Replies to This Discussion

Permalink Reply by Tracy Buttles on January 29, 2013 at 4:52pm

I have used it ,the temps ahve remained the same but it just ran sooty out the pipe

 got the hole belly dirty and you could see a fine trail of soot from the ground as I had another guy fly it ,

mixing  would be an option .I tied it for a little while ,it helped a bit on the soot

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Permalink Reply by Dr. Edward L. Olds III on January 29, 2013 at 10:33pm

Tracy,

Thanks for the info.  I'm wondering what caused the difference in exhaust deposits?  I'll be interested in hearing other accounts.  Hopefully, others have some experience.

Ed

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Permalink Reply by Randy Ferri on January 29, 2013 at 11:20pm

I have 740 hours on my Jab 3300 and have used 91 octane 95% of the time (some times on trips 100LL is the only fuel available) and have no problems with it.  I don't know why someone would want to run all that lead through there engine if unleaded is available.

 

Randy

 

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Permalink Reply by Dr. Edward L. Olds III on January 30, 2013 at 11:55am

Randy,

Thanks for the comments.  Our airport has 91 octane, no lead, no alcohol at a dollar less than 100LL.  The cost of flying would certainly be a bit better.

Ed

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Permalink Reply by Thomas Makibbin on January 30, 2013 at 7:36am

I also use it on occasion. Normally on long trips where I know that I am going to use it all up.  I don't like keeping it just sitting in the tanks, but operationally I didn't make much difference.

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Permalink Reply by Dr. Edward L. Olds III on January 30, 2013 at 11:59am

Tom,

Thanks for the comments.  I liked your golf pictures!  My ancestors came from Upper Dauphin County, around Millersburg.  Someday, I'll fly there, I hope.

Ed

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Permalink Reply by Bob McDonald on January 30, 2013 at 7:37am

Ed

Put a nice chrome exhaust extension on the pipe extending it a couple inches and flipping it downward away from the belly. Castrol Super Clean and lots of soapy water wipes the belly clean in nothing flat. I had an outside air temp probe for my D180 mounted 1/2 way back on the bottom of the fuselage belly. It did not work well located there because of the exhaust flow hugging the belly skin giving false readings... now located inside the rear fuselage. It was hard to believe the exhaust would hug the airframe slipstream that tight.

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Permalink Reply by John Austin on January 30, 2013 at 10:25am

Bob,

Ditto on the exhaust extension ... worked great for me! After the picture below, I trimmed the downturn pretty much flush with the straight portion of the pipe and it still works just as well.

There seems to be a lot of reports on the 'net that Castrol Super Clean will etch aluminum. I supposed it's no problem if thoroughly rinsed off, but if one gets it back in seams and places where it can't be rinsed - might cause corrosion? I have no experience with it, but just noticed a lot of comments when researching it.

Simple Green has the same problem, but "Extreme Simple Green" is specifically formulated to be safe for aluminum, so that's what I use.

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Permalink Reply by Dr. Edward L. Olds III on January 30, 2013 at 12:04pm

John,

Am I to gather that you are using 91 octane fuel?  Or have you just reverted to high school and love cool exhaust pipes?

Ed

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Permalink Reply by John Austin on January 30, 2013 at 12:56pm

Hey, I always loved cool exhaust pipes ... or at least, how they sound! (Doesn't that 6 cyl Jab sound great?)

No, I've always run 100LL. I store fuel in my hangar at the farm airstrip, so I feel most comfortable with 100LL as apparently it can sit around for extended periods of time and remain stable. (Although with the 750, I've already run through about 500 gal since July, so with my storage tank only holding 300 gallons, it's staying pretty fresh right now!) To me, it also seems most convenient since I absolutely know what I'm burning in the engine. We don't have mogas at our local airport, so if I went the unleaded route, I'd have to buy it from gas stations and test for ethanol, etc. (You can't trust the "pure gas/no ethanol" advertising!)

I follow the Jabiru Engines group on Yahoo - as I recall, I've seen conflicting reports? Some claim great reliability and longevity from running the 100LL, claiming it's best for the valves, etc., while others say the "cleaner" unleaded prevents deposits, etc. As I understand it, there's very little lead (relative to yesteryears) in 100LL, anyway. I've always seen a little sooty exhaust deposit on my 206/IO-540 that I flew for years and a little with the Jab 3300 - nothing that a little cleaner wouldn't remove. If you're getting a lot of soot, could it be you're running a bit rich? I'm calculating-out at about 5 - 5.5 gal/hr with the Jab 3300 and 100LL. However, the exhaust extension and redirection eliminated deposits altogether - just needs a few inches and turned away from the belly, as Bob suggests.

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Permalink Reply by Dr. Edward L. Olds III on January 30, 2013 at 3:15pm

John,

This is a 2nd pass at a reply, something happened and when I sent it the first time, I lost most of the message?  

I used to tank some fuel at our farm strip, but have stopped because of worries about the tank being contaminated.  I am now fueling at the airport for fear of problems.

I think my engine is running very well, but I'm seeing fuel flow rates of 9 gals/hour on my Dynon.  I may need to recalibrate my K factor on the sensor or I may have a problem with venting or uncoordinated (skidding) flight.  I'm going to fill the tanks, fly an hour and then refill and check the burn.  That will have to wait because we are getting snow and 35 mph winds today.

Did you get my question about the rivet line in your oil cooling duct that you built?

Ed

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Permalink Reply by John Austin on January 30, 2013 at 5:02pm

Ed,

I built my 100LL tank/trailer by buying a 300 gal. farm fuel tank at the local farmer's cooperative. The new tanks were steam cleaned and sealed during manufacture, so they weren't a problem as far as contamination. I buy my 100LL at the local airport, which has above-ground tanks, so no water problem there. I keep the tank/trailer in my hangar and have a fuel filter on the pump output ... never had a drop of water in 20 yrs! I checked my gascolator screen at the 100 hr check the other day and it was absolutely clean, too. So, apparently no contamination problems!

You're on the right track - just do a few runs with a known quantity of fuel and calculate your burn rate/hr. Of course, 9/hr would be waaaay too rich.

As far as the oil cooler duct, the rivet line is there - it's just the rivet line isn't at the very lowest point on the tubular manifold, it's a little on the backside from the camera's perspective. Enlarge that picture you referred to quite a bit and you'll see the rivet heads poking up!

John

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