Experimental Cub/ethanol fuel

I sure like the looks of Jay's 180 TCOW that is for sale on this site----not too far away either. Could it be set up to run ethanol fuel at any % blend I chose without a lot of paperwork and hassle other than what it actually would take to modify the carburetor and fuel system? Since I didn't have anything to do with building it, was wondering about the possibility.

Marty, Jay's airplane is experimental amateur built. You can do anything that you want to it as the owner. Take a look at his operation limitations for the full answer. What you are describing would be minor changes which you would sign off in the log book. You would need an A&P to do the annual condition inspection.

And you still would be 180Marty

Glenn

Thanks for the info Pete. Glenn it took me a few seconds to "get it". Good one.

That is one of the nicest ex supercub you will ever see.

Dean

The STC's prohibit ethanol, I believe because of detonation. However like others said, experimental is free to experiment. I only run E0 mogas in mine, 91 or higher.

Bugs, the ethanol doesn't cause detonation---it's very high octane. Here is a screen capture I took a few days ago of the E85 prices. Notice that this time of year it is in the 70 to 75% range for ethanol content since it is less volatile.

Bugs66 said:

The STC's prohibit ethanol, I believe because of detonation. However like others said, experimental is free to experiment. I only run E0 mogas in mine, 91 or higher.

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Actually Buggs, I believe that the reason that the STCs prohibit ethanol, is the simple fact that the STC holders have not tested ethanol fuel to the FAAs satisfaction. At the time, that the STC holders were going through their testing for their approvals, ethanol gasoline did not exist in the USA. So, there was no reason to test.

Thanks guys, not detonation maybe volatility is what I was thinking. Here are the reasons according to Peterson STC:

DO NOT burn fuel with ethanol in your airplane. Revert to 100LL if ethanol free gasoline cannot be found.

• Ethanol fuels can damage the rubber and aluminum components of your aircraft fuel system.
• Ethanol increases the volatility of fuel.
• Ethanol can absorb significant amounts of water in flight.
• Ethanol may vent off at altitude, reducing both range and octane.
• Ethanol has fewer BTUs than conventional gasoline, which further reduces range

More: http://www.autofuelstc.com/fuel_testing.phtml

Buggs points out the #1 (in my mind) reason for not using ethanol fuels and that is the stuff will turn many rubber parts to black goo. Many of us tried running it in our Nanchang CJ6's (9 cyl radials) with bad results all around. I have heard of guys "distilling" it by adding water then pouring off the fuel. This IMHO is a risky experiment at best and assumes that 100% of the alcohol will attach it's self to the water and settle out.

Long time ago had a pa22 160 hp, Always used cargas, avgas only on trips , and yes I was flying frequently. NEVER had any problem an cargas. The only sad person about it was my fbo couse of the cleanspark plugs he never had to work on

I probably have the most hours here flying with E mogas, though in a Rotax. Can't tell any difference, hot, cold, it flies normal, if a range/ power reduction happens its so minor its no biggie. It flies just like on the pure mogas I bulk tank at home. I haven't burned any Avgas in years/ thousands of hours. That's a pretty huge cost savings over time plus my auto plugs last forever.j

I have never worked on an aviation engine, so my experience is strictly pre computer controled automotive or powersport engines, so my following thoughts are only based on that (limited) experience.
Unless you are willing the change carb jets after switching blends, you will need fuel injection, and probably electronic fuel injection. E10 will be slightly leaner than E0, but close enough so rejeting is usually not required. E20-E30 will definitely require richer jets, but the rest of the fuel system can normally keep up without modification. E85 is run by some hotrodders where it is available. They will set up their car, or motorcycle, ect like the guys running straight alcohol. This requires alcohol carbs with larger passages, much richer jets, and high flow alcohol fuel systems. With automotive engines the compression ratio should be 9:1-9.5:1 with 92 octane E10, to maximize performance, compression ratios of around 12:1 are used with E85. My understanding is that aviation engines use lower compression because of a longer stroke, peak power at a lower RPM and of course the need for a larger safety margin against detonation. Another consideration is that alcohol burns cooler, to the point that alcohol dragsters can idle and run much longer than their gasoline powered counterparts, and I don't know how that would affect an air cooled aviation engine, good or bad. I have no experience working on electronic fuel injection, but I have run E85 in a Suburban with a 5.3 and the only thing I notice is that it burns more fuel, but costs less to fill compared to E10, about a wash. Its amazing to me that they can readily adjust to anything from E0 to E85.

Once you assure yourself the fuel system has nothing that will quickly deteriorate with alcohol exposure, I don't think you would have a problem running E10 Mogas, but as Rich Lean states, E-85 would require rejetting of the carb, which would then make it too rich to run E10 or Avgas. On a carburated engine, you would need to pick your fuel. The current configuration should be happy with E10, but without an electronic injection system like all E-85 automobiles, you might have some significant issues switching back and forth between E85 and E10. Even with a typical mechanical injection unit as used on most Lycomings, I would expect some significant difficulties switching back and forth between E85 and anything else. The default idle mixture is a manual setting, which would be problematic even if the injection system will run rich enough for E85.

I don't know if the electronic fuel injection system from EFII would be set up rich enough to use E85 and switch back and forth between E-85 and other fuels, but it might be worth giving the guys at EFII a call for a chat. They are pretty willing to work with their customers to build custom configurations, so that might be a good shot at setting it up as a multi-fuel engine. It's an interesting issue to work out.

-Cub Builder

Cub Builder said:

I don't know if the electronic fuel injection system from EFII would be set up rich enough to use E85 and switch back and forth between E-85 and other fuels, but it might be worth giving the guys at EFII a call for a chat. They are pretty willing to work with their customers to build custom configurations, so that might be a good shot at setting it up as a multi-fuel engine. It's an interesting issue to work out.

-Cub Builder

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Could be as easy as a richer tune, but if they're already maxing out injector duty cycle it should be as easy as larger injectors and a recalibrated tune. Though in my tuning experience (GM LS1/LS2 platforms) that's an iterative process. They are probably better than I was though.

The current configuration should be happy with E10, but without an electronic injection system like all E-85 automobiles, you might have some significant issues switching back and forth between E85 and E10.

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The way the Texas Skyways O470 UTS was set up was. Bigger jet in the carb for the 88% ethanol blend and when 100LL was used, you pulled the mixture out just like if you were at a high altitude airport. Probably wouldn't want a sloppy fitting mixture control in the carb. Here's some plugs out of a big Continental with a 180 hr's of E10. A friend took the pic. The other thing this friend found interesting was, all the cylinders checked out mid to high 70's for compression and look how uneven the plugs look. The top left was number five cylinder further from the carb.