Comment

Comment by Robin Hilliard on November 11, 2012 at 12:48am

I know this thread has been quiet for a while, but I'm making the same decision for my 750 and thought I should point out something else people might consider. While I'm sure the Jabiru is a more practical choice being 21kg lighter for starters, the horsepower difference may not be as much of an issue, because the Rotec can swing a larger prop.

The recommended R2800 prop diameter is 76", and the Jabiru site recommends 60" for the 3300. If I plug the horsepower and prop diameters into the formulas from the Evan's Lightplane Designer's Handbook and estimate the 750's drag, the Rotec comes out with more thrust horsepower than the Jabiru at all speeds, especially near the stall (an additional 28%). The formulas also show the Rotec would have a better maximum rate (by ~ 100 fpm) and angle (by ~ 1.4 degrees) of climb.

Mind you, the Rotax 912S has similar prop rpm (and I assume diameter) to the Rotec, so the same formulas would favour the Rotax over the Jabiru. Given that it's also lighter than both the Rotax is probably the most sensible choice (much as it pains me to say it, being Australian and having gone solo / flown many hours behind a Jabiru). Does anyone know of some actual climb figures for 912S and 3300 powered 750s?

All this said I might still get the R2800 - I've never gotten used to the Rotax sound, and on floats it would look like a baby Beaver. Think of it as getting a Rotax and adding a very good 45kg sound system...

Cheers,

Robin

Comment by Phill Barnes on February 24, 2010 at 5:25am

Hi Guys
I have been in contact with Wayne Johns, the Jabiru fuel injection guru, and requested his permission to post his email address here for anyone who wishes to ask questions. He has just replied saying that this is not problem. Wayne is in very high regard of Rod Stiff, the owner and designer of jabiru aircraft and engines. So anyone wanting info, ask away. waynefixit@activ8.net.au

Regards
Phill Barnes

Comment by Bob Simmons on February 23, 2010 at 9:51pm

And Jay, I think you meant to web site for Jabiru USA for engine mount process, which is actually http://www.usjabiru.com/.

Comment by Bob Simmons on February 23, 2010 at 9:43pm

The 3300 is my choice too, and I'm extrtemely interested in what you might find out about fuel injection, particularly if it's intended to work on the 3300. I want to fly my plane in the wintertime and don't want to worry about carb icing.

Comment by Jay Parker on February 16, 2010 at 5:41am

Thanks Phil that’s very good news to hear. I'm still far from getting the engine and fuel injection, so I hope by then Jab and Rod Stiff have worked something out. Some folks wrote back saying that the Rotec Fuel Injector wasn’t a true fuel injector so an alternative is good to hear. I will archive this message from you in case nothing develops by then. I received a lot of responds to my choice of using a fuel injector to the standard carburetor that comes with it and have been told by other folks who fly around here that besides the slightly better fuel economy it helps under conditions of icing where some carbs may freeze. I probably won't be flying very low most of the time as I have the Appalachian Mountains surrounding Knoxville, TN and I need to scale over the Cumberlands from here in Tennessee to get to Ohio where my family is from, so the freezing issues at 9000 to 10000 ft. do concern me. Thanks again for your response, as all the info I can gather is beneficial.

Comment by Phill Barnes on February 16, 2010 at 3:31am

Hi Jay
Just a few updates about Jabiru. Stephen Smith on this site has purchased the Rotec TBI-40 injection system so it may be worth talking to him about the quality and functionality of this item. Here in Australia, there is a man by the name of Wayne Johns who is a Jabiru guru. He has developed an electronic fuel injection system for the Jab engines and is in high regard with Jabiru Aircraft company. I can't fin an email address for him at the moment but his phone number including country code is 618 8556 5562 . The word from the Jabiru staff is that Rod Stiff is also contemplating designing an electronic fuel injection system. I will ask him about it next time I visit the factory. Worth keeping an ear to the ground with the jab web site if that is the track that you would like to head down.

Regards
Phill

Comment by Phillip Owens on February 8, 2010 at 3:34pm

Dear jay, Congratulations on your decision to swithch to the 3300 jabiru, I am runing the 5100 8 Cyl on my 801 and I can tell you it is as smooth as glass. I am not sure you would be making a good choice in changing from the Altitude compensating carbys that come with the jabiru and going to the injection system, it adds complexity to the system as well as cost and currently I don't know who would be able to give you the required specifications on ratios and timing that would match. It would be a shame to blow up such a nice engine by changing to a system not designed for the engine. Consider the engine was designed to be easy to operate and repair in the outback of Australia, thats deep in the bush, it also has a proven track recors with the Bings so perhaps the change would only be a source of unnecessary expense. just food for thought.

Comment by Richard Simmons on January 28, 2010 at 11:50am

Hello Jay,

I live close as well. I live in Murfreesboro, 25 miles from Jabiru!I wound up using a Jabiru myself. Well proven and simple in design. Convenient as well as good folks!

Comment by Jacob on January 28, 2010 at 6:03am

Hi Jay,

Personally I don't why you would have any less reliability with a carby engine especially one that controls the mixture for you. I personally admire the simplicity of them especially on aircraft. The only real downsides are icing and not as good fuel economy. Although the rotec injection seems like a pretty good value system although still not a true multipoint injection system from what I could see (only had a quick look at the website) and is still would suffer from icing. Those ul engines look like a pretty good setup on the fly with gus website although they don't have a 6 pot one yet they are true efi which is a great but also introduces more potential for problems. Oh yeah lycoming are just releasing a new lsa efi engine too bet it's not cheap though. Definately no lack in choice thats for sure. Good Luck!

Comment by Sebastien Heintz on January 27, 2010 at 4:55pm

Good choice. We've flying with the Jabiru 3300 engine in both our Zodiac XL and STOL CH 750 demo planes.

• ‹ Previous
• 1
• 2
• Next ›
• Page