Gami gas has arrived...

People have been running 180HP O-360s on 91 mogas for a while. Even if they had an issue but it wasn't being reported, in the aftermath of the 94UL issues some people should've said "me too".
And I doubt 91 mogas has better anti-detonation properties than 94UL.
 
I’ve got a headache from all this. Wake me up when this is all worked out. Until then, I’ll stick to 100LL cruising at peak egt at 65% above 5K in my O360A4M.
 
MajorTurbulence said:
I’ve got a headache from all this. Wake me up when this is all worked out. Until then, I’ll stick to 100LL cruising at peak egt at 65% above 5K in my O360A4M.
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Well, it will be settled in a few years. Just hope the answer is not to park a bunch of airplanes, including my Mooney.
 
Thought I would chime in with our experience running ethanol car gas in our C172 for close to 5 years….. important to note it has a GM V8 fuel injected engine but most of the fuel system is stock up to gascolator. We used different testing methods, such as borescopes, oil analysis, computer engine logging and analysis, 40 micron filter elements, ECT…

Our goal was to find a cheaper, mostly mass produced composite solution, more environmentally friendly solution than legacy engines ( engines are biggest culprit of high op costs), and had to use different fuel types so it could be flown anywhere. Thus, the V8 engine was low laying fruit. Ethanol was a concern from early design due to mostly ancient air frame fuel systems and materials. Without boring anyone with engineering mumbo jumbo, we were especially concerned about leaks forming which would be significantly more dangerous in our pressurized fuel system than stock gravity feed system, for obvious reasons.

The engine wasn’t an issue as it was designed for ethanol, and controlled by essentially a computer and software, which could figure out most efficient mixture (and spark delivery) regardless of fuel type used, or combo thereof. But the c172 tanks, lines, fittings, valves, ECT… were an issue. I had considerable experience in the marine sector where ethanol is a real problem due to humidity ambient conditions, as well as systems within a structure that took a beating compared to car suspensions. I also spoke to many experimental guys using car gas and read what I could.

There is a lot of misunderstanding and in many cases ignorant know it alls without any related first hand experience voicing opinions. So here’s what I can add to this topic from experience with our c172 over close to 5 years…. We did, and do, run different fuel types, including AVGAS, and tested all in flight testing, but majority of time run low octane ethanol car gas now, mostly due to lower cost and emissions.

First off, when initially converting or using ethanol gas realize that it’s a real cleaning solution and will break up contamination in all parts of the system, even those existing for decades. Really important to clean the older system prior and monitor filters to know when it’s absolutely clean. This could take several days or even weeks if the plane remains mostly static as opposed to fuel swishing around in flight. It took about 2 weeks before we were confident all existing junk was out of system.

Realize the seals such as o rings in most aircraft may be decades old and/or not compatible with ethanol, and will cause leaks. We left some of the original o rings in place as a control to see effects…. after bout 5 months the original wing tank sump began leaking, and was also replaced with a Viton material o rings. But nothing that big of a deal. Since log books didn’t say how long the o ring was there, there’s no reliable way of knowing its condition, so leak may have occurred with AVGAS, but I don’t believe any such failure would be a safety issue anywhere in a gravity fed or low pressure systems. However, in a high pressure system, even a small leak on the pressurized side could be significant hazard, to say the least. We basically put an updated o ring and seal kit together (along with new cap seals ) that was part of the conversion kit. Easy solution. It’s important to remember, if the certified o ring in 1950 was basic rubber, that still may be the same material used in new replacements…. So don’t assume every such part is modern when it comes to certified parts.

My post getting long so will just add this RE water…… true, ethanol absorbs water from air, but it’s not a huge sponge as some will have you believe. Aircraft have more protection from water contamination than cars or boats due to tank and low sump drains. For our c172, if all seals are good the only air contact to fuel is the small vent tube. I wouldn’t use ethanol gas in humid environments if you rarely fly, especially if not hangered , but we’re talking 4 months or more (but ethanol evaporates quick compared to other heavier octane additives and thus octane rating decreases, so long storage or old fuel bring other potential concerns…but agin, no big deal for most users). If ethanol is a concern, there’s always non-ethanol REC gas locally available which is over 90 octane and slightly more cost than regular gas…. We use this if we know the plane won’t be flying much for a a while and it’s readily available at near by gas stations next to our airport.

With anything, there’s trade offs ……ethanol fuel for us has the pros well outweighing the cons….. our now high performance c172 went from about $78/hr to less than $24hr to fly…… a few friends used it to train and take check rides in, earning their certificates at a fraction of the cost of renting or flying own c172 which cost being their biggest obstacle in getting their licenses. A couple of local CFI s are building time flying it to air shows and can’t believe the same vintage c172 rents for $175/hr at their school, and happy they are not burning lead.

I was asked to write a technical paper about our c172 testing with ethanol a ways back, but free time is scarce, but will post a link here if I do. To sum it up, the hype of airframe fuel systems vs ethanol is just that, hype, in most cases. We didn’t test ethanol with the original O-320 engine, but expect any issues could likewise be mitigated as many use car gas in such engines, especially air boats and experimentals. …. But I have no first hand experience so not qualified to comment. Leaded AVGAS days are numbered, and as FAA loves creating legacy monopolies regardless of cost to GA, approved fuels will further increase costs…. I expect to see STC’d fuels to be $2 more than AVGAS in most markets, and continue higher once AVGAS is phased out….again, another FAA sponsored monopoly. Further decreasing GA market size, and accelerating higher costs as demand dwindles with fewer innovators wanting to invest in viable solutions based on such market projections.

Sorry for longer than needed post.
 
AlphaPilotFlyer said:
majority of time run low octane ethanol car gas now,
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AlphaPilotFlyer said:
I wouldn’t use ethanol gas in humid environments if you rarely fly, especially if not hangered , but we’re talking 4 months or more (but ethanol evaporates quick compared to other heavier octane additives and thus octane rating decreases,
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AlphaPilotFlyer said:
Thought I would chime in with our experience running ethanol car gas
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There's a lot of difference between E10-E15 and pure ethanol.
AlphaPilotFlyer said:
just add this RE water…… true, ethanol absorbs water from air, but it’s not a huge sponge as some will have you believe.
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See my note above. My response to the discussion referred to posts about running 100% ethanol.
 
clarkmueller said:
Sadly, it really isn’t… It would be convenient for aircraft owners if a replacement were fully fungible. I sure hope it is. But at some point, it will become easy just to ban 100LL and throw the aircraft that burn it in the trash or have engine/fuel system retrofits of some sort for the owners/applications where it’s economically logical (probably not many). When the day arrives that the powers that be choose to do this, a bunch of us piston owners aren’t going to matter a hoot. Meanwhile, Mogas and UL94 have already solved the problem for the training environment. Fortunately, the piston aircraft owners that can afford it will be able to buy turboprops and jets, and burn 3x the fuel for the same mission. Yay for the environment!
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Where do you get Mogas without ethanol at an airport? I went to flyunleaded.com and found zero in Maryland and one in Virginia. Lugging 40 gallons from the parking lot doesn’t work for me, nor flying an hour out of the way to the nearest airport so, “…solved…” seems a bit much
 
mogas often available on airport for ground equipment and automobiles that stay on property..... you may need to bring gas can(s). At home airport we got a 12v farm pump that we pump fuel from SUV filling port to plane ... about 6 gal/min.
 
AlphaPilotFlyer said:
mogas often available on airport for ground equipment and automobiles that stay on property..... you may need to bring gas can(s). At home airport we got a 12v farm pump that we pump fuel from SUV filling port to plane ... about 6 gal/min.
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Not ethanol free
 
both. actually, at some....but ethanol gas often is just not advertised.
 
AlphaPilotFlyer said:
both. actually, at some....but ethanol gas often is just not advertised.
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Neither are anywhere near me. And the closest airport with mogas is more expensive than 100ll
 
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Racerx said:
One of the problems with ethanol is shelf life. And the inability to detect water. That plane on the ramp in the rain. Are you sure those gaskets are doing their job? Is that still ethanol or is it vodka?
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I think the biggest ethanol challenge, after materials compatibility and reduced range, is that the fuel can show no water at ambient temperature on the ground. But as you climb, the fuel cools, and water solubility drops. So THEN the water comes out of solution, and if you climb above the freezing level, even in summer, the water freezes, perhaps blocking the flow of fuel to the engine. Bad thing.

Paul
 
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Half Fast said:
The same reason the water in your car radiator doesn't separate and freeze in the winter. Bombay Sapphire is re-branded antifreeze.
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There's a reason tito's doesn't do distillery tours. They ship ethanol in by rail car.
 
PaulMillner said:
I think the biggest ethanol challenge, after materials compatibility and reduced range, is that the fuel can show no water at ambient temperature on the ground. But as you climb, the fuel cools, and water solubility drops. So THEN the water comes out of solution, and if you climb above the freezing level, even in summer, the water freezes, perhaps blocking the flow of fuel to the engine. Bad thing.

Paul
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I had something similar happen in a Rotax-powered light sport airplane whose owner was putting car gas in it, except it didn't happen until after I landed and subsequently tried to restart it when it came time to return to my home field.
 
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ethanol does increase chances of vapor lock. espey in non pressurized systems.... so if engine bay was still hot before restart, likely the culprit ..ways around that.
 
Domenick said:
Why doesn't the 53% volume of water in the Bombay Sapphire in my freezer separate and freeze?
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Your freezer isn't cold enough.
See: https://www.engineeringtoolbox.com/ethanol-water-d_989.html

Actually, fractional freezing (fractional distillation) is used to make eisbock, applejack and other beverages. The low concentrations from fermenting grain or fruit ethanol allows the water to freeze at a fairly high temperature (below 0 °C). After the ice is removed, the concentration of ethanol in the remaining beverage is increased. A lot of impurities are also left that would be removed during fractional distillation, so your hangover will be worse.
 
PaulMillner said:
I think the biggest ethanol challenge, after materials compatibility and reduced range, is that the fuel can show no water at ambient temperature on the ground. But as you climb, the fuel cools, and water solubility drops. So THEN the water comes out of solution, and if you climb above the freezing level, even in summer, the water freezes, perhaps blocking the flow of fuel to the engine. Bad thing.

Paul
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I think you are discussing ethanol in a hydrocarbon fuel?
 
Cap'n Jack said:
I think you are discussing ethanol in a hydrocarbon fuel?
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Yes. PaulMilner's original statement concerns ethanol in gasoline (not water), whether mogas or avgas, so we're talking low concentrations of ethanol in liquid hydrocarbons. I am still not convinced, but willing to be, that the water which may be dissolved in the ethanol in such a system would freeze out under GA conditions.

As a side note, my chest freezer may be cold enough to freeze a 40% v/v liquor. I'll try a bit, but for the current discussion I'm not sure it's relevant.
 
Domenick said:
Yes. PaulMilner's original statement concerns ethanol in gasoline (not water), whether mogas or avgas, so we're talking low concentrations of ethanol in liquid hydrocarbons. I am still not convinced, but willing to be, that the water which may be dissolved in the ethanol in such a system would freeze out under GA conditions.

As a side note, my chest freezer may be cold enough to freeze a 40% v/v liquor. I'll try a bit, but for the current discussion I'm not sure it's relevant.
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Wasn't the first loss of a 777 due to water freezing out of jet fuel which then clogged filters and starved the engine of fuel during close final? I probably have some of the details wrong. It was a British Airways flight, IIRC.
I'll grant that Jet-A != 100 LL, and a 777 flies much higher (read- much colder air) than nearly anything that burns 100 LL.
 
Cap'n Jack said:
Wasn't the first loss of a 777 due to water freezing out of jet fuel which then clogged filters and starved the engine of fuel during close final? I probably have some of the details wrong.
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Heat exchanger, not a filter, but you're close enough to call it correct. Later the subject of an airworthiness directive mandating a redesigned heat exchanger.

Nauga,
stopping for a cold one
 
Cap'n Jack said:
Wasn't the first loss of a 777 due to water freezing out of jet fuel which then clogged filters and starved the engine of fuel during close final? I probably have some of the details wrong. It was a British Airways flight, IIRC.
I'll grant that Jet-A != 100 LL, and a 777 flies much higher (read- much colder air) than nearly anything that burns 100 LL.
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It happened to me in a lowly C-172H with a takeoff engine failure using 80 Octane FBO fuel that was available in 1971. It was a bitterly cold (-15 degF) MN day that I took a warm club airplane just-refilled filled with fresh fuel from the FBO underground tank. I tear-dropped to force land downwind on a parallel runway at FCM, never getting above 200 ft or leaving the airport boundary. The gascolator was ice plugged with snow crystals that didn't appear to a casual fuel sample until more than a quart of fuel was drained. Details and my analysis were publicized in an EAA Sport Aviation article in December 86.
 
How long has it been since you could find grades of avgas other than 100LL while out and about flying? Not that it really has anything to do with GAMI.
 
Chrisgoesflying said:
I received this email from Piper on April 1st. Assuming it’s not an April’s fools prank, does it essentially say “don’t use anything else than 100LL in your Piper even if you have an STC for an alternative fuel.” ?

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It depends on the STC and the fuel. The common Petersen STCs are for running unleaded mogas having no ethanol. Many common GA engines don't need 100 octane, but run just fine on 87 or 92 octane mogas. O-320, O-360, etc. This fuel has been around for decades and doesn't have the problems of the new avgas replacement fuels. Some of these STCs are paperwork-only - no modifications needed - usually in high wing airplanes like the 172 that don't have a fuel pump. Others require modifications, since mogas can have higher vapor pressure than 100LL, which can cause problems with fuel pumps or fuel injection.
 
Dixiebluesky said:
How long has it been since you could find grades of avgas other than 100LL while out and about flying? Not that it really has anything to do with GAMI.
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About 8-10 years ago KAWO in Washington and KMAN in Idaho had 92 octane mogas pumps right next to the avgas. It was priced about 50 cents less than avgas per gallon.
 
Dixiebluesky said:
How long has it been since you could find grades of avgas other than 100LL while out and about flying? Not that it really has anything to do with GAMI.
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It's not hard to find other stuff. Right near me, without even looking, I know that HXF has mogas and 57C has Swift 94UL.
 
flyingcheesehead said:
It's not hard to find other stuff. Right near me, without even looking, I know that HXF has mogas and 57C has Swift 94UL.
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Looks like there all of three airports here in Florida selling UL94, and two with mogas. Not exactly easy to find. And only about 35 in the country are selling UL94. That’s, what, about 1% of airports?
 
flyingcheesehead said:
Huh. I thought they did last time I fueled there, but looking at Swift's map, they're no longer on it.
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I remember seeing it listed but it's been at least a year since I remember it gone. 94ul always seemed to be more than 100ll. Guntly had 94ul and may still....but I ain't landing there. I thought Racine had Mogas but that's not listed either.
 
Well I just meant 80/87 or the 100/130 grades, those may not be correct. It really has nothing to do with the gas situation of today, it was just curiosity.
 
Dixiebluesky said:
Well I just meant 80/87 or the 100/130 grades, those may not be correct. It really has nothing to do with the gas situation of today, it was just curiosity.
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IIRC, 80/87 is the same as "mogas" and 100/130 has not been around in a LONG time. I've been flying for 22 years and it was long gone back then.
 
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