Joe 2007-11-20 14:42:24
Looking to buy either a Jabiru or Rotax 4 stroke engine.
RELIABILITY is the most important factor.
Seems like the Jabiru should be better with lower RPM but believe that Rotax
have more engines in service and therefore more development time and hence
Any comments welcomed.
Michael coates 2007-11-21 07:09:00
Answer = Buy the Rotax…….
Ian donaldson 2007-11-24 18:19:22
Buy the Rotax!
I am also in the land of the Jabiru and much prefer the Rotax.
There are a number of reasons, but the Rotax is a well sorted engine with
great technical backup, where as I feel that the Jabiru is still being field
tested with their customers.
There have been many problems with my friends who have Jabs and none with
the Rotax owners.
Thanks Michael, thought being from Australia you would have been a Jabiru
fan.so guess you have had problems with them. Phil
Model flyer 2007-11-25 08:54:02
I was talking to the agent for the Eurostar here in Ireland and he
said that many prefere the Rotax option because it’s geared it can
turn a larger three bladed prop than the Jabiru. This gives better
take off performance and rate of climb. It also gived the impression
of better flying performance, however that I cannot comment on. Both
are very nice running engines.
modelflyer at antispam dot net
Antispam trap in place
Joe 2007-11-28 14:02:08
THat was my impression too that maybe the Jabiru was being field tested by
the customers at their expense. Seems to be more enthusiasm for the Rotax.
Joe 2007-11-29 08:03:30
Thanks for your input too. I can see the logic behind the gearbox giving
more power. I suppose it was the high revving engine that worried me most
but with todays technology then 5000RPM is no big deal.
Joe 2007-11-29 08:03:32
I’m still looking for a plane and have a few types in mind.
In particular I was also looking at the Zodiac XL which is supplied as
standard with the Jabiru or Rotax for similar cost. Cost is not the probelm
as I would rather spend say 2000 more and have the reliability.I suppose
the Zodiac Xl is a cleanish aerroplane but I’m tending to go for the Roatx
as no one seems to have a bad word for it. Have now heard of quite a few
problems with the Jab.
Thanks for your input.
Barnyard bob - 2007-11-29 08:03:34
If reliability is paramount, not cost…
Neither Rotax or Jabiru comes close
to Lycoming or Continental.
There is plenty of bad mouthing to be found for
Rotax, Jabiru, Continental and Lycoming…..
The trick is in separating the wheat from the chaff.
Barnyard BOb — Lycoming powered RV-3
Mirco landini 2007-11-29 22:21:24
These are the considerations on Rotax & Jabiru of a member of this NG posted
some months ago from Jez:
I’ve used/flown behind both, and they are very different. I have no firm
preference for one over the other, but have formed the following views based
on observations and experience.
The Jabiru is simple, light, easy to install and performs OK in a tractor
configuration. There have been reported overheating and reliability
problems when used as a pusher on some aircraft. It turns the prop at 3,300
rpm to produce it’s 80hp, which is fine for a relatively high cruise speed
aircraft. Fitted to a slow (60kt cruise) aircraft the Jabiru did not
perform well, as the small prop that the relatively high rpm demanded gave
relatively poor efficiency. The most notable deficiency was in take-off and
climb performance, which could not be easily corrected by reducing pitch
without the danger of overspeeding the engine in level flight at full
throttle. On a higher cruise speed aircraft, like the Jabiru kit, the
engine peroms well, and gives adequate climb and take off performance.
The 912 has a gearbox so will turn a bigger prop at lower rpm. This gives
much more static and low speed thrust, so improves take off and climb
performance. The downside is that the engine is more complex (gearbox,
water cooled heads, air cooled barrels, plus oil cooler) and heavier (it’s
also more expensive!). It has a proven reliability record though, and is
relatively insensitive to mounting configuration due to the water/oil
We found that fitting the Jabiru with a bigger prop and pitching it to limit
rpm to 2,900 gave better performance than the standard small prop when
fitted to an Easy Raider high wing, low speed, UK spec microlight. This
limited the engine power output to around 70hp I guess, but the gain in prop
efficiency more than made up for the power loss in practice.
Kevin horton 2007-11-29 22:21:52
I worked with Diamond quite a bit in the period when they were changing
over from the 912 powered Katanas to the Continental ones. Many customers
were very happy with the 912. This tended to be the customers that
understood that the engine was different from a Lycoming or
Continental,and needed to be operated and maintained a bit differently.
These customers tended to make TBO without difficulty. Customers that
treated the engine as if it was a Lycosaur had problems making TBO. In
particular, the local operator found that it was advantageous to change
the oil more frequently than Rotax recommended.
But most operators complained about poor climb performance, and many
potential customers did not want to buy anything that didn’t have a good
ole North American made engine in it. So Diamond, like any successful
business, gave the customer what they wanted.
There is a fleet of 912 powered Katanas here in Ottawa, and the operator
is still very happy with them, except for the climb performance.
I don’t disagree with your comments about performance (the 125 hp IO-240
poered Katana runs circles around the 80 hp 912 one) and resale. But I’m
still not aware of any reliablity issues with the Rotax 912, and it seems
that you don’t have any knowledge of specific issues either.
Kevin Horton RV-8 (finishing kit)