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Can the IO540 run mogas?

Yes, if it's 8.5:1 compression....same cylinders and pistons as a O-360.

We used to taxi our Pawnees up to a gas station in the '70's, working off roads and buy mogas. They had the 230 horse, derated
O-540's.

Best,
 
One other thing...

In order to do this, wouldn't you have to protect your fuel tank interiors somehow? I thought the mogas causes corrosion in the tank and lines, no?
 
In order to do this, wouldn't you have to protect your fuel tank interiors somehow? I thought the mogas causes corrosion in the tank and lines, no?

If the FAA approves MOGAS for aviation, it will not be the same stuff you get from the pump at your local gas station. It will more than likely be ethanol free and won?t have the other additives you get in your pump gas. Thus you will have no problems with corrosion. If corrosion is a real fear or not, I don?t know.
 
Is the question WILL a 8.5:1 IO540 run on Mogas or is it APPROVED to run Mogas?

As I understand it, the IO540 is not approved even though it has the same compression as many 360s that ARE approved. See Lycoming SI1070. In Europe we now have unleaded Avgas (UL91 or 91/96UL) which is approved for many 540 models.

The issues with Mogas are well documented but in summary:

- it is cut with higher vapor pressure for auto use which can lead to vapor lock. The VP is not consistent and changes with the seasons.
- it us getting near impossible to obtain Mogas without significant percentages of ethanol. As you mention, ethanol can attack various components unless you make some mods. Also, there is an issue where any water in the tank tends to bond with the ethanol in preference to the gas and drop it out of solution. You therefore lose your anti-knock agent (short version!)
- The stuff you get at the gas pumps is not subject to the same quality controls as Avgas.

Having said that, I believe your experimental rules allow you to use it and I know there will be endless posts saying how wonderful it is...... And, yes, there are various ways to mitigate many of the issues. What you need is a US equivalent of our UL91 - but it's an environmental bonus and only a very small financial one.
 
Did a 2.4 hour Phase 1 testing flight last week in my IO-540 V4A5 RV-10. Left tank 100 LL, right tank pure 90 octane ethanol free "Recreation Fuel" a local gas station started selling recently. Took off and landed on the 100 LL and put 1.8 hours on the right tank at altitude's up to 9500' msl. The engine ran great and virtually no noticeable differences showing on the engine page. The Lycoming tech guys at the Lycoming presented engine dis-assembly/re-assembly seminar at Airventure I attended a few years ago stated the engine would be very happy running mogas. Next time up I'll do some more testing but liking that the rec fuel is more than a $2 per gallon savings.
 
Did a 2.4 hour Phase 1 testing flight last week in my IO-540 V4A5 RV-10. Left tank 100 LL, right tank pure 90 octane ethanol free "Recreation Fuel" a local gas station started selling recently. Took off and landed on the 100 LL and put 1.8 hours on the right tank at altitude's up to 9500' msl. The engine ran great and virtually no noticeable differences showing on the engine page. The Lycoming tech guys at the Lycoming presented engine dis-assembly/re-assembly seminar at Airventure I attended a few years ago stated the engine would be very happy running mogas. Next time up I'll do some more testing but liking that the rec fuel is more than a $2 per gallon savings.

According to the article, it appears as pipistrel is looking for lycoming to certify the gas for use so that would be a leap.
 
Good on em...

I happen to run into this article today which leads me to believe pipistrel is attempting to gain lycoming certification to run certain engines on mogas.

Tom,
I ran Non-Ethanol 91 Octane in my Harmon Rocket's 10.4:1 IO-540 C4B5 for 5 years. I currently run it in my 8.5:1 RVX. It's available all over FL and other parts of the USA. http://pure-gas.org/ Works great and is $.4.20 a gallon here. Ethanol's big issue is retaining water within the fuel, hence using Non-Ethanol.
In 25 years of MoGas RV flying, I have found it to run as well or better than 100LL with less plug fouling on the Mag side. My Electronic Ignition plugs never foul, regardless of fuel. There are lots of tips and pointers out there, I just use three.

1. Longer summer run-up (vapor lock prevention in summer)
2. Additives, Marvel Mystery oil, CD3. Optional, but work well.
3. Don't let it sit in the tanks for long periods.

It's the way of the future IMHO...
V/R
Smokey
 
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According to Lycoming Service Instruction 1070AB, the IO-540-D (RV-10) can use Automotive fuel (93 AKI) that meets ASTM D4814 standard. So what exactly is ASTM D4814, that I don't know?
 
Several people have raised the point here in this thread that water will bond to the ethanol in the fuel and fall out to the bottom of the tank, potentially causing problems.

Let me ask you this question - when was the last time you had to drain the fuel tank sump on your car to get rid of that water/ethanol mix at the bottom of the tank? Hmmm?
 
Vented VS Not Vented

Let me ask you this question - when was the last time you had to drain the fuel tank sump on your car to get rid of that water/ethanol mix at the bottom of the tank? Hmmm?

I think the reason we don't get water binding with ethanol in automobiles is the fact that the fuel system is Not vented to atmosphere, and actually under a slight positive pressure. The fuel system in my RV IS vented to atmosphere. So is my boat, lawn mower...
In Louisiana, ethanol-free fuel is widely available. It's the fuel of choice for boats around here for obvious reasons.
 
The venting

Onewinglo hit the nail on the head about the venting not being directly to the static atmosphere. There for less then a full tank on a cool damp dewey morning won't condensate moisture into the auto fuel tank as it will any tank that is directly vented. It's also the reason your car will harass you with the gas cap message or the check engine light when it consistently fails it's self vacuum test.
 
Gasoline boils when the fuel gets warm. When it boils expect vapor lock.

Auto Gas does not have the standards that 100 LL has. A FI engine has more fuel lines than a carb engine. The issue of whether auto gas will be suitable or not probably depends a great deal on the installation of the engine than the engine itself.

Keep the fuel lines cool and fuel below the boiling point...which we really don't even know. Also, if we run Auto gas in one tank only and use it only in cruise flight then it may be kept cooler by the nature of the fuel moving through it. Contrast that with the idea of taking off after a long taxi at low fuel flow....fuel is not moving fast through the lines and has time to heat up....and boil....and you find out during takeoff.
 
The true vapor pressure (TVP) of auto gas at various temperatures can be determined, RVP (Reid vapor pressure) is the vapor pressure at 100F.

RVP of auto gas varies between 7 and 15 psi depending on the area from summer to winter, respectively. 9 being the highest allowed by the EPA in summer.

So if you have a winter blend of fuel (RVP 15), at 5000ft elevation standard pressure is 12.2psi, and auto gas will boil at approximately 83F. Summer fuel (RVP 9) will boil at approximately 115F at the same altitude and pressure.

Summer auto gas will start to boil at about 126F at sea level, or 103F at 10,000ft.

If you run auto gas you'll want to know what kind of fuel you're using, especially if you're close to the edges of the temperature envelope.

I have a temp sensor at my pump inlet to measure fuel since I'm doing a short loop recirculation so I can keep an eye on it.
 

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AutoGas & Vapor lock

The point about "Let it sit" isn't totally accurate. Phase separation only occurs when the amount of water (from condensation) exceeds the ethanol’s ability to absorb the water. If auto gas sits too long in an aircraft tank (which may be many, many months) Carefully sumping the tank prior to flight "should" identify this issue (as what fuel is left may be a lower octane), requiring the fuel to be replaced..

So, if you keep the fuel under pressure, from the source, to the engine, vapor lock is impossible. At least that is what happens in auto's as the fuel pump is IN THE TANK. Wouldn't this (and other fuel system changes) work in airplanes? Yes, other fuel system changes include Teflon hoses (or other ethanol compliant materials), no 90* fitting to the engine, and heat shielded lines must be involved.

There are MANY in the experimental domain doing just that. I've been running 93 OCT E10 gas for years with absolutely NO issues. I have an independent fuel pressure system that turns ON my AUX pump (located in the cockpit) whenever that pressure goes below a set point plus 10 seconds of run time. As long as the fuel is under pressure, and "PUSHED" to the engine pump, vapor lock is impossible.

As far as phase separation is concerned, I've never seen it happen in my aircraft, even in the high humidity Florida environment. And the aircraft may sit for MONTHS at a time with no use.

A nice experiment might be to half fill a five gallon container with E10 gas, then start adding water until phase separation occurs. You will be surprised how much "condensation" it takes to force phase separation.... Unless you aircraft is parked outside and has leaky gas caps, you probably will never see it happen.

The IO-360 with the 8.5:1 compression requires a minimum of 91 octane. 93 octane E10 gas works just like 100LL....


Gasoline boils when the fuel gets warm. When it boils expect vapor lock.

Auto Gas does not have the standards that 100 LL has. A FI engine has more fuel lines than a carb engine. The issue of whether auto gas will be suitable or not probably depends a great deal on the installation of the engine than the engine itself.

Keep the fuel lines cool and fuel below the boiling point...which we really don't even know. Also, if we run Auto gas in one tank only and use it only in cruise flight then it may be kept cooler by the nature of the fuel moving through it. Contrast that with the idea of taking off after a long taxi at low fuel flow....fuel is not moving fast through the lines and has time to heat up....and boil....and you find out during takeoff.
 
So what happens to those temp numbers if the fuel pressure to the engine, from the tank, is 30PSI???? What is the boiling temp then??? Youe equations don't seem to include pressurized fuel flow.... Simple physics dictates that the boiling point would be MUCH higher. (Don't believe me, just see how food is cooked in a pressure cooker!)

The true vapor pressure (TVP) of auto gas at various temperatures can be determined, RVP (Reid vapor pressure) is the vapor pressure at 100F.

RVP of auto gas varies between 9 and 15 psi depending on the area from summer to winter, respectively.

So if you have a winter blend of fuel (RVP 15), at 5000ft elevation standard pressure is 12.2psi, and auto gas will boil at approximately 83F. Summer fuel (RVP 9) will boil at approximately 115F at the same altitude and pressure.

Summer auto gas will start to boil at about 126F at sea level, or 103F at 10,000ft.

If you run auto gas you'll want to know what kind of fuel you're using, especially if you're close to the edges of the temperature envelope.

I have a temp sensor at my pump inlet to measure fuel since I'm doing a short loop recirculation so I can keep an eye on it.
 
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As originally designed in the certified world, this could be true. Using what has been learned in the Auto fuel system world, NOT SO TRUE. Even with our open to atmospheric pressure fuel tanks, there are other methods available to alleviate these issues.

Exactly --

"Let it sit, and it will quit..."
 
So what happens to those temp numbers if the fuel pressure to the engine, from the tank, is 30PSI???? What is the boiling temp then???

Winter gas (RVP 15) will boil at 143F at 30psi, but that's 30psi absolute so if your reporting 30psig for your fuel pressure then we need to add 14.7psi on that, in which case it will boil at 173.5F at 44.7psia (atmo + fuel pressure). RVP 9 fuel is 214F at those pressures.

Yeah I'm not worried about pressurized fuel vapor lock, maybe for a hot start situation where the fuel has been heat soaked, but definitely not after the engine is running, with my system running 40psi.
 
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So what is the possibility of getting the fuel temps up to 173.5F, in the tanks, even sitting in Death valley????? And for that matter, even a temp of 143F?? Granted, the temp margin is less than 100LL, but certainly within reason for most of our flying conditions.

Winter gas (RVP 15) will boil at 143F at 30psi, but that's 30psi absolute so if your reporting 30psig for your fuel pressure then we need to add 14.7psi on that, in which case it will boil at 173.5F at 44.7psia (atmo + fuel pressure). RVP 9 fuel is 214F at those pressures.
 
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Water in the tank

If you have 1 m3 of air @ MSL and +77 F it can hold not more than 23 g
of water. That is 100% humidity.
To get 1 g of water in to a tank via ventilation you need at least 43 L (11 usg)
of air in to the tank. As for ethanol the aviation fuel standard allows up to 1 %.
I have used car gas 5% ethanol for more than 10 years in my superior IO-360.
No problems so far. The engine is clean inside.:)
 
So, from your numbers, keeping the tank full of gas is better than filled with air as, filled with gas, water from 100% humidity won't be absorbed....

If you have 1 m3 of air @ MSL and +77 F it can hold not more than 23 g
of water. That is 100% humidity.
To get 1 g of water in to a tank via ventilation you need at least 43 L (11 usg)
of air in to the tank. As for ethanol the aviation fuel standard allows up to 1 %.
I have used car gas 5% ethanol for more than 10 years in my superior IO-360.
No problems so far. The engine is clean inside.:)
 
So what is the possibility of getting the fuel temps up to 173.5F, in the tanks, even sitting in Death valley????? And for that matter, even a temp of 143F?? Granted, the temp margin is less than 100LL, but certainly within reason for most of our flying conditions.

I'd say it's not possible outside parking in a greenhouse. Care should still be used to avoid heat-soaking pressurized lines around the engine, as a best practice. Lower pressure FI systems are more of a risk obviously.
 
Definitely an accurate statement! A low pressure CARB (5-6 psi) system would require a pressure regulator near the Carb if the rest of the fuel system was at 30 PSI, as the Carb wouldn't tolerate the 30PSI. Still doable with the right hardware. Definitely non-certified..... But that's why we are "Experimental".....

My point to all these posts is that it's important to learn from past experiences, but not confined by their results. In the past, auto design methods were used in the aviation world, but FAA didn't allow changes once the certification process was granted. We have the ability to overcome those restrictions in the experimental domain! We can utilize modern day auto concepts to better our experimental aircraft! And just as new electronic concepts have migrated from the experimental domain into the certified world, so should other improvements...

I'd say it's not possible outside parking in a greenhouse. Care should still be used to avoid heat-soaking pressurized lines around the engine, as a best practice. Lower pressure FI systems are more of a risk obviously.
 
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So, given your calculations, what would be the fuel boiling point if the fuel from the tank was always ate 5-6 PSI? Putting a faucet pump in each wing root, backed up with the normal faucet pump in the fuselage of a carb'ed engine plane, would result in a constant 5-6 PSI pressure to the engine (in addition to the engine pump) all the time. Given that "other" design factors were implemented (no 90* fittings, heat protected lines, etc), what would be the MAX fuel temp that would be allowed?


The true vapor pressure (TVP) of auto gas at various temperatures can be determined, RVP (Reid vapor pressure) is the vapor pressure at 100F.

RVP of auto gas varies between 7 and 15 psi depending on the area from summer to winter, respectively. 9 being the highest allowed by the EPA in summer.

So if you have a winter blend of fuel (RVP 15), at 5000ft elevation standard pressure is 12.2psi, and auto gas will boil at approximately 83F. Summer fuel (RVP 9) will boil at approximately 115F at the same altitude and pressure.

Summer auto gas will start to boil at about 126F at sea level, or 103F at 10,000ft.

If you run auto gas you'll want to know what kind of fuel you're using, especially if you're close to the edges of the temperature envelope.

I have a temp sensor at my pump inlet to measure fuel since I'm doing a short loop recirculation so I can keep an eye on it.
 
So, given your calculations, what would be the fuel boiling point if the fuel from the tank was always ate 5-6 PSI? Putting a faucet pump in each wing root, backed up with the normal faucet pump in the fuselage of a carb'ed engine plane, would result in a constant 5-6 PSI pressure to the engine (in addition to the engine pump) all the time. Given that "other" design factors were implemented (no 90* fittings, heat protected lines, etc), what would be the MAX fuel temp that would be allowed?


Those equations come from the EPA Air Emissions Factors and Quantification AP 42, Chapter 7: Liquid Storage Tanks, so they're not just mine. The equation itself is derived from the nomograph. You can use the chart to plot any scenario you'd like.
 
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It's a gas gas gas...

My Dad ran 87 Octane Non Ethanol MoGas in our Families 0-470 powered 57' C182 for 20 years. He had the STC which was nothing more than a placard and a set of guidelines but appreciated. Thanks, EAA.
Dad had many precautions he followed in the FL humidity and heat that I later carried over to my own MoGas usage in my RV's and IO-540 equipped HR2. Dad always did long Run Ups on hot days and always used the boost pump below 2000'. He never spent alot of time on the ground on hot days and always mixed in Marvel Mystery Oil per the MFG recommendations.
I used and still occasionally use Non Ethanol Mogas in my Carb equipped RV4 and RV6X mixed with Marvel Mystery oil and 100LL. In my injected HR2 I ran a 75/25 mix (NE Mogas/100LL) and followed the Canadian Govt study guidelines I'll post below. When 100LL was over $6 bucks a gallon and you burn 22GPH on takeoff, every little bit helps.
Ive never had a problem with vapor lock and follow the steps above still to this day. I visit CO every Fall and use 100LL in the high country, exclusively.

MoGas isn't for everyone but if you fly alot and 100LL isn't convenient or affordable, it's an option.
:)
V/R
Smokey

https://tc.canada.ca/en/aviation/re...ars/airworthiness-manual-advisory-ama-no-5499
Canadian MoGas Advisory
 
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I happen to run into this article today which leads me to believe pipistrel is attempting to gain lycoming certification to run certain engines on mogas.

http://www.flyingmag.com/aircraft/p...2&spJobID=261589158&spReportId=MjYxNTg5MTU4S0

Can the engine run mogas? Here's Lycoming's list of approved fuels for their engine models. It assumes that the fuels are airworthy, and they specify that they don't believe that pump gas is airworthy.

https://www.lycoming.com/sites/default/files/SI1070AB Specified Fuels.pdf
 
Can the engine run mogas? Here's Lycoming's list of approved fuels for their engine models. It assumes that the fuels are airworthy, and they specify that they don't believe that pump gas is airworthy.

https://www.lycoming.com/sites/default/files/SI1070AB Specified Fuels.pdf

Not sure how you are interpreting this, but by my read Lyc clearly approves 93 octane auto fuel in the 540 C/D models, and most other 320/360 PV variants, as long as the vapor rating is A-4 (7-9.3 PSI) and oxygenates are less than 1%. Basically the summer blend fuel in most states (not sure about CA though, as I think they require greater quantities of oxygenates).

Their direct quote:

Fuels approved for use in Lycoming engines in Table 3 include the following types:
• Aviation Fuels (Table 1)
• Automotive Fuels (Table 2)

WHere does it say that pump gas is not airworthy, though I suppose by pump gas you mean something other than automotive fuel.

Larry
 
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Not sure how you are interpreting this, but by my read Lyc clearly approves 93 octane auto fuel in the 540 C/D models, and most other 320/360 PV variants, as long as the vapor rating is A-4 (7-9.3 PSI) and oxygenates are less than 1%. Basically the summer blend fuel in most states (not sure about CA though, as I think they require greater quantities of oxygenates).

Their direct quote:

Fuels approved for use in Lycoming engines in Table 3 include the following types:
• Aviation Fuels (Table 1)
• Automotive Fuels (Table 2)

WHere does it say that pump gas is not airworthy, though I suppose by pump gas you mean something other than automotive fuel.

Larry

Airworthy implies the entire system - airframe plus engine. The engine by itself will eat autogas just fine - the tricky part is the rest of the fuel system, both for ethanol tolerance and vapor lock. Lycoming cannot declare anything to be "airworthy" because that includes the airframe, which they have no control over. They can say what fuels are approved for their engine.

Airworthy means the entire system is good for it, as decided by the FAA - either through the original TC or an STC.
 
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Not sure how you are interpreting this, but by my read Lyc clearly approves 93 octane auto fuel in the 540 C/D models, and most other 320/360 PV variants, as long as the vapor rating is A-4 (7-9.3 PSI) and oxygenates are less than 1%. Basically the summer blend fuel in most states (not sure about CA though, as I think they require greater quantities of oxygenates).

Their direct quote:

Fuels approved for use in Lycoming engines in Table 3 include the following types:
• Aviation Fuels (Table 1)
• Automotive Fuels (Table 2)

WHere does it say that pump gas is not airworthy, though I suppose by pump gas you mean something other than automotive fuel.

Larry

https://www.lycoming.com/content/unleaded-fuels-part-1

Broadly speaking, both of these are fuels conform to ASTM Specification D4814 or Euronorm Specification EN228. These fuels are designed for ground vehicles and controlled to ensure proper startability, driveability, seasonal emissions control and of course, performance. As ground transport fuels, they are highly influenced by environmental regulations (EPA). They are not subject to aviation regulations (FAA). The specifications change on an almost yearly basis in response to changing environmental regulations and political mandates such as ethanol inclusion. What is made available to the market for retail consumption is "pump gas" which is NOT "fit-for-purpose" for aviation precisely because it is controlled for ground transportation purposes. So how did Lycoming, self-admittedly one of the most conservative engine companies in the world, approve "mogas" and what exactly did we approve?
 
Airworthy implies the entire system - airframe plus engine. The engine by itself will eat autogas just fine - the tricky part is the rest of the fuel system, both for ethanol tolerance and vapor lock. Lycoming cannot declare anything to be "airworthy" because that includes the airframe, which they have no control over. They can say what fuels are approved for their engine.

Airworthy means the entire system is good for it, as decided by the FAA - either through the original TC or an STC.

Right. True for certificated airplanes, not for Experimental airplanes. It's why, for example, you might see Jonas Marcinko land his Rotax-powered Kitfox on a back road and taxi up to a gas station for fuel. Lycoming appears to make the distinction because, as a conservative aircraft engine maker, they don't want Lycoming-powered airplanes crashing due to the way that that plane's ASTM D4814 mogas was formulated, stored, and pumped.

So how did Lycoming, self-admittedly one of the most conservative engine companies in the world, approve "mogas" and what exactly did we approve?

Lycoming approved "mogas" by controlling automotive gasoline properties differently than what is done for ground transport vehicle "pump gas." The specifics:

  • 93 AKI for detonation margin (hot day OAT and 500F cylinder heads).
  • Vapor pressure Class A-4 to prevent vapor lock.
  • No ethanol and maximum 1% oxygenates.
  • ASTM D4814 Revision 09b and EN228 Revision 2008:E.

That's pretty specific stuff and only one of those values is listed on the filling station pump.
 
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