nothing to do with the Jabiru, but we should be aware that an engine
certification doesn't necessarily imply "real life" reliability. Just
think of the Thielert or JPX engines.
>
> Like purging the oil system on a Rotax with every oil change, this
> tuning is just something you have to do
You just don't purge anything when changing oil on a Rotax : drain the
oil tank, put a new seal and filter, and pour fresh oil. We installed a
quick drain valve so the total time for an oil change is about 10
minutes including removing and reinstalling the cowling.
> The 3300 is a powerful little engine. It's simple and robustly built,
> far simpler and more robust that the Rotax. I've seen first hand how
> both engines are built internally. For incidence, the Jabiru has main
> bearings between each con rod on the crank, not just on the ends and
> in the middle like a Rotax 912/914. The crank in the Jabiru is much
> better supported than the crank in the 912/914. A quick peek inside
> each engine and seeing how they are built won't leave you with a lot
> of confidence in the robustness of the Rotax, that is for sure.
I too had the opportunity to examine the internals of bothe engines.
It is true that the Jabiru is simpler and far more lightly built than
the Rotax, but in my opinion there is nothing wrong with a short
assembled crankshaft in a rigid crankcase. Radial engines too have short
assembled crankshafts, and some of them are among the most reliable
piston engines in aviation.
Besides, there are no specific crankshaft related failures on the Rotax,
nor the Jabiru for that matter.
> Why do you think there are dozens of Rotax Service Directives to
> comply with? Hint: it's not because the Rotax's were reliable in the
> early days of production!
Any serious engine manufacturer SHOULD issue dozens of SBs, SLs, etc...
>
> The Rotax engines are very expensive for those of us on this side of
> the pond with the current exchange rate. Likewise, Rotax parts, when
> compared to Jabiru parts, are definitely more expensive, much more
> expensive.
Agreed.
> Oil changes with the Rotax are a pain in the ass compared to changing
> the oil in the Jabiru.
This is just not so, see above.
> The Rotax is a far, far more complicated engine when compared to the
> Jabiru. If you believe in the K.I.S.S. principle for aviation related
> components, this bodes well for the Jabiru.
Lord Hives, manager of Rolls-Royce during the war said to Franck Whittle
: "Give us your jet engine project, and we will soon design the
simplicity out of it ";-)
The early Jabiru were simple, but with time, they now have many many
more parts : hydraulic lifters, cam follower, crankshaft dowels, etc...
Many owners are afraid of the maze of coolant lines on a Rotax. But your
car has many of them too, albeit better concealed from view. And yet
would one say car engines are unreliable ?
What counts for an aero engines, is the thousands of operating hours to
make it reliable, not this or that mechanical choice (as long as it is a
sound choice).
> I also like the throaty, real airplane engine sound of the Jabiru over
> the whiny noise the Rotax makes.
Think of us poor pilots in densely populated Europe. We must overfly
thousands of people, and they don't like noise !
Rotax engines can be very quiet with their slow turning props.
Just my thoughts,
Best regards,
--
Gilles
http://contrails.free.fr
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