The problem with pump gas is that even with advertised free fuel one of two issues can arise:
1. Even ethanol-free pump gas can have detergents and additives that can have unexpected reactions with tank sealants and resins. 2. Many stations don’t have a separate manifold for ethanol-free so when you select it you still get pumped a gallon or more of ethanol laden gas before the manifold is cleared and the ethanol free is delivered to the nozzle. Only use mogas from an airport or station where there is no chance of mixing or contamination from other fuels. And even then test it with a test jar. Adam On Sat, Dec 6, 2025 at 10:53 AM Richard Kaczmarek via KRnet < [email protected]> wrote: > If you want to be able to run the actual car gas the tanks should have 2 > to 3 coats of Rhino 9700. It is an epoxy but has a Novolac backbone which > stops the effects of alcohol on epoxy. I have been using it for many years > from my days of building Lancair's and the 2 KR2's I completed. Neat thing > about 9700 is it is also a structural resin. It does enter B stage very > quickly even on cool days. > > Richard Kaczmarek > > On Sat, Dec 6, 2025, 10:33 AM Joe Horton via KRnet <[email protected]> > wrote: > >> Good Morning Folks, >> I am sharing this story again as a warning to anyone with epoxy >> tanks. >> On the way back from the gathering in Tennessee I think in 2011, I chased >> the cold front home all day with landing multiple times to wait for it to >> move ahead of me. I ended up landing somewhere south of Harrisburg PA. >> about 10 min after the FBO closed and they had no self serve. A local took >> me to a sonoco and I got 5 gal of 93 oct. (ya know the NAS Car racing >> fuel) and put in the header tank with several galllons of 100LL that was >> still in the tank. I flew for another 50 miles or so and had to call it for >> the night 50 miles from home. Left early the next morning and got home and >> to work before 7 am. I think that I flew again on maybe Wednesday or >> Thursday of the same week and noticed a bit of roughness in the engine >> operation. My memory is a bit foggy on the details of why I started to >> investigate but at somepoint that weekend I looked into the header tank and >> the erosion of the gel coat inside the tank was so evident. There was a >> line exactly where the fuel level had been when I put the 5 gal of Sunoco >> in. There were glass cloth fibers exposed. I drained and cut tank open and >> repaired it, but started to wonder about the epoxy that had erroded off the >> inside. I tore down all the intake and aerocarb and found a coating of the >> epoxy (vinyl ester) inside all the intake tubes and in the carb. I pulled >> heads but it appeared that the epoxy that may have gotten to the cobustion >> chamber burned with the fuel. What a mess. >> This was the first time that N357CJ had seen auto fuel in the 6 or 7 >> years of operations. >> I did try it at an airport in South Caolina at a Corvair college with non >> alcohol fuel and the engine ran so rough I drained it back out gave it to a >> local and filled up with 100LL. The plane never saw any auto fuel again. >> Mark L. has the plane now but to the best of my knowlege the wing tanks are >> still fine and the header tank has another 14 years or so on it Total of >> over 20 years now. >> My current build has aluminum tanks in the wings so that should not >> ever be an issue. The header tank was home built with just over 8 gal >> capacity and has had fuel in it for nearly 4 years now. I do look in every >> so often just for peace of mind. I for one will never take that risk again >> for the sake of roughly $2 a gallon difference. >> Like Larry always says "your results may vary" but I doubt it... >> Joe Horton >> Dr. Deans plane ready for inspection..N657CJ >> >> >> >> >> ------------------------------ >> *From: *Kayak <[email protected]> >> *To: *KRnet <[email protected]> >> *Cc: *Kayak <[email protected]> >> *Date: *Thursday, 4 December 2025 9:55 PM EST >> *Subject: *KRnet> ethanol - anyone running it >> >> is anyone here running ordinary e10 ethanol car gas? >> >> just throwing out the question because almost all cars (including old >> ones) are running on it, so it should be possible to accommodate it in an >> aircraft. another option is to have a tank with 100ll just for >> cristical flight phases like takeoff and climbout, and run the much cheaper >> car gas off the other tank for the cruise phase... >> >> >> >> -- >> KRnet mailing list >> [email protected] >> https://list.krnet.org/mailman/listinfo/krnet >> > -- > KRnet mailing list > [email protected] > https://list.krnet.org/mailman/listinfo/krnet >
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