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News from Lycoming on auto fuel use in IO/O-360

The story says "unleaded 93 AKI automotive gasoline conforming to either Euro Norm EN228 or ASTM D4814 will be the basis of this Lycoming specified fuel."

In Southern California, I've never seen anything higher than 91 octane mogas. Interesting how Lycoming has changed their position on this after all these years.
 
That's great now that most auto fuel has 10% ethanol in them. Chevron and Phillips seem to be holding the line on that around here but Shell has gone to ethanol in the last few months. Don
 
The story says mogas is OK with Lycoming, but the airframer has to approve it's use, too.
I've never seen 93 octane gas in northern Utah. Phillips has 92 and everyone else has 91 premium.

running 100LL for now,
Steve
 
Mogas

For years, mogas user have enjoyed added reliability with mogas, and like the auto industry, the absence of lead improved engine life.
We have used it since it was approved, and in the case of 4 different engines, performance, economy, and reliability has significantly improved. The last experience was with a Piper Arrow (IO360). not approved for mogas and even more so adding LASAR.
LASAR improved performance as well as economy (nearly 20%). Plug life 900+ hours. When mogas was uses to experiment, consumption dropped an additional 1 gph, in addition to engine smoothness (hard to believe that one, but it was well documented).
There is no earthly reason for airplanes not to be using the stuff (100LL). The vapor lock issue is another old wives tales, as proven by EAA.
Lycoming, some 20 years ago, was absolutely addament that mulitgrade Shell 15/50 not be used, yet today, it tops their list of lubricants. Now they finally discovered mogas. At some point they may even discover FADECs, and their technology may forget the 30s.
In case anyone is interested, one of the popular motorcycles uses "87" octane , with compression ratio of 12.5:1, and is "not" FADEC equiped.
TT
RV-10 and will use mogas.

BTW, in the Piper Arrow experiment, EGTs and CHTs dropped using mogas and had to lean for best mixture. Same with Continental O470 sans LASAR, EGTs and CHTs dropped, and economy improved
 
So to expand on that, does anyone out here have any personal experience using MOGAS or 50/50 mix with 100LL on a high compression (10:1) IO-360?
 
They seem to be behind Superior.....

They seem to be behind Superior's certified Vantage engine (an O-360 clone) which has this in it's TCDS....

Motor Gasoline (R+M/2) (See Note 7) ASTM D4814, Min Octane 91 (no alcohol)

http://www.superiorengines.com/PDF/VantageEngine/E00001SC_TCDS.pdf

Both engines use the same carbs.... Note 7 talks about the need for airframe testing...

But, talking about octane....

Is the 93 octane Lycoming mentions measued on the "R" scale, "M" scale or the average (like our US auto gas)?

gil A
 
Not quite

tacchi88 said:
There is no earthly reason for airplanes not to be using the stuff (100LL). The vapor lock issue is another old wives tales, as proven by EAA.
Lycoming, some 20 years ago, was absolutely addament that mulitgrade Shell 15/50 not be used, yet today, it tops their list of lubricants. Now they finally discovered mogas. At some point they may even discover FADECs, and their technology may forget the 30s.
In case anyone is interested, one of the popular motorcycles uses "87" octane , with compression ratio of 12.5:1, and is "not" FADEC equiped.
TT
RV-10 and will use mogas.

BTW, in the Piper Arrow experiment, EGTs and CHTs dropped using mogas and had to lean for best mixture. Same with Continental O470 sans LASAR, EGTs and CHTs dropped, and economy improved
Click to expand...

But VL is not an old wives tale, Thats why Peterson cannot offer STC's to every IO360 equipped airplane.....See the previous post about in flight pump failure...I agree the engine will be perfectly happy with a resaonable CR and a well designed fuel system.

Trouble is we do not have well designed fuel systems because of the mechanical fuel pump, combined with our low wing fuel tanks.

You can get away with it with blast tubes on the mechanical pump etc, but be careful when taking of from hot and high airports on Mogas..

Also remember the only reason hot rod bikes get away with low quality fuel is due to knock sensors that adjust the timing to get the most out of the fuel without detonating...we don't have that technology sadly, but it seems 91 octane gas is OK with a standard Lyc running up to 36 degrees of max advance...Maybe even more.

One of us also runs 87 gas in an 360, not sure what the max timing is set to though.

Frank
 
frankh said:
Also remember the only reason hot rod bikes get away with low quality fuel is due to knock sensors that adjust the timing to get the most out of the fuel without detonating...we don't have that technology sadly, but it seems 91 octane gas is OK with a standard Lyc running up to 36 degrees of max advance...Maybe even more.
Click to expand...
Knock sensors have been tried on Lycomings. The problem is that the 4 cylinder air cooled engines are so noisy that the knock sensor can't recognize the knock.
 
Exactly

So my point on knock sensors is that we are limited on the technology so while it maybe tempting just to throw the cheapest gas in there because the crotch rockets can, we really need to be cautious as there are limitations and our engines are very expensive..:)
 
Wives tale

Frank,
In 29 years in aviation, I've heard the "old Wives tale" that mogas will cause vapor lock. At altitude. 14.800 feet is considered by many as vapor lock territory, yet there have been autos atop of Pikes Peak for decades.
Vapor lock happens when fuel boils as a result of lack of pressure. A weak pump in a hot area is indeed ripe for VL, but altitude did not a cause it, lack of pressure did. And most certainly, the archaic Lycoming would not.
One of EAA's test beds included their test 150 with a "special brew" that would have boiled on the ground in mere sunlight. The 150 struggled all the way up to as I recall to nearly 20K. No VL occured.
Some old manuals such as Piper Cubs, recommend using gasoline available at the gas pump, including illustrations of such. AV gas was an option. Mogas during the heyday of the Cub was nothing like it is today, in octane numbers unleaded included.
Bottom line, we can trash this topic to death, but aviation has to get it's own head straight. There is nothing wrong with mogas, and it's about time aviation begind enbracing electronics, which now have beeb around longer than Lycoming has attempteds to figure out how to prevent crank failure.
Maybe when lead will cease to exist, and no lead is present to contiminate oil, who knows?
My comments on the useage of mogas and it's benifits, includes Lycoming, Continentals, and Rotax over a period of 21 years.
The Conti I mentioned has been using 87 since the STC became available. It has most definetely improved it's reliability. A few years back, when the "dreaded" MTBE was in use, and some claimed that it will spoil if let standing, and ruin all sorts of components, said C182 accumulated a whole 4 hrs, and during it's first time out. That gasoline had nearly 12 month to sour.
I signed off the annual, and the owner was concerned (and a firm believer in mogas), it fired up on the 4 th spin of the prop, and exibited no ill effects whatsoever. This was some 12 years ago.
The fact that Lycoming is coming around to mogas is a step in the right direction. Now if we can only add electronics.
TT
RV10/Mogas
 
I don't do old wives tales!..

:)
tacchi88 said:
Frank,
In 29 years in aviation, I've heard the "old Wives tale" that mogas will cause vapor lock. At altitude. 14.800 feet is considered by many as vapor lock territory, yet there have been autos atop of Pikes Peak for decades.
Vapor lock happens when fuel boils as a result of lack of pressure. A weak pump in a hot area is indeed ripe for VL, but altitude did not a cause it, lack of pressure did. And most certainly, the archaic Lycoming would not.
One of EAA's test beds included their test 150 with a "special brew" that would have boiled on the ground in mere sunlight. The 150 struggled all the way up to as I recall to nearly 20K. No VL occured.
Some old manuals such as Piper Cubs, recommend using gasoline available at the gas pump, including illustrations of such. AV gas was an option. Mogas during the heyday of the Cub was nothing like it is today, in octane numbers unleaded included.
Bottom line, we can trash this topic to death, but aviation has to get it's own head straight. There is nothing wrong with mogas, and it's about time aviation begind enbracing electronics, which now have beeb around longer than Lycoming has attempteds to figure out how to prevent crank failure.
Maybe when lead will cease to exist, and no lead is present to contiminate oil, who knows?
My comments on the useage of mogas and it's benifits, includes Lycoming, Continentals, and Rotax over a period of 21 years.
The Conti I mentioned has been using 87 since the STC became available. It has most definetely improved it's reliability. A few years back, when the "dreaded" MTBE was in use, and some claimed that it will spoil if let standing, and ruin all sorts of components, said C182 accumulated a whole 4 hrs, and during it's first time out. That gasoline had nearly 12 month to sour.
I signed off the annual, and the owner was concerned (and a firm believer in mogas), it fired up on the 4 th spin of the prop, and exibited no ill effects whatsoever. This was some 12 years ago.
The fact that Lycoming is coming around to mogas is a step in the right direction. Now if we can only add electronics.
TT
RV10/Mogas
Click to expand...

I never did say there was anything wrong with mogas, nor did I say Altitude causes VL.

What I said was we normally have a mechanical fuel pump in a hot environment and this can (and has) lead to VL issues at high airports on hot days.

A mechanical fuel pump is a marginal system, made worse with a low wing airplane.

a "weak pump" is irrelavent....if the fuel pressure is allowed to get low at the inlet to the pump and the pump has to do any significant sucking the fuel will boil..Its simply that Mogas has a higher vapour pressure than 100LL and is therefore more prone to VL than 100LL.

This is why the C150 never Vl'd...It had positive head over the fuel due to vleocity pressure on the tank vents and the fact the wing tanks were above the carb and/or fuel pump.

The RV is not the same animal,...It has to do some sucking up hill..albeit hopefully very minor. with a hot pump to boot..If the suction reduces the pressure to below the vapour pressure of the fuel..It will boil, pure and simple...And of course the higher the temperature of the fuel the higher the vapour pressure.

A properly designed fuel system (like the one I built with the pumps in the wingroots) gets around this issue and makes it into a "hydraulically correct" system that cannot VL....In other words it emulates the C150 system albeit with more pressure.

Needless to ay my airplane never sees 100LL if I can help it either.

It would appear that providing there is adequate cooling to the mechanical pump we will get away with using Mogas, plenty of evidence to that fact...But you'll excuse me if my engine never has a mechanical pump bolted to it..

Frank
 
RVbySDI said:
Acronyms are only SIMPLE when said acronyms are defined!:confused:
Click to expand...

Ok you got me...

NPSHA = Net Positive Suction Head Available

NPSHR = Net Positive Suction Head Required

Volumes of info on what this means available via GOOGLE.

Being in the boiler business, we use these terms constantly are are very concerned with how the Vapor Pressure of a particular media will affect a pumps performance and its associated systems.
 
But what about ethanol?

It has become almost impossible to find mogas without ethanol in Michigan. Has anyone tried using 95% gas and 5% ethanol?
 
How much pump?

Excuse my ignorance here. I'm planning an IO-320 with a high pressure electric boost pump. Is that adequate for running mogas?

It is nice to see Lycomming embracing mogas.
 
Welll

dhusk said:
Excuse my ignorance here. I'm planning an IO-320 with a high pressure electric boost pump. Is that adequate for running mogas?

It is nice to see Lycomming embracing mogas.
Click to expand...

Yes it is...But its not the boost pump thats the issue....Make sure you have a good blast tube on the mechanical pump and it should be just fine...Not ideal from a hydraulic perspective but it should be OK.

Make usre your vent lines are open and there is no restriction upstream of the pumps...Give the system a good flushing before flight.

This is good practice anyway.

Frank
 
Thanks, Frank.

I plan on flushing my fuel system very well before first flight. I saw other comments about the blast tube and will definitely put one in.

Harold, you're right about mogas and ethanol in Michigan. I wonder if airports will start carrying mogas without alcohol in the future. Having to tote it to the airport seems a bit daunting, too.

Harold, I don't know if you remember me, but I visited you last year. I'm building a 9A. How'd your paint job turn out? I haven't had a chance to get over to see it.
 
With or Without Ethanol?

OK folks, my only question is if Lycoming is going to approve Mogas WITH ethanol, or require it to be WITHOUT. If the first is true, this is a huge breakthrough. If the latter, then they are just following an already large crowd - and one that is soon going to find it next to impossible to find auto gas without the grain-derived stuff.....

Paul
 
With or without

We already have 10% in most of Florida, and so far, no issues. We did 4 hrs. hop scotching last Saturday, the engine didn't seem to care. No noticeable change in consumption or performance.
TT
RV10
 
tacchi88 said:
We already have 10% in most of Florida, and so far, no issues. We did 4 hrs. hop scotching last Saturday, the engine didn't seem to care. No noticeable change in consumption or performance.
TT
RV10
Click to expand...

FOUR WHOLE HOURS!? Wow - a complete test program!:p:D Sorry, I know, sarcassm is really not my strong point....

My "problem" with ethanol comes from seeing fuel system components in various engine systems become soft and gummy, or disolve when ethanol is introduced as a component in the fuel. When someone can PROVE to me that the Lyclone is ethanol-proof, I will fly auto gas (I used to do it in my old J-3) - but the "damage" generally takes months to develop.

Paul
 
There's no breakthru here. I've been running ethanol-free 87 mogas for over 800 hours. There's been times where I've run fuel with ethanol in it, generally trouble free but prone to vapor lock on the ground, even with the pump on. Ethanol is going to be a given in the future so we need to start thinking of ways of dealing with it. Resistance is futile....The era of ethanol-free mogas will soon be over.

Cars nowadays deal with vapor lock very effectively by running pressurized fuel from the tank at 100+ psi. If you want to see first hand how effective this is (pun intended), let your car sit for 15 minutes to heat soak the fuel rail. With your fingernail open up fuel rail schrader valve where you would attach a pressure gauge, and you'll find our quickly how hot mogas can get. Pretty close to burning hot.

What we need is a system like the old PS-5C pressure carbs which have a vapor return line constantly purging cool fuel not just up to the carb or servo, but inside the unit. Although a purge valve is very helpful for starting which the AFP systems have, its still not the best solution because the hot fuel isn't constantly being purged.

The fuel either has to be under high pressure right up to the intake valve, or it has to be constantly purged to keep the fuel cool throughout the fuel delivery system.
 
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Ethanol

I know the AFP FI system is compatible with ethanol and my pump in the wingroot systems will take care of any VL issues...

Now there maybe a little stumbling on the ground because the injection lines will still get heat soaked, but this should clear with high fuel flow.

I am not particularly worried about ethanol, but I don't know for sure if it will soften the proseal...Haven''t needed to check this out yet as ETOH free gas is still avilable at an airport withing 10 minutes flying time from here.

I suspect i will be using etoh gas soon however..:(
 
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ECI has vapour return

Does anyone know the specifics about the newer ECI FI system? Specifically how much fuel is returned to the tank? Is it vapor only or a constant flow to keep things cool, or to maintain a certain pressure to the injectors etc?

Bevan
RV7A wiring
 
Folks, this is timely news. As you might have heard, EPA is taking a real interest in leaded avgas. Now, on top of that, EPA is proposing a drastic (over 10x) reduction in the allowable ambient (outside) air standard for lead. It is possible that areas around certain indstries and larger GA airports could violate this standard. If that happens, look out.

I am developing a paper for a refining conference discussing this very topic (it's part of my day job) and will post it once it's ready for prime time.

As I've said before, we can choose to phase out 100LL in an orderly fashion or we can be pushed, perhaps in a direction we don't want to go. We don't need any more bad press for aviation and "you're killing my baby with all that lead raining down from the sky" isn't going to spin well for us. Once EPA changes the ambient lead standard (a few months), expect lots of public scrutiny of GA.

As for EtOH, well, that's another problem all together. I don't know of any certified engines or STCs that allow EtOH with the exception of the Rotax 912 series. The use of EtOH in mogas is an entirely political issue, not a scientific one, and nobody can predict where that will go.

TODR, happy mogas user
 
Seems like a no win

situation...

FAA won't allow etoh in gas (for certified birds anyway), The states won't allow non ETOH gas to be available..and now 100LL might have to go away as per the DEQ.

And airplanes will be fueled with what exactly?

Frank
 
No secret

rodcritt said:
The Vanguards don't seam to have any trouble with Ethanol. What?s their secret? All RV's All Lyco's
http://www.ethanolairshows.com/
Click to expand...

I bet the engines are perfectly happy on ETOH...They simply changed out any incompatible seals and opened up the jets to increase the mixture ratio..The proseal in the tanks?..i don't know.

The big problem (if indeed it is a problem) is the extra water the ETOH will absorb..Seems to be some evidence that this can be mitigated with a hygrometer...I.e specific gravity increases with extra dissolved water...The theory being this water will fall out of solution at low temperature and yer engine stops.

Now of course they don't say what you would do with the 42 gallons of water contaminated fuel you just got in your cans (or wingtanks) but if it were dispensed at the airport it should be a controllable sutuation.


Oh and of course the range has just been cut by what a third? and ETOH is still more expensive than gasoline so if you don't mind an effective cost of $9 a gallon it should be no problem at all...:)

Frank
 
Steve said:
The story says mogas is OK with Lycoming, but the airframer has to approve it's use, too.
I've never seen 93 octane gas in northern Utah. Phillips has 92 and everyone else has 91 premium.

running 100LL for now,
Steve
Click to expand...

Higher altitude locations they cut back on the octane number in the gas sold.



http://en.wikipedia.org/wiki/Octane_rating

excerpts below:

"For each 1000 feet of altitude the atmospheric pressure will drop by a little less than 11 kPa/km (1 inHg). An engine that might require 93 octane at sea level may perform at maximum on a fuel rated at 91 octane if the elevation is over, say, 1000 feet."

"In the Rocky Mountain (high altitude) states, 85 octane is the minimum octane and 91 is the maximum octane available in fuel. The reason for this is that in higher-altitude areas, a typical combustion engine draws in less air per cycle due to the reduced density of the atmosphere. This directly translates to reduced absolute compression in the cylinder, therefore deterring knock. It is safe to fill up a car with a carburetor that normally takes 87 AKI fuel at sea level with 85 AKI fuel in the mountains, but at sea level the fuel may cause damage to the engine. A disadvantage to this strategy is that most turbocharged vehicles are unable to produce full power, even when using the "premium" 91 AKI fuel. In some east coast states, up to 94 AKI is available [5]. In parts of the Midwest (primarily Minnesota, Illinois and Missouri) ethanol based E-85 fuel with 105 AKI is available"
 
Paint Job is Fabulous

dhusk said:
...
Harold, I don't know if you remember me, but I visited you last year. I'm building a 9A. How'd your paint job turn out? I haven't had a chance to get over to see it.
Click to expand...
It's Howard, but everyone does it. The paint job, done at Sturgis Aviation at KIRS is great. I recommend them strongly. Check my website for a couple of pics.
 
4hrs

Ironflight said:
FOUR WHOLE HOURS!? Wow - a complete test program!:p:D Sorry, I know, sarcassm is really not my strong point....

My "problem" with ethanol comes from seeing fuel system components in various engine systems become soft and gummy, or disolve when ethanol is introduced as a component in the fuel. When someone can PROVE to me that the Lyclone is ethanol-proof, I will fly auto gas (I used to do it in my old J-3) - but the "damage" generally takes months to develop.

Paul
Click to expand...

Paul,
Indeed 4 hrs may not be much at all but the alky has been here for some time with the cut rate stations and the majors for about 5 months, depending on area.
We have yet to encounter any problems. We're not the only ones using the stuff, just about everyone on our field uses mogas. Even the T/Craft I occasionally fly, may sits for months, between flights, with no ill effects.
As to what alky can ruin, it will take E85 to damage what is already in our dinosaurs. The fix is simple, and gasket materials can be cut in the same "Dyes" (no pun intended) and rubber that resists it, is available and already in use.
Our biggest problem is aviation itself. We're still using 110 year old technology to ignite our mixture, what will it take to replace a few gaskets or rubber seals?
Fact of the matter is that mogas has been used for some time, and most everyone using it has experienced improvement, especially in the pocket book.
The aircraft we flew with 4 hrs, has been using mogas since it first flew 400hrs+ ago. Used AV gas "once" and the engine balked.
The other AC we fly is a C182, using it since the STC became available. Mogas lower consumption better perfoemance. AV gas higher consumption less performance for the last 700 hrs. The 182 does not have a fuel pump, and here in Fl., we experience many hot days. No problems.
In our opinion, mogas is the way to go, and ratner than the aviation complaining and making excuses, applaud Lycoming for doing something right for a change, and for helping taking a little bite out of our "habit."
TT
RV10-/Mogas
 
Mogas & Ethanol

Hard to get excited about this. Mogas without ethanol has not been available anywhere in Maryland for a couple of years. Even the EAA Mogas STC is not valid for Mogas with ethanol in it. We need someone to do some serious testing on making an O-360/320 work with Mogas & ethanol and then sell an STC for it.
 
Ethanol

If for no other reason, it makes economic sense to use mogas. Since it may be hard to get in the near future, can someone please tell me exactly what is the danger. What seals might be affected? And, why would not future parts be fitted with seals that will not be harmed? Thanks, just wondering.
 
robertb328 said:
If for no other reason, it makes economic sense to use mogas. Since it may be hard to get in the near future, can someone please tell me exactly what is the danger. What seals might be affected? And, why would not future parts be fitted with seals that will not be harmed? Thanks, just wondering.
Click to expand...

I ask that same question every time a thread like this comes up, (not becasue I like to be argumentative, but because I would REALLY like to be able to use the cheapest fuel around!) and all I get is the sound of crickets chirping......:(

The MOGAS users all say they haven't had a problem in a couple hundred hours, and "hey, that vapor lock thing is a myth!" But I am too much of an engineer to trust to anecdotal evidence - I would like to see a real study done.

I am suspecting that if 100LL goes away, someone will have to do one - simply becasue the certitified fleet HAS to have evidence to allow a change like that!

Paul
 
Here's a thought...

I'm guessing the airboat guys don't use 100LL so they must be running mogas.

Anyone talked to them about what they are finding? I'm thinking those lycoming powered airboats are going well beyond TBO on autofuel.
 
Evidence

Ironflight said:
I ask that same question every time a thread like this comes up, (not becasue I like to be argumentative, but because I would REALLY like to be able to use the cheapest fuel around!) and all I get is the sound of crickets chirping......:(

The MOGAS users all say they haven't had a problem in a couple hundred hours, and "hey, that vapor lock thing is a myth!" But I am too much of an engineer to trust to anecdotal evidence - I would like to see a real study done.

I am suspecting that if 100LL goes away, someone will have to do one - simply becasue the certitified fleet HAS to have evidence to allow a change like that!

Paul
Click to expand...

Not sure if this would be of any interest, but in the late 70s when lead was on it's way out, we need to run an engine on our dynomometer. The engine was a 750CC two stroker racing engine (actually a modified street version) It called for high octane gas. The local station was already out of the leaded fuel so we simply used the unleaded. Octane numbers were close enough, and it was not a "trashing" session, but simply to test a few mechanical changes made to the engine.
The results were surprising, not as a result of the changes (they were mechanical changes not for power). Said engine operated at a maximum of 9000 rpms with bursts of 11.000 It produced 105 at 9K and 115 at 11K.
The test session proved the mechnical mods were acceptable, and decided to push the envelope. We did several full power pulls, up to 15.000 rpms and delivering near 150 hp. We did so for several pulls, but finally stopped since the engine had been ready for tear down, and hand grenading a worn engine was not nice.
What was unexpected was that the crankshaft was showing signs of strain. We determined that 15K was not the place to be. The rod bearing were simply not up to those speed. Aside from that, the rest was normal.
At the next event, we decided to use unleaded high octane rather that leaded. Top speed increased considerably, since the engine was over reving and had to chage gearing to take advantage of the "new" power, hence the increase in top speed. nearly 18mph at 9K.
The engine cooling remained stable and we had to add a higher temperature thermostat, since our operating temp was lower than normal. What a deal. There after for the next year before retiring unleaded fuel was used.
There was no ethonal then, but the octane additive was MTBE, a methonal derivitive.
Years later, I did the unthinkable on my Arrow equiped with LASAR. The Arrow was a 180 hp version and had to use 100LL with LASAR. Tried 93 mogas (5 gal on the right tank). Switched tanks, and much the same as the dynoed race engine, the IO360 had to be leaned since EGT dropped significantly. Same performance but 1gph lower fuel flow. Swithched back and forth the engine ran smoother and with less fuel for the same power setting than AV gas each time it was switched. Unfortunately, it was a certified AC and I was not interested in running on mogas due to the legalities, although it was very tempting. No VL either.
FWIW
TT
RV10/mogas/LASAR
 
Lycoming so what?

Until they actually approve it (if they do) Lycoming's position has always been NO auto fuel (even under STC). Now they are saying they are working on approval under ASTM D4814 which is fuel without ethanol ..... is there something missing here?

We just might get an approval for something that does not exist!

Ken
 
Exactly

Ironflight said:
I ask that same question every time a thread like this comes up, (not becasue I like to be argumentative, but because I would REALLY like to be able to use the cheapest fuel around!) and all I get is the sound of crickets chirping......:(

The MOGAS users all say they haven't had a problem in a couple hundred hours, and "hey, that vapor lock thing is a myth!" But I am too much of an engineer to trust to anecdotal evidence - I would like to see a real study done.

I am suspecting that if 100LL goes away, someone will have to do one - simply becasue the certitified fleet HAS to have evidence to allow a change like that!

Paul
Click to expand...

Well VL is NOT a myth...it can and does happen, but with precautions it seems the standard fuel system gets away with it...For me, I'm too much of an engineer too and happen to design a high vapour pressure pumping system or two in my professional career.

The one thing you will never find in pumps trying to lift high vapour pressure liquids.

Seeing as there are a few vairables that affect the vapour pressure in aircraft (varying upstream pressure due to flowrate, high temps occasionally, altitude) and generally sucking on fuel with a hot pump is not helping I took the cautious route and re-designed the fuel system.

For me the unknowns of the standard system were a bigger fear than running a properly designed (but electrically dependant) fuel delivery system..I.e pumps in the wingroots.

But it sure is nice to be able to use the least expensive fuel..

I know the Airflow performance FI system is compatible with alcohol, the logevity of the proseal is theonly unasnwered question in my mind..Oh and will i get stumbling on the ground ue to vapourization in the FI lines.

As alcohol free mogas is available at a local airport for cheaper than I can buy regular in town right now its not a motivator to change.

I'm not sure how much flying I will be doing if prices start heading north of $6 a gallon though..

Frank
 
Ken said:
Now they are saying they are working on approval under ASTM D4814 which is fuel without ethanol ..... is there something missing here?
Click to expand...

I'm having same question. However they actually say "...conforming to either Euro Norm EN228 or ASTM D4814" and EN228 is actually with 5 vol.% with ethanol and what I read it's expected to be raised up to 10 vol.% some day... at least currently it may contain 5 vol.% of ethanol.

Whether they'll rule ethanol out is the interesting question.
 
There is a discussion on this same thing with a comment on the feasibility of certifying these engines with lower octane fuel. The reality it seems, is that lycoming will most likely have to drastically reduce the CHT redlines to prevent detonation during the certification process. The 93 Oct auto fuel is relatively equal to about 88 oct. avgas (different standards), so the anti-detonation margins are gonna be pretty slim on a Angle valve.
 
Words are words...

Pirkka said:
I'm having same question. However they actually say "...conforming to either Euro Norm EN228 or ASTM D4814" and EN228 is actually with 5 vol.% with ethanol and what I read it's expected to be raised up to 10 vol.% some day... at least currently it may contain 5 vol.% of ethanol.

Whether they'll rule ethanol out is the interesting question.
Click to expand...

If you read all of the actual Lycoming news release, they left themselves an "out"....:)

Unleaded 93 AKI automotive gasoline conforming to either Euro Norm EN228 or ASTM D4814 will be the basis of this Lycoming specified fuel. Supplemental requirements within the scope of the existing standards will be stated as necessary for safe operation in aviation applications.

They can restrict specifications "within" the EN228 and ASTM specifications (no ethanol?)...

gil A
 
mogas v 100LL

N941WR said:
I'm guessing the airboat guys don't use 100LL so they must be running mogas.

Anyone talked to them about what they are finding? I'm thinking those lycoming powered airboats are going well beyond TBO on autofuel.
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I just bought an airboat with a 270/250 hp Lycoming engine. I was debating the question of using 100 LL or the highest octane mogas. I researched the issue online and found this forum thread. I joined the site just to get involved in this disucssion. I didn't realize my curiousity was also the subject of a huge, national discussion. The seller used 100LL but after reading these posts I will try high-octane unleaded with ethanol.
My only concern here is water. I will be using the airboat primarily in winter months for ice-fishing in very low temps (as low as 0F) and am worried about being stranded in the middle of a great lake at night. This is a risk that resembles that of ditching an aircraft I guess. I will be using it before ice fishing and will update you on the performance with mogas.
 
Dart,

Welcome to the VAF forum. Now if we can get you to drop the ?boat? and add ?plane? after the air, all would be right with the world. ;)

Try to avoid ethanol as much as possible. There is a big debate as to what it will do to the engine in the long run, if anything.

The EAA sells this test kit for $15, which will help you check for ethanol. It can also be used to drain the water of your tanks, if they have a quick drain on the bottom.

They also have a number of articles on the subject that might be worth reading, here is one.

(PS. Having grown up in Mid-Michigan and spending a lot of time on the lakes, I understand your concern regarding getting stranded out in the open water.)
 
I like Frank's thinking

frankh said:
For me the unknowns of the standard system were a bigger fear than running a properly designed (but electrically dependant) fuel delivery system..I.e pumps in the wingroots.
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Frank, you eliminated a BIG element of a I0360 that had me concerned for Mogas use- the heat soaked mechanical high pressure pump. That pump is behind the engine and even with a well designed blast tube, It is heat sink: And the biggest vapor point of an injection system. And I would assume You have no gas-collator? And the injection spider does have a vapor purge valve?

:rolleyes: hmmm, So now if one wing pump was on the same backup electrical system as the backup EFIS and pMag/Emag/Smag.. thingy...hmmmm
how diabolically delicious this backup E-system could be.
Once I was firmly in the carbureted camp, But now, hmmmmm
 
az_gila said:
If you read all of the actual Lycoming news release, they left themselves an "out"....:)

Unleaded 93 AKI automotive gasoline conforming to either Euro Norm EN228 or ASTM D4814 will be the basis of this Lycoming specified fuel. Supplemental requirements within the scope of the existing standards will be stated as necessary for safe operation in aviation applications.

They can restrict specifications "within" the EN228 and ASTM specifications (no ethanol?)...

gil A
Click to expand...
I attended the presentation at OSH by Lycoming for this gas. It is unleaded auto gas (which is ASTM D-4814 whether it has ethanol or not). But this is the catch, as az_gila alluded to. The Lycoming rep said he would be attending the ASTM meeting that is being held in Tampa, FL next month to ask for a special ASTM D-4814 sub-spec for this fuel. It would be 93 AKI, tighter RVP and a few other tighter specs and of course no ethanol. I d**n near died laughing. This fuel is going to be more boutique than 100 LL. I asked him where were we going to get a special mogas for our airplanes since no service station would have it and we haven't been able to convince airports to provide mogas. This isn't going to happen in our lifetime.

That said, there is a much better prospect on the horizon. The DOD is going to be attending the same ASTM meeting asking for a spec for 91 octane unleaded avgas, which will essentially be 100 LL w/o lead. They need it for their drones. My guess is that they will get this fairly quickly, as in months or a year, then the refineries have to ramp up. I hope Lycoming will jump on this bandwagon and abandon their own spec, because 100 LL w/o TEL is 93 MON. Since it as an avgas spec airport fuel distributors will be willing to deliver it to airports. However we are still in the same boat, we have no tanks and pumps on most airports for another gas service. But this might work if FBOs see the advantage to having a fuel available for 70% of GA in place when 100 LL goes away ... soon. And they will be able to fuel up any drone that lands on their airport.:D Since it will probably take 1 to 2 years to get this spec into production, now is the time to start working on getting mogas service on your airports. Now that ethanol is being put into all of the gas at local service stations, you can reason with the FBOs that they no longer have to compete with the local service station to deliver mogas for your airplane. The federal RFS mandate is cutting out their competition. If they get the infrastructure in now, they can put mogas in it, and the new unleaded avgas when it comes out. They are going to still need their 100 LL tank for the SwiftFuels replacement for 100 LL.;)
 
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N1593Y said:
The DOD is going to be attending the same ASTM meeting asking for a spec for 91 octane unleaded avgas, which will essentially be 100 LL w/o lead. They need it for their drones.

...

And they will be able to fuel up any drone that lands on their airport.:D
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I realize this is an old thread, but just came across it. I work at a "Drone" Air Force Base... although we prefer the term "RPA" (Remotely Piloted Aircraft). We're still using 100LL in our aircraft and no plans I'm aware of to change to anything else. Also, it's worth mentioning these aircraft can't land just anywhere for a number of reasons, not the least of which is FAA restrictions on where we can operate. So, don't expect an entrepreneur hoping to sell fuel to the DOD to make this fuel availabile at your local FBO.
 
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