From: "Alpha" Subject: COZY: auto gas Date: Thu, 4 Nov 1999 11:06:14 -0500 Mr. Arlen Bell, Can you enlighten us on how the refineries make avgas and how the process differs from autogas? Why aren't we just getting a slightly more refined crud? Jim Brewer Albemarle, NC From: "Nat Puffer" Subject: Re: COZY: fuel/fuel tanks Date: Sun, 31 Oct 1999 12:56:38 -0600 Glenn, You should be aware that auto fuel has a higher vapor pressure (about twice as high) as avgas, and would vapor lock more easily at high altitudes. Also, auto fuel has more unsaturated cyclic compounds which tend to be more aggressive solvents. Regards, Nat PS: A builder whose job was to blend auto gas for Shell told me some time ago auto gas is used to work off by-products of refining which they could not otherwise sell. That is here-say. Don't know if it is true or not. ---------- From: Glenn Murray To: Cozy Cozy-builders Subject: COZY: fuel/fuel tanks Date: Saturday, October 31, 1998 1:30 PM hi all can you tell me if the lycoming 0-320 E2A (ex cherokee 140) will run OK on unleaded mogas,and will the unleaded fuel react to the saf-t-poxy that the tanks are make of? thanks Glenn Murray ( cozy classic 3 place flying brilliantly) From: Militch@aol.com Date: Mon, 1 Nov 1999 09:33:58 EST Subject: Re: COZY: fuel/fuel tanks In a message dated 10/31/99 7:34:49 PM, GlennMurray@currantbun.com wrote: >can you tell me if the lycoming 0-320 E2A (ex cherokee 140) will run OK on >unleaded mogas,and will the unleaded fuel react to the saf-t-poxy that the tanks > There are 320's flying that have been STC'd for mogas, so it's definitely possible. Regards Date: Wed, 03 Nov 1999 13:40:47 -0700 From: hrogers@slac.stanford.edu (Howard Rogers) Subject: Re: COZY: fuel/fuel tanks >>My EAA Chapter has been working on the tanks of an old Bellanca which had >>used auto gas for many years (aluminum tanks). It was eye-opening how much >>brown tarry crude had built up in them over the years. After we flushed them >>several times with MEK, and let the flushed liquid evaporate in a coffee can, >>we had 2" of tar-like goo in the can. >> Aside from the unknown chemistry of auto gas, I wouldn't want to >>have to >>clean this goo out of fiberglas tanks. I suppose if you fly a lot and drain >>your tanks when inactive, you could live with it. >> >>--Kent A Interesting that you would immediately draw the conclusion that auto fuel was the culprit. How clean were the tanks before auto fuel was first introduced? Is Auto fuel the only fuel that will precipitate out gummy crap if left to stand for too long? I ran approximately 1600 hours of auto fuel through my aluminum-tanked Grumman over a 10 year period. I overhauled the engine at TBO (plus a little), and the entire engine was beautiful inside (including the rubber parts). I was inside the fuel tanks, just before I sold it, and they were pristine and shiny inside. Amazing. -Howard Rogers A&P 2005148 From: SWrightFLY@aol.com Date: Thu, 4 Nov 1999 08:03:03 EST Subject: Re: COZY: fuel/fuel tanks In a message dated 11/3/99 2:48:48 PM Central Standard Time, hrogers@slac.stanford.edu writes: << Interesting that you would immediately draw the conclusion that auto fuel was the culprit. How clean were the tanks before auto fuel was first introduced? >> Ran auto fuel in my Varieze for 10 years with no problems and the tanks were perfectly clean. Steve Stagger EZ N700EZ Date: Thu, 04 Nov 1999 16:31:26 +0200 From: "Rego Burger" Subject: COZY: fuel/fuel tanks We are getting reports of some using auto fuel for 10 years with and without problems..... To get a better database one should specify : 1.) The type of fuel used. 2.) The type of epoxy used for the construction of the tanks... 3.) Goo or no goo per 50 hrs flying time. 4.) Tanks left full or empty overnight. Only then will one find the combination or pattern. :-) There are resins that are 100% fuel proof! Régo Burger RSA From: ArlenBell@aol.com Date: Thu, 4 Nov 1999 10:20:08 EST Subject: COZY: fuel/fuel tanks As a pre-bulder, I can't address the auto fuel/epoxy question yet. However, I'm enjoying the debate and gathering information. I CAN however address some of the issue. Nat's remark in a previous post is right on in the area of vapor pressure -- refineries DO dump a lot of "stuff" in the auto gas (and fuel oil) they have no other easy/cheap way of getting rid of. Obviously, heavier mole. wt. in the fuel oil and lighter stuff in the auto gas (most notably butane). This vaires by time of the year and the market for misc. fuels as well as the cracking/reform capabilities of the individual refinery. I won't even get into the issue of tanks not being completely emptied or cleaned between product changes -- or the inadvertent missing of things like kerosene and gasoline -- seen it too many time -- big problem when kerosene heaters blow up! I can speak with some authority on this as in a former life, I spent several years with a corporation [to be left unnamed] which owned two refineries in UT & NM along with about 500 gasoline stations. It's often amazing how well auto can burn-up a lot of stuff the refineries would otherwise flare (and not sell). Crud in the tank can come from a lot of places (I'm still interested in anyone who has good info. about how epoxies stand up to the full range of mineral solvents which CAN be present in auto gas). I think an important item that's getting lost is the vapor pressure unknown -- do you want to take a chance on filling up with butane (an who know what else) mixed in your gas? [No, it doesn't readily boil out of the gasoline like you may think -- sort of acts like CO2 in soda -- some just keeps coming out everytime the temp./pressure changes!] It's sorely tempting to run the cheaper gas -- maybe in an ultra light where it maybe the least of your concerns! -- but in a serious plane -- not for me! -- Arlen Bell From: "Nat Puffer" Subject: COZY: new info-mogas Date: Thu, 4 Nov 1999 13:08:02 -0600 Builders, Because of recent postings on auto fuel, I called the EAA to inquire about the extent of their STCs on auto gas. They obtained approvals for the Lycomings through 150hp, but not the 160 hp 0-320 or the 180 hp 0-360. They referred me to Peterson Aviation, in Nebraska. I called Peterson, and they said yes, they have the STCs on the 160 hp and 180 hp Lycomings. They said for factory builts, you have to purchase the rights for both the airframe and the engine. For homebuilts, not to worry. He said that they did not get any detonation on 91 octane rated auto fuel in the 180 hp Lycoming (detonation is a function of compression rating). When I asked about oxygenating additives (we have those in Arizona because of air quality), he said the additives MTBE and ETB are approved, but not ethyl alcohol (ethanol). He said the objection to ethanol was a materials compatibility problem with diaphragms, hoses, etc. He also suggested that vapor pressure could be a problem, which is the reason you need approval for the airframe as well, because the airframe (high vs low wing) determines the routing of the fuel lines and the susceptibility to vapor lock. I don't know how accurate this is, but he suggested you might lose the higher vapor pressure alcohol at altitude, which would reduce the octane rating and might cause detonation at lower altitude (I don't know if this has been proven). If we lose 100LL some day, we may have to switch to mogas whether we like it or not. So it is reassuring that some have used it for a long time with no problems. Best regards, Nat From: alwick@juno.com Date: Thu, 4 Nov 1999 18:09:22 -0800 Subject: Re: COZY: new info-mogas Good objective reporting Nat. Thanks for researching! 100LL sure is a pain in my c150. Too cold, fouled plugs. -al wick On Thu, 4 Nov 1999 13:08:02 -0600 "Nat Puffer" writes: > Builders, > Because of recent postings on auto fuel, I called the EAA to inquire about > the extent of their STCs on auto gas. SNIP ___________________________________________________________________ Get the Internet just the way you want it. Free software, free e-mail, and free Internet access for a month! Try Juno Web: http://dl.www.juno.com/dynoget/tagj. From: "Nat Puffer" Subject: Re: COZY: Re: fuel/fuel tanks Date: Wed, 3 Nov 1999 17:23:53 -0600 Builders, I think we are talking about apples and oranges here. The question wasn't whether car gas dissolves aluminum tanks. The question was whether it dissolves epoxy tanks. After using auto gas in my Varieze for a little over a year, I had an engine failure on takeoff. There was about a tablespoon of gunk in the carburetor bowl. That is when I decided to use avgas, and I have used it for 20 years now with no engine failures. Not all auto fuel has gunk in it, or will dissolve epoxy. However, if you fly all over the country, you may have the same experience I did. Fortunately, I was on a runway about 6000 ft. long, so I was able to stop before rotation. I don't like to live dangerously, and I hope to live to fly until I'm 100. But everyone has different goals. You can either go by the experience of others, or by your own. Regards, Nat > From: LCDR James D. Newman > To: Canards - 'R' - Us > Subject: COZY: Re: fuel/fuel tanks > Date: Wednesday, November 03, 1999 5:57 PM > > Date: Wed, 03 Nov 1999 15:57:43 -0800 From: "LCDR James D. Newman" Subject: COZY: Re: fuel/fuel tanks Hi Kent and Howard, >> Kent Ashton wrote: > >>My EAA Chapter has been working on the tanks of an old Bellanca which had used auto gas for many > years (aluminum tanks). It was eye-opening how much brown tarry crude had built up in them over > the years. After we flushed them several times with MEK, and let the flushed liquid evaporate in > a coffee can, we had 2" of tar-like goo in the can. Aside from the unknown chemistry of auto gas, > I wouldn't want to have to clean this goo out of fiberglas tanks. I suppose if you fly a lot and > drain your tanks when inactive, you could live with it. > Howard Rogers wrote: > Interesting that you would immediately draw the conclusion that auto fuel was the culprit. How > clean were the tanks before auto fuel was first introduced? Is Auto fuel the only fuel that will > precipitate out gummy crap if left to stand for too long? I ran approximately 1600 hours of auto > fuel through my aluminum-tanked Grumman over a 10 year period. I overhauled the engine at TBO > (plus a little), and the entire engine was beautiful inside (including the rubber parts). I was > inside the fuel tanks, just before I sold it, and they were pristine and shiny inside. I ran 5 years on car gas in my Cessna 150, then rebuilt the engine myself. Engine looked great, so did the tanks. Could the "tarry crude" Kent talks about be a tank sealant that some mfg. slosh their tanks with? Date: Thu, 04 Nov 1999 09:17:18 -0700 From: hrogers@slac.stanford.edu (Howard Rogers) Subject: Re: COZY: Re: fuel/fuel tanks Nat wrote: >There was about a tablespoon of >gunk in the carburetor bowl. Nat, did you have that "gunk" analysed? >That is when I decided to use avgas, and I >have used it for 20 years now with no engine failures. Several years ago, Chevron spent about $17000 on me to replace my engine, after they sold me some contaminated fuel (along with a lot of other folks here in Northern California). I have a friend with a Lancair 360 who is going through the exact same thing with Texaco right now. > Not all auto fuel >has gunk in it, or will dissolve epoxy. However, if you fly all over the >country, you may have the same experience I did. ...Or the same experience I did, with Avgas. When I fly all over the place, I burn whatever I can find at the field, and that usually doesn't include auto fuel. If I'm not mistaken, there is more toluene in avgas than in auto fuel, and it is a potential "disolver". Apparently, Saf-T-Poxy, EZ-Poxy et al seems to be adequately resistant to Toluene, in spite of itself. >You can either go by the experience of >others, or by your own. I guess that's what we are both doing. I saved about $16,000 on fuel costs over ten years by burning auto fuel, though this was only one of two motives for doing so. The other was that it was a much closer match to my engine's requirements than was 100LL. Heck, my Tomahawk's O-235 L2C, which was designed to run on 100LL, couldn't run much more than 20 hours without lead-fouling plugs, regardless of my efforts at ground-leaning, special plugs, etc. etc. I used a first class pump with dual filters (including a water-removing filter), grounding strap, Halon, just like the big boys, and never had one speck of crud in any filter, carb bowl, or sump for ten years and 1600 hours of auto fuel use. That is MY experience. YMMV -Howard Rogers A&P 2005148 Date: Thu, 04 Nov 1999 11:44:53 -0600 From: "Tom Brusehaver" Subject: Re: COZY: Re: fuel/fuel tanks > Nat wrote: > >That is when I decided to use avgas, and I > >have used it for 20 years now with no engine failures. Marv Getten, the guy who fly's the Flea that has been in all the magazines recently (cover of experimenter). He normally was burning auto fuel, but to get to OSH this year, he had to buy AvGas. He siad that the RPM was about 150 or more lower on avgas than on auto fuel. He asked a couple people about it, and for him and the engine he has (C-90 I think), the valve timing is such that the auto fuel burns quicker, and provides the power he needs while the valves are closed, but the avgas burns slower, so part of the energy was going right out the exhaust. I suspect the timing is different on the O-360's, so it shouldn't be an issue? From: SWrightFLY@aol.com Date: Thu, 4 Nov 1999 14:37:35 EST Subject: Re: COZY: Re: fuel/fuel tanks In a message dated 11/4/99 10:20:30 AM Central Standard Time, hrogers@slac.stanford.edu writes: << Apparently, Saf-T-Poxy, EZ-Poxy et al seems to be adequately resistant to Toluene, in spite of itself. >> I find this statement accurate for the Saf-T-Poxy tanks in my Varieze. Saf-T-Poxy (and I believe the current EZ-Poxy is the same stuff) had just come on the market and approved by Burt. I was very careful to mix the resin/epoxy exactly with an accurate scale and then mix each batch thoroughly for 4 min. before I did the inside lay-ups for the tanks. Then I coated (brushed pure epoxy) the tanks with about 5 coats of epoxy allowing each coat to "tack" before applying the next coat. This was recommended by Gary Hunter (we were friends ....long ago in Houston) as I built the tanks way back in 1979 or so. Thanks Gary......time proved you correct. I did the same thing last year as I glassed the inside of the Stagger EZ tanks. The big question I now have is .......Should I burn auto fuel in my new XP-O360 after it is broken in with Av-gas? Comments please. Steve Wright Stagger EZ N700EZ Date: Thu, 04 Nov 1999 14:43:38 -0500 From: Paul Krasa Subject: Re: COZY: Re: fuel/fuel tanks snip good, bad or indifferent, I am burning 93 octane Amaco Ultimate in my Long Ez. I was cleaning plugs after every other flight because I of lead fouling. I got sick of cleaning plugs real quick. I have it on good authority that tanks made of Ez-Poxy will stand up to autogas. I keep a close eye on my tanks and pull my finger screen, and check the gas collator every 25 hours, and I plan on checking the inside of the carb bowl every 100 hours. My choice to run autofuel is not about money. The engine simply runs better on it. Paul Long EZ 214LP Date: Thu, 04 Nov 1999 17:05:47 -0600 From: David Domeier Subject: Re: COZY: Re: fuel/fuel tanks Howard, re "The other was that it was a much closer match to my engine's requirements than was 100LL. Heck, my Tomahawk's O-235 L2C, which was designed to run on 100LL, couldn't run much more than 20 hours without lead-fouling plugs, regardless of my efforts at ground-leaning, special plugs, etc. etc." The STC re auto fuel useage says that the 0-235-L2C has to be modified for 80 octane fuel. How is that accomplished? It is interesting that there are no 0-360's (Lycoming or Continental) on the EAA STC list. I guess that has to do with the compression of the engines...looks like anything running at or above 8.5:1 is not suitable for auto gas. dd Date: Thu, 04 Nov 1999 16:56:53 -0800 From: "J. D. Newman" Subject: COZY: Re: fuel/fuel tanks Hi All, I read, once upon a time long ago, in a prominent publication (can't remember at this moment), that if you mix 1/3 avgas with 2/3 auto gas (and try to maintain that ratio), the avgas basically takes care of the vapor lock and freezing concerns of using auto gas, increases the octane of the auto gas slightly and helps with the engine materials compatibility issues. And the auto gas takes care of some of the avgas issues (runs better, excess lead). I tried this in my C-150 - worked well. Another point the article made was to make sure you know where the auto gas comes from, get to know the owner of the gas station, that it is not laced with other things that shouldn't be, and to use a good quality auto gas. Also, it's too much toluene in the gas that can dissolve resins (I don't know how much). Since then, auto gas has got even better. And someday, we will ONLY have auto gas (including diesel), and jet fuel, available. That's one of the many reasons I'm using the 3.3 ltr Subaru (besides the fact that it was designed for aircraft in the early 80's). [I'm talking about what I'm doing and am NOT recommending you do the same.] Infinity's Forever, JD Date: Thu, 04 Nov 1999 20:00:47 -0500 From: bil kleb Subject: Re: COZY: Re: fuel/fuel tanks David Domeier wrote: > > It is interesting that there are no 0-360's (Lycoming or > Continental) on the EAA STC list. take a look at the "other" big autofuel stc producer: http://www.webworksltd.com/WebPub/PetersenAviation/PetersenAviation.html > I guess that has to do with the compression of the engines...looks like > anything running at or above 8.5:1 is not suitable for auto gas. the higher compression just means that you have to use 91 octane or above. -- bil From: cdenk@ix.netcom.com Date: Wed, 3 Nov 1999 21:55:15 -0500 (EST) Subject: Re: COZY: Re: fuel/fuel tanks - Auto fuel FIrst let me say: I'm not taking a stand on auto or avgas for airplanes. I don't know where you all buy your auto fuel, I have had my own 150 gallon tank at home for close to 30 years. Always had bought from reputable suppliers. Never fill a tank shortly after the tank has been filled, Never had an issue with fuel quality. Fuel is fresh from supplier, but the lawn mowers and chain saw only get filled when used, nothing added or drained for winter. The Ford Bronco's are notorious for fuel tanks rusting out around 8 years (the current 96 was coated with Deltron within a week of delivery), as a result I have had to replace several tanks at 8 years. The ones that came off were clean except for rust from the outside in. The problem is the heavy steel skid pan and tank aren't painted properly. P.S. the 55 gal. diesel fuel tank gets washed out and refilled every other year. All I can say is garbage in garbage out From: ArlenBell@aol.com Date: Thu, 4 Nov 1999 15:46:47 EST Subject: COZY:Auto Gas crud?" Well, I'm glad you aren't asking for a lot! First, I'd recommend everyone interested in this subject read the information available at: http://www:purvisbros.com/avtech.htm Print out the pages and read them thoroughly. I'm glad to hear that many of you have had good experience with autogas -- the alternative is not good. As far as how avgas differs from autogas -- not to get too technical: The initial process is VERY similar. After that, it get complicated. Avgas has a narrower spec. range which it must meet and for good reasons. You can get the specs. and read them if you wish: ASTM D910. In actuality, refineries producing avgas have to spend more time on getting the specs right because they are likely to be tested by an independent lab. Auto gas has much looser specs. and refineries can and do both leave a lot of other distillate materials in the product (because of the wider allowable range of distillate temperatures) and "pump" other products back in (i.e. butanes, etc) if they don't have a need of capability to further process these HC's [hydrocarbons]. It is quite possible to get auto gas that is fresh, clean, and contains less than the "allowable" misc. HC's. However, there is far less certainty of this than getting avgas through the avgas "supply chain". The potential problem of mixed fuels I referred to previously is greater with auto gas as the tankers have several compartments which may be used for different products depending upon the station's order. Avgas is more often trucked in designated tankers (in my experience). In short, the production and distribution of auto gas is a lot less stringent that avgas. The EAA fuel page seems to promote auto gas http://www.eaa.org/education/fuel/gasoline.html However, I think it's missing the point of QUALITY CONTROL. Hope we can leave this topic soon! -- Arlen Bell Date: Mon, 08 Nov 1999 12:12:14 -0500 Subject: COZY: mogas test samples From: "Paul Comte" I think it is important to keep focus on one point raised in this thread. It is likely that a fuel distiller may elect to include impurities and occasionally "foreign" substances may be included by accident. To be more accurate, the fuel in the "soak" tests would need to be changed as often as the fuel in the tank of a working aircraft. That said, I do believe that a properly constructed epoxy/foam fuel tank will be reliable and within the risks I am willing to accept. Paul Comte Milwaukee, WI >At 05:03 PM 11/5/99 -0600, David Domeier wrote: >Nat, > > I've had some scrap pieces of my fuel tank bulkheads in a jar of >100LL since June of '96....no change in the the foam or epoxy to date. > > Half of those same pieces are now in a jar of 93 octane car gas. If >the avgas world comes to an end, I hope to know if this stuff will >dissolve my tanks. > >dd >