Avgas vs Autogas

[Jim Lauden]

Re: Avgas vs Autogas

somo info picked up over the week end:
For those of you that have citco gas stations, as we do here in virginia, citco appears to be one of the few mogas suppliers not adding ethanol....so far...at least here in northern va. Someone from the eaa chapter also mentioned valero (?) as another non ethanol mogas source.
My 2 cents

i fly in eastern pa. And use auto fuel, checked with the manager of citgo station near me and he brought out the specs from his office and it showed the contents, enthanol was present. Was not stated on the pump at that time. I test.

[VictorBravo]

Re: Avgas vs Autogas

Buildup on the valve stem/guide from the 100LL was definitely the cause.

Does anyone else here use only avgas 100LL and Marvel Oil and not have these problems ?

[bobp]

Re: Avgas vs Autogas

Yes, I have flown 33939 over 260 hrs on 100LL and MM with no adverse affects.

Bob Pollard
Tomah Wi

[M Towsley]

Re: Avgas vs Autogas

John,

Regarding the dumping of 89 octane into all three storage tanks. It is NOT legal here. Though I know it happens, whether by mistake or by design, the State has a Weights and Measures Division who checks not only the pump is pumping the correct amount but also the octane level. There are a couple of stations we know that are under spec, we just don't buy fuel for any of our vehicles there.

[lfries]

Re: Avgas vs Autogas

I use 100LL. I run an extra 100RPM in cruise and have never had a
problem. MMO is not in its regular diet.

[fearofpavement]

Re: Avgas vs Autogas

Knew it was coming but when I went to our fuel supplier today to fill my cans with alcohol free gasoline I discovered that theirs has ethanol in it now. I discussed the dilemma with them to some extent and found out that there are govt incentives for them to distribute alcohol containing fuel. He at least made some phone calls for me and found one station that still had alcohol free fuel. So I went there and filled my cans. Don't know if that will still be a source in a few weeks when I need more. They would be happy to bring me a load of fuel without alcohol if I can take 4,500 gallons!!!

I can get avgas delivered for $4.75 but really hate to give the O-200 a steady diet of that. We only burn avgas in it when away from home. What to do?....

[PT13Pilot]

Re: Avgas vs Autogas

Does anyone else here use only avgas 100LL and Marvel Oil and not have these problems ?

Bill,
Been too busy to look on here much lately, but thought I'd jump in on this one. 100LL and MMO is the only thing I use in the old stuff, and some modern stuff too. The Stearman doesn't leave the chocks without MMO in it. And in the origional manual I have for the 680 Lyc, it is "approved" to use 68 octane for break in, and 73 octane continuously. Give me a couple shots of tequilla and I bet I can produce 73 octane! 250 hours and not one fouled plug, valve or any other problem. And all 9 compressions are still 77/80 or better.
Same thing with the small Continentals. Haven't seen a stuck valve with that combo either although I still think they are more heat coked oil related anyway. Although since I don't have my own at the moment, I don't know how religious some of my customers are with it. And I look at it this way, you can spend your time driving around, looking for gas without alcohol, spending money on kits to check for it, trying to "save money", dragging your gas cans around and hoping that crap that smells like "bad" gas coming out of the nozzle will keep your engine running long enough to get you over the trees. Or put 100LL that has stricter standards and known pros/cons and a little MMO if so inclined and go on with your life. And that crap they're selling and calling gas nowadays can start to go bad in a month or less, it's pumped up with additives that vent off quickly. How do I know? They guy that own's the T-Craft I rebuilt the wings on owns a company that makes fueling equipment, Husky Corporation. If you fill your car and there's a dog on the nozzle, he designed and builds them. He said he's constantly trying to find better/different materials to seal the handles, breakaways, and hoses that will withstand the stuff they sell today. He burns car gas in his only because the FBO folded, and there is no avgas at his airport.
Did some testing when we were spraying with a Bell 47 (Franklin powered), and an R-22 with 100LL and MMO with fantastic results in 2001-2003. Lot's of hours and good "test" data. Nothing scientific, just got tired of picking lead out of spark plugs, and other problems with 100LL alone. Flew them 30-50 hours a week and the change was dramatic after the MMO.
I need to get my point across in fewer words, my carpal tunnel's acting up again!
CJ

[Larry Lyons]

Re: Avgas vs Autogas

I have to add my 2 cents here, although they are far from scientific. As we have several gas powered engines, construction and marine, we are finding much less problems with old gas now days then 15 years ago. We have some equipment that runs only every 5 years or so. We used to dope it and still had trouble getting it to run. Now days we never see or smell "old gas" unless it is over ten years old. Used to dope my marine motors (not 2 cycle, no oil mix) every fall before winter, if they sat for 6 months only, no problem, but any longer and we did. Now days (for the last 5 or 8 years) we do not bother doping and have and are not seeing any problems. How ever one caveat, I do see a little problem with water. I just always change fuel filters in the spring and so far good luck. I am really enjoying this thread as it has addressed a lot of questions I had. Larry

[fearofpavement]

Re: Avgas vs Autogas

Speaking of old gas, I also have experience in this area as I have a lot of things that have engines in them. The only issue I usually have is if a fuel tank goes completely dry from sitting too long. Then there is usually a gummy mess in the carb (on small gravity feed engines) I just ran into this on Thursday with a wood chipper that I rarely use. We usually burn brush here but now, even though we are 50 miles from Atlanta we are considered to be in the metropolitan area and have a burn ban from May 1 to October 1. Usually I try to time my brush and tree work to be in the burn season but I had a pile of pine branches from some necessary clearing I did....Oh back to the subject. Anyway the chipper carb was gummed up but I just put some fresh gas in and worked the choke and throttle linkage back and forth a couple times to free them up and it ran fine.

I also have a few old cars and have gone years at a time without running them and have not experienced any problems with running them when I get around to digging them out of the garage and firing them up. I recently unburied a 1963 Falcon that has had only had 15 miles put on it in the last 8 years. It starts right up once i get the fuel into the carb.

All that to say that I personally have not experienced any issues with short shelf life on unleaded regular.

Regarding burning autofuel in the Tcraft. It is more than just a price issue. Even if avgas and unleaded auto gas were the same price I would still burn the auto fuel. (A few weeks ago the prices were within a few cents per gallon here, that spread has since widened)

Since we do our own annuals on the planes here, I see what the plugs look like. Usually the T-craft plugs need no attention other than verifying the gaps. ie, there are no deposits of "stuff" that has to be chipped and blasted off. On the engines burning avgas there is usually significant time spent chipping out the stuff around the base of the insulator and then sandblasting the rest of the crud off (which also shortens the service life of the plug since it takes some electrode material with it.) I haven't yet had to pull a cylinder off the Tcraft (about 600 hours on them) so can't verify the condition of the valve guides but we have had no low compression issues at all. So I feel that the 87 octane auto fuel (about 85 octane in old numbers) is much more suited for an engine that was designed to run on 73 octane or whatever than the 100LL available now. That LL is really a misnomer as it has many more times the lead that 80 octane fuel did.

So for now, I continue my quest to look for ethanol free auto fuel and if I can't find it anymore I guess I try the MMO? (that may be no more "approved" than ethanol fuel but probably better results).

[Pearson]

Re: Avgas vs Autogas

Bill,

How are you and your chemist friend doing on figuring out a way to remove the alcohol for car gas?

[Ragwing nut]

Re: Avgas vs Autogas

A lot of it has to do with the design of the combustion chamber. I have seen no other engine affected by 100LL like the small continentals. Other engines designed to run on 73 octane don't seem to be as suseptable (sp?) to the lead build up. Marvel will works but also increases the operating cost even more on top of the 100LL prices.

I don't have issues finding ethanol free gas here. Companies like BP, Shamrock, and Sinclair don't ethanol in any of their gas. I also never let auto fuel set in anything as it does deteriorate over time. Always store with 100LL in the tanks to prevent varnish build up in the carb from sitting.

[M Towsley]

Re: Avgas vs Autogas

This is from a post I made a couple of years ago:

The real reason there is ethanol in your fuel is for incentives. Their incentives are usually tax breaks for retailers to utilize ethanol in their fuels. This adds up to a rather large chunk of change if you think of the gallonage these retailers sell. My sources advised that BP (Amoco) Premium, not mid-grade, SHOULD be alcohol free. Testing I have done locally confirms this. However, I still run low-grade alcohol free fuel, as I don't want to spend twenty cents more per gallon.

Welcome to the world of ethanol.

[flyguy]

Re: Avgas vs Autogas

Ok, here goes, I'm going to run some material tests on ethanol-bearing auto gasoline. Various aluminum containers, epoxy coated objects, gaskets, O rings, ect. I will check for absorption and separation of moisture from the air also.
Suggestions for test items or materials appreciated. (or any other suggestions.)
Darryl

[dewhitaker]

Re: Avgas vs Autogas

Ok, I have a question. I have heard of adding a product called TCP to 100 LL to deal with the excess lead content. However, some of you have mentioned that you have had good results adding MMO to 100 LL. Why would this help? Have you actually seen inside the engine after time? In my earlier post, I showed pictures of the engine after being run almost exlusively on 100 LL for 300 hours, after a top overhaul. A picture is worth a thousand words, there can be no denying the 100 LL was the cause of the damage.

At this point we are still able to get mogas alcohol free, but I want to gather information for future reference. We were able to do another top overhaul on the engine to get it flying again, but I am saving my pennies to major the engine with new Millennium cylinders. 100 LL has 4 times the lead as the old 80 octane avgas, that is why I have been using a mixture of 1 to 4 in the engine since last year. Blending the mogas and 100 LL also helps to "stabilize" the mogas, which addresses some of the concerns there.

I am a firm believer in MMO, and if it is successfully helping with 100 LL, I would like more information. Keep the posts coming guys, this is an issue that is not going to go away, and we need good answers to keep these old vintage aircraft flying.

[flyguy]

Re: Avgas vs Autogas

TCP reduces the effects of lead on engines. That is what it was designed to do for automotive engines originally.
The (sole) distributor is not shipping it now due to problems with containers leaking in route. That is information from another site on line. There will be none available through 2009 at least and perhaps later.

As I said before, my engine at 200+ hours has that pink crap all over the tops of the pistons and the little pieces that chip off drop down into the bottom plugs every few hours of flight so I am searching for something that will help. No luck here because all the gas has 5% methanol, for smog, in it.

On the other hand, I know of one guy who has been burning that same gas in several airplanes for several years and claims to never have had any problems. So I figure I will run some tests on various materials. There is nothing quite like facts to get one's head on straight.
Darryl