SonexBuilders.net

The biggest obstacle with putting a Jab3300 on your Onex is lack of support from Sonex firewall forward. Important for a first time builder, not so much with a seasoned builder.

Darren S wrote:The turbo aerovee is of course going to go thru it's teething pains and troubleshooting. Plus from what I understand the weight is going to be near or more than the jab 3300 (I need to double check this).

I don't really want to be the beta tester. The Sauer seem interesting but what about support and reliability?

To me the best value for power and weight is the 3300. Albeit a used one. I won't be buying a new one. I don't know why more onex builders haven't gone this route?? Am I missing something huge and obvious?? If so, please enlighten me:).

Sauers exists in hundreds of motorgliders (700+). They are certified engines. The "UL"s are the same engines, only non-certified. TBO of 1500 h. It is not comparable to GP/Aerovee/Revmaster, much better design and more HP at lower revs, double price as well.

Living in Europe, if support is an important issue, then Rotax, Sauer, ULPower and Jabiru is the way to go. Jabiru because they have been around for a while and there are many of them. But, Rotax rules here compared with any other (100HP) engine.

The Jabiru 3300 most be a bit longer than an Aerovee? If so there might be a problem with CG afterall, you may not be able to pull it far enough back? I don't know, but it's something to check.

I don't think the Jab3300 will be a problem fitting under the stock Onex cowl nor a CG issue. This is based on the universal cowl being used on the Sonex. Yes, you will probably have to mount it closer to the firewall like the Sonex, but its only an inch or two.
Personally, I don't like the Onex cowl. I think its too boxy and not very appealing. If I do build a Onex, I'll seriously consider fabricating my own or modifying the stock one. For what its worth, I also think the stock Sonex cowl is too boxy.

CG is an issue I'll need to keep an eye on. I wish there was someone out there who has mounted a Jab 3300 on the Onex. I'd love to hear their feed back. One trick the RV'ers do is to mount the battery in the tail. Easy enough to do....like I said, wish I could see one done.

None the less I have lots of building to do prior to this decision. As in the past, the answers are always out there in cyber land:). One step at a time.

In the past there has been a lot of chatter and some negative responses from owners I've talked to about various problems with the Jabiru 3300 to include CHTs. Have those been resolved with their current engines.

Tom Jones
ONEX Kit #133

CHTs are manageable, but seem to require some tweaking of the air dams to get them right. I spent the first half of my Phase1 getting them under control and evened out. Others have fits tuning the Aerocarb. The biggest problem lately with the Jabirus is the SB that requires you replace all the thru bolts on the case. This requires you split it. That has not made many owners very happy. Other than that, its a great engine for me so far. Smooth as silk, sips gas, sounds great.
But if you want chatter, get on the Rotax boards and read about all the SBs on them.

fastj22 wrote:CHTs are manageable, but seem to require some tweaking of the air dams to get them right. I spent the first half of my Phase1 getting them under control and evened out. Others have fits tuning the Aerocarb. The biggest problem lately with the Jabirus is the SB that requires you replace all the thru bolts on the case. This requires you split it. That has not made many owners very happy. Other than that, its a great engine for me so far. Smooth as silk, sips gas, sounds great.
But if you want chatter, get on the Rotax boards and read about all the SBs on them.

Maybe I should look more closely at the Jabiru 3300, but so far the Sauer 2400 is the most tempting. What do you mean "others have fits tuning the Aerocarb"?

Aero carb fits are not exclusive to the jabs. The aero carb is such a simple design, it is difficult to find the sweet spot on adjustments to meet a broad range of conditions. Several have abandoned it in frustration.
It's not a set and forget like the bing. But it provides you a lot more control on EGTs.
The non pressurized fuel system has produced the burps which is normally experienced at takeoff and will make your heart skip a beat.
I have a love/hate relationship with mine.

fastj22 wrote:Aero carb fits are not exclusive to the jabs. The aero carb is such a simple design, it is difficult to find the sweet spot on adjustments to meet a broad range of conditions. Several have abandoned it in frustration.

For a recent thread concerning the Aerocarb:

viewtopic.php?f=33&t=344&hilit=aerocarb


Dale Williams
N319WF @ 6J2
Myunn - "daughter of Cleanex"
120 HP - 3.0 Corvair
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