MoGas in Aztec with IO-540

C

Cmercado

Pre-takeoff checklist
Joined
Jan 16, 2012
Messages
150
Location
San Juan, Puerto Rico
Display Name
Display name:
Charlie M
Guys,

I have a friend who was doing some misionary work in Haiti and he told me that they were flying Piper Aztecs IO-540 engines with mogas. He asked the pilots about it and they told him that they have no availability of avgas and that the plane worked perfectly with 91 octane...

Have you heard about this before? I thought that you can not use mogas in high compresion engines?

Do they know something we dont?
 
Cmercado said:
Guys,

I have a friend who was doing some misionary work in Haiti and he told me that they were flying Piper Aztecs IO-540 engines with mogas. He asked the pilots about it and they told him that they have no availability of avgas and that the plane worked perfectly with 91 octane...

Have you heard about this before? I thought that you can not use mogas in high compresion engines?

Do they know something we dont?
Click to expand...
You can use MOGAS in a lot of engines. There is even an STC out there for putting MOGAS in a DC-3
 
Cmercado said:
But as far as I know there is no STC for Mogas in IO 540. What about vapor lock?
Click to expand...

He's in Haiti, right? I bet the FAA or Haitian equivalent isn't looking too closely at the fuel he's using, until something happens. :rolleyes:
 
Cmercado said:
I know they dont give a dam about it... My concern is about safety... not regulations...
Click to expand...

I would not go flying in Haiti if you are concerned about safety. :no:
However, it might be safer in an Aztec burning Mogas than trying to cross country on the ground, with security and all.
 
Cmercado said:
Guys,

I have a friend who was doing some misionary work in Haiti and he told me that they were flying Piper Aztecs IO-540 engines with mogas. He asked the pilots about it and they told him that they have no availability of avgas and that the plane worked perfectly with 91 octane...

Have you heard about this before? I thought that you can not use mogas in high compression engines?

Do they know something we dont?
Click to expand...

I have 550 hours of burning 91 octane mogas in my IO-540. No problems, and I have saved roughly $12,000. Having to burn 100ll to avoid vapor lock is a myth.

The compression is 8.5-1.
 
Geico266 said:
I have 550 hours of burning 91 octane mogas in my IO-540. No problems, and I have saved roughly $12,000. Having to burn 100ll to avoid vapor lock is a myth.

The compression is 8.5-1.
Click to expand...

You are running poisonal-free 91 octane though aren't you?
 
Cmercado said:
But as far as I know there is no STC for Mogas in IO 540. What about vapor lock?
Click to expand...

Experimentals don't need no steenkin STC. :lol:

I run blast tubes to the mechanical pump and run the boost pump on take to altitude. No worries.
 
Last edited:
Geico266 said:
I have 550 hours of burning 91 octane mogas in my IO-540. No problems, and I have saved roughly $12,000. Having to burn 100ll to avoid vapor lock is a myth.

The compression is 8.5-1.
Click to expand...

Geico,
Are you using mogas exclusively? Do you mix with avgas everyonce in a while?
 
Geico266 said:
Have you seen what your $600 STC buys? :rofl:
Click to expand...

Yeah. It bought me all the flight testing that went into making sure the fuel system on the airframe and the fuel system on the engine was compatible with mogas.
 
Dead Stick said:
After all the flight testing that went into making sure the fuel system on the airframe and the fuel system on the engine was compatible with mogas.:rolleyes:
Click to expand...

I agree. But I truly believe that aircraft manufacturers are the ones that should be providing that info free of charge to their customers.... Goodwill and cheaper operating costs sell more airplanes....:yes:
 
I would have thrown rubbing alcohol in the PC12 to get out of Haiti! :)

Actually, I enjoyed the experience, but it sure was a reassuring sound hearing that PT6 spool up when it was time to go
 
Dave Theisen said:
I would have thrown rubbing alcohol in the PC12 to get out of Haiti! :)

Actually, I enjoyed the experience, but it sure was a reassuring sound hearing that PT6 spool up when it was time to go
Click to expand...


How many goats did you deliver?
 
Cmercado said:
I agree. But I truly believe that aircraft manufacturers are the ones that should be providing that info free of charge to their customers.... Goodwill and cheaper operating costs sell more airplanes....:yes:
Click to expand...

Actually, there has been some initiative towards that. Check out Lycoming Service Letter 1070Q.

http://www.lycoming.textron.com/support/publications/service-instructions/pdfs/SI1070Q.pdf

Scroll to page 5.

93 AKI approved for use in certain 360s, free of charge from Lycoming.

The catch is, the fuel needs to also be approved by the airframer. This is where you get into more issues. So in other words, the IO-360 in your Skyhawk might be approved for use on automotive fuel, but your Skyhawk might not be.

The STC route ends up being easier in many cases because it allows an engine/airframe combination to use a particular fuel. Basically gets past the political bickering that happens between companies.
 
FWIW, I would be extremely surprised if they had any issues running Aztec engines on 91 fuel. Were it my Aztec and that was what was available, I would do it without question. There were times I considered doing it with my Aztec anyway, but the logistics didn't make sense, and in the event of a crash/engine failure I didn't want anyone coming after me with pitchforks.
 
Ted DuPuis said:
FWIW, I would be extremely surprised if they had any issues running Aztec engines on 91 fuel. Were it my Aztec and that was what was available, I would do it without question. There were times I considered doing it with my Aztec anyway, but the logistics didn't make sense, and in the event of a crash/engine failure I didn't want anyone coming after me with pitchforks.
Click to expand...

Well... In the Caribbean avgas prices are reaching almost $8 a gallon:mad2::mad2::mad2:.......
Ethanol free 91 octane mogas is about $ 3.95.... I bet there are a lot more "unapproved" mogasers around here than up north....
 
I have been thinking that a little pressure in the fuel tank would make this vaporlock issue less of a problem. Like drop a cube of dry ice into a tank of mogas. A little dynamic pressure from a vent facing into line of flight. Like on a Cessna or a day tank with pressure source.
 
Yeah, that MIGHT work in a sealed tank. But you do realize that those tanks are vented for a reason.
 
Yes, I know they are vented for a reason.

"Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure, or nothing."
 
Last edited:
Cmercado said:
Well... In the Caribbean avgas prices are reaching almost $8 a gallon:mad2::mad2::mad2:.......
Ethanol free 91 octane mogas is about $ 3.95.... I bet there are a lot more "unapproved" mogasers around here than up north....
Click to expand...

Autogas is cheap in PR. In Eleuthera there was about a $1 per gallon difference. Not enough to worry about.
 
Cmercado said:
Well... In the Caribbean avgas prices are reaching almost $8 a gallon:mad2::mad2::mad2:.......
Ethanol free 91 octane mogas is about $ 3.95.... I bet there are a lot more "unapproved" mogasers around here than up north....
Click to expand...

The disparity in price is just as bad here. Although I've seen AvGas drop below $6 in most places (and even paid $4.50 in Florida), it's still easy enough to find $7-8, with 91 costing under $4.

But, I suspect people are less paranoid about enforcement there. The atmosphere seems to be more of a "Ya mon!" mentality.
 
NoHeat said:
Is that because the chance of vapor lock depends on the layout of the fuel lines and fuel pumps?
Click to expand...

That's part of it. Also concerns of compatibility with chemicals in the fuels. So for example even if LyContisaur approved ethanol fuels in the BeePipSna MaliDuk72, the airframer might have concerns about bladder materials, sealants, etc.

Basically, the FAA is smart enough to realize that a fuel system has components on both airframe and engine side, and one approving it doesn't necessarily mean the other will for system purposes.
 
Ted DuPuis said:
The disparity in price is just as bad here. Although I've seen AvGas drop below $6 in most places (and even paid $4.50 in Florida), it's still easy enough to find $7-8, with 91 costing under $4.

But, I suspect people are less paranoid about enforcement there. The atmosphere seems to be more of a "Ya mon!" mentality.
Click to expand...

Well..... There is the "Island Time" factor involved........ But the issue is that in Puerto Rico and the USVI we are regulated by the FAA.. The islands are a US territory... In other islands probably is another story..
 
Ted DuPuis said:
The disparity in price is just as bad here. Although I've seen AvGas drop below $6 in most places (and even paid $4.50 in Florida), it's still easy enough to find $7-8, with 91 costing under $4.

But, I suspect people are less paranoid about enforcement there. The atmosphere seems to be more of a "Ya mon!" mentality.
Click to expand...

Let's say you could run a really long hose from Racetrack and fuel up the 310 under a special waiver, would you do it?

I wouldn't. I want an aviation grade fuel, tested, water drained, filtered, whatever. It's just not worth finding out the hard way I created a problem to save a few bucks.
 
Cmercado said:
Well..... There is the "Island Time" factor involved........ But the issue is that in Puerto Rico and the USVI we are regulated by the FAA.. The islands are a US territory... In other islands probably is another story..
Click to expand...

My suspicion is that you see significantly less stringent enforcement there than in the lower 48, probably due a combination of will power and manpower.
 
Last edited:
Believe it or not before STC for auto fuel there were pilots burning auto fuel. Before AVgas there was auto fuel.
 
You must log in or register to reply here.
Back
Top