Jabiru 3300, Mogas and .... wait, what?

[andrewp]

Hi Folks,

Good ol Sonex 618 has been running nicely, but over the last 18 months, we have been running over to the dark side and fixing up an elderly Cessna 182 from 1962 and living that adventure. The are good boring airplanes, but boy I surely wish Sonex made a 4 place airplane that we could take the kids everywhere in. Operating a certified airplane is a massive pain in the ass/arse.

Actually let me get off my topic for a moment:

We have two growing children and we like to go places as a family. Aviation shouldn't be a separating activity, it should be inclusive. We have been into the SFRA in DC, down to the coast, up to Hershey PA and of course locally for BBQ. Aviation takes on a whole other dimension when you can do it with everyone and it changes what you fly to and what you do when you get there.

At the risk of John Monnett personally coming down to NC and punching me in the face (I would deserve it, not just for this), if Sonex were to (say) come up with a trigear four place with a nice V tail that hung a UL Power engine with 160-200hp and awesome FADEC on the front, I would dump the 182 in a big ditch and go build that. It doesn't have to do what a 182 does, but I can tell you, I would do it. I LOVE my Sonex dearly and giggle like a school girl when I fly it (particularly after flying the 182) and just wish it fitted the kids so I didn't have to lower myself to be seen in a Cessna. It is fun to yank and bank, but it is sure fun to go places and see stuff as well, and it is nowhere near as much fun by yourself. Now this is a bit of a departure from the normal Sonex mission and all that, but I don't care. I don't want to build an RV, I like Sonex. I don't have 200K to spend on an RV-10. So, if you are like me and probably mentally ill, feel free to send me a message and we can form a committee and then make a working group and then maybe write up some minutes, because a 4 place is not really a "sport aircraft". Regardless, I am very passionate on this topic. I tell you who is more, is the lady who lets me live at her place. Like all pilots, it is all about ME ME ME. I mean us. Ok, got that off my chest. Moving along.

Ok, onto the actual topic:

The 182 has a lowish compression o-470 engine. We have been running non-ethanol mogas in it and apart from the issue getting it into the airplane, it has been delightful. For the type of trips we do, it means a lot of the time we can run off mogas. Hell it can run off normal unleaded stuff and be happy, although we use the higher octane stuff. The auto fuel STC sticker of course makes the engine work.

The Sonex I have been loathe to try anything that isn't 100LL. I had to wrap my gascolator and wrap the exhaust a lot to stop fuel vaporization on 100LL. I know one gentleman who did some nice stuff with shielding and directing flow who ran mogas with a 3300, but I am pretty sure if I ran it in my current configuration, there would be a lot of burbling. I finally just paid attention to the burp tube thing and I understand what folk are on about there... now.

Anyway, I am interested in folk to do run off mogas in the Jab 3300 (premium ul of course) and/or aerovee, what steps they took to prevent vaporization and the general experience. If folk are running with that evil ethanol in there too, love to hear how badly that is going. I have to have something to do with the next decade after the 182 is finally fixed up and I am waiting for the end of time for Sonex to bring out a four place airplane (NOT).

John, you don't even have to call me. I will just tell go look at myself in the hall of mirrors and tell myself off. Doesn't stop me from wishing.

Cheers,

Andrew
Sonex #618 N618PE
Cessna 182E 1962 N3070Y

[Daviator]

Andrew, have you thought about a twin Aerovee 4 place airplane? John would love to be able to sell 2 engines to every builder, and then he just might accept your 4 place challenge and not hit you over the head.

[Concorde]

Where in NC ?

[andrewp]

Andrew, have you thought about a twin Aerovee 4 place airplane? John would love to be able to sell 2 engines to every builder, and then he just might accept your 4 place challenge and not hit you over the head.

GENIUS! Man, you are on the committee!

I guess after that we can make a four engined sport plane, with a turbo option? Now there is a product line...

[andrewp]

Where in NC ?

We sully the ramp at KHNZ (nominal home of the Sonex) and KLHZ. We live closer to KLHZ...

[ldmill]

Hi Andrew,
I exclusively run Mogas (premium) and live in central Iowa - where it gets bloody hot at times... I ran the Aerocarb the first 130 hours and stumbled/burped more than I really care to admit. I insulated stuff - removed gascolator, directed cooler air onto carb to cool it, tried air deflectors to direct heat away from Aerocarb (carb sits right behind oil cooler), tried insulating exhaust pipes, went to a straight downhill fuel run from the tank to carb - darn near everything I could think of except burp tubes or a electric fuel pump and low pressure regulator.

I did investigate Avgas during that 130 hours as well- it wouldn't burp nearly as much - but would still do it occasionally when the engine compartment was seriously heat soaked. After looking at a lot of installs, I realized that my engine is very tightly cowled - even for a Jab3300. However - when fuel was $6 per gallon - I went back and focussed on a Mogas solution...

At 130 hours, I finally took drastic measures and bailed on the Aerocarb and went back to a fuel pump/Bing system since I still had them. For me - the problem resolved itself solved immediately. Not a single burp/hiccup since with mogas. I've got 57 hours after the change - the majority at elevated temperatures with lots of heat soak experiences- including more than 5 hours last week alone with temps 90f+ out here.

For me - it appears that the issue has finally been resolved.


Lorin

[vwglenn]

I would avoid anything with ethanol like the plague unless you fly your plane multiple times per week. It'll eat your fuel system from the inside out if it stays stagnant for any length of time.

[sonex1374]

Andrew,

I've been running 100LL and Autogas in my Sonex for the past 200 hrs. So far it's been working well. I usually run some mix of the two, based on what I last filled up with, but at times have run mostly 100LL or mostly autogas and haven't really noticed any difference in how the engine runs. The one problem I've had with burbs has been on a worst-case day, with mostly autogas in the tank, the plane left on the hot ramp all day getting heat soaked (6 hrs @ 100+ deg), then a really long ground taxi prior to departure (+10 min). I've only had the one incident, and the remainder of my flying has mostly been shorter duration (1-2 hr flights) with cooler temps (80-95 deg) and the plane coming out of the hangar (no heat soak from sitting in the sun). Under these conditions it has worked fine. I have a filter (no gascolator) and insulated all the fuel lines forward of the firewall.

I run premium auto gas, and I'm picky about where I get it. I do 4 tests to find a good fuel station, then stick with that one. 1) High-volume station. Fresh gas and lot's of turnover is important. 2) Sniff test. If the fuel smells skunky, I don't use it. Try smelling 100LL - it has very little smell to it. Then go to the super-discount gas station and smell that crap....skunky! 3) White paper towel test. Poor a small qty of fuel into the center of a clean white paper towel (3" dia circle) and let it evaporate. If it leaves a discoloration or ring, the fuel has additives that will deposit on the inside of your fuel system and carb. Shell and BP are notorious for this. Don't use it! 4) Ethanol test. I have a test kit from Lockwood aviation that uses a measured qty or water and fuel, then you can read the percentage of ethanol directly off the tester. It works well. I use 5% ethanol as my limit. Most gas stations will have less ethanol in their premium grade than the regular grade. I've found that if a particular station passes the first 3 tests it will likely pass the 4th as well.

The other thing I do is to shut down my engine by turning off the fuel valve at the tank rather than use the mags or the mixture to kill the engine. This purges the entire fuel line, flow meter, filter and aerocarb of fuel. That way there is much less exposure to any ethanol or other substance contained in the fuel that would otherwise just sit in the lines for long periods of time.

Having said all that, the price difference between 100LL and premium autogas in currently only about $1, so for the added peace of mind, 100LL is pretty cheap.

Jeff

[andrewp]

Thanks Jeff, that is excellent info. Price differential for non-ethanol gas here and on the field where the Cessna is is about $1.70. When you burn 13 per hour that adds up. Religiously test for ethanol in the way you describe.

Good to know you are doing it at all, I will ponder what I want to do.

[fastj22]

I almost exclusively run 100LL in my Sonex now. But when the price was real high, I did use premium auto gas. I noticed more burps and some detonation on climb out if leaned out. So suffering through the burps on take off and going full rich, it still runs pretty good. I did kill my Princeton Fuel probe with the ethanol though.