auto gas vs av gas

[Tom-D]

Marvel Mystery Oil is interesting stuff. I use it on squealing air conditioners down here in the salt air, and it's amazing. One shot of the stuff on the shaft, and no more squeak.

I've got one that was shrieking when we bought the hotel 16 months ago. One shot of MMO, and it's never made another peep.

Any good lube oil would do the same thing.

research what oil of wintergreen is, and you will know why MMO works and smells like it does.

 

[Dan Thomas]

Gotta link to verify?

never heard that before.

All I could find that it was a guy named Burt Pierce who founded Marvel Oil in 1923 to make the stuff for cleaning clogged fuel jets in carbs. Fuel was pretty sketchy back then.

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

Another site says it's mostly petroleum distillate, the same solvent found in so many of the little bottles and cans of additives for cleaning injectors, loosening stuck lifters, and so on. A do-it-all thing.

Dan

 

[MSPAviator]

I wouldn't put Marvel Mystery Oil in my gas tank. Airplane, car, or lawnmower.

 

[Tom-D]

If I had a link I wouldn't know how to post it! I am not very computer savy but I will try to find an article for you. The Air Force used to by it by the drum for the the old radial engine planes like the Skyraider and T-28.

Got a reference for that ?

If they did it would have a mil-Spec number which it doesn't.

 

[COFlyBoy]

If you had 2 petree dishes, one with diesel in it, and the other with 100LL in it and you ignited each which would burn faster?

yet which will detonate first in use?


It's all in the manner the fuel is used.

Gasoline will burn faster (lower boiling point)
Diesel will detonate first (Much lower RON/MON rating ~25 diesel, ~100 Avgas)
Diesel will release more energy (128,000 BTU/US gal diesel, 115,000 BTU/US gal gas)

 

[AEROBAT]

I had a conversation the other evening with a guy who runs MMO in his fuel.

he must take a 709 ride with FSDO pilot pilot examiner, the Check ride pilot sniffed the tanks and refused to ride with him.

the check ride pilot said they were not allowed to ride in any aircraft that had auto fuel (STC) or any unauthorized additives in the system.

So now the guy is taking training in a rental ($1000) to be allowed to use the rental to take the examiner for the 709 ride.

If he had a problem with a few ounces of MMO the check pilot would probably have a coronary if he watched guys filling their Air Tractors and turbine helicopters with diesel like they used to do here when diesel was cheap. Now Jet A is cheaper than diesel and my son is burning it in his tractor.

 

[timwinters]

The 150's O-200-A is certified for 80 octane fuel. Try to find any Mogas that has such a low octane rating.

Dan

Avgas and mogas use different scales. 80 octane avgas is essentially the same as 87-89 octane mogas.

Look for the date the auto gas STC s were issued to EAA and Petersen, you'll see at that time there was lead in auto fuel

It was 1982 before The FAA changed their policy to even consider allowing mogas so I don't think this is an accurate statement. Leaded gas was still available in 1982 but it was quickly disappearing and all new cars had been burning unleaded for 7 years by then.

 

[Tom-D]

Avgas and mogas use different scales. 80 octane avgas is essentially the same as 87-89 octane mogas.



It was 1982 before The FAA changed their policy to even consider allowing mogas so I don't think this is an accurate statement. Leaded gas was still available in 1982 but it was quickly disappearing and all new cars had been burning unleaded for 7 years by then.

The testing occurred years before certification.

 

[TripleZ]

The testing occurred years before certification.

Yup, We've been testing E15 and E20 fuels for over a year now....... not out at the pumps yet. People might start seeing E15 Mogas at the end of this year.

Avgas and mogas use different scales. 80 octane avgas is essentially the same as 87-89 octane mogas.

Heh, I was going to dispute this, but instead learned something today. I thought Lean/Rich mixture Octane ratings were only used for reference fuels in development or research engines. Never thought they used it for Avgas as well.

http://www.shell.com/home/content/aviation/aeroshell/technical_talk/techart12_30071515.html

Octane rating is a measure of how resistant a fuel is to detonation or "pinking"; the higher the Octane rating, the more the fuel / air mixture can be compressed without detonation happening. To make this clear, octane rating is not a measure of the amount energy in the fuel, but is a measure of its resistance to detonation.


The advantage or higher octane fuels is that a higher compression ratio or supercharging ratio can be used, which then leads to a higher engine cycle efficiency, which in turn means more power output for a given fuel burn. However, to confuse things further, there are four principal ways to measure Octane rating, RON, MON, Lean Mixture and Rich Mixture ratings.
Road fuels tend to be measured on a RON scale, for which unleaded fuels tend to be 95 - 98 RON but are only 85 - 87 MON.

Avgas is measured on Lean Mixture (similar to MON) but also has a Rich Mixture Octane rating.
The Lean Mixture rating is 100 octane (15 octane higher than the comparable 85 MON for unleaded Mogas) but Avgas also has a Rich Mixture rating of 130 which allows higher supercharger boost pressures to be used without detonation occurring. This is particularly a problem when using high power settings at low altitude, for example during take off.

 

[timwinters]

The testing occurred years before certification.

Now that's funny right there!

You're proven to be full of sh*t on you're original postulation so, in an act of desparation, you change to a new premise and hope no one notices.

That's rich.

 

[AEROBAT]

Now that's funny right there!

You're proven to be full of sh*t on you're original postulation so, in an act of desparation, you change to a new premise and hope no one notices.

That's rich.

Don't worry, next he will be asking for a link.

 

[RotorAndWing]

Now that's funny right there!

You're proven to be full of sh*t on you're original postulation so, in an act of desparation, you change to a new premise and hope no one notices.

That's rich.

 

[Greg Bockelman]

Out of curiosity, if the current blend of non ethanol Mo Gas does not conform to the specifications that the FAA approved, why has the STC not been rescinded?

 

[kyleb]

Out of curiosity, if the current blend of non ethanol Mo Gas does not conform to the specifications that the FAA approved, why has the STC not been rescinded?

I suspect because the STC is still valid. It is just the pilot's responsibility to find fuel that meets the STC's requirements. I've never read the fuel spec part of a mogas STC. I wonder how much specificity it has?

 

[Tom-D]

Don't worry, next he will be asking for a link.

No, I'll give ya the link http://www.autofuelstc.com/autofuelstc/pa/Contact_.html ask the right people, get the right info before ya say any one id full of .......

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

Phase-out

In most industrialized countries, TEL was discontinued in the late 20th century because of concerns over air and soil pollution (e.g., the areas around roads) and the accumulative neurotoxicity of lead. The use of TEL as a fuel additive spoils catalytic converters, which were introduced in the 1970s to meet tightening emissions regulations. The need for TEL was lessened by several advances in automotive engineering and petroleum chemistry. Lower oil prices promoted the development of low compression engines that were less sensitive to gasoline quality. Other antiknock additives of varying toxicity, such as MMT, MTBE, and ETBE, and safer methods for making higher octane blending stocks such as reformate and iso-octane, reduced the need for TEL.

Just because the Cat converters were introduced in the 70 doesn't mean there wasn't any leaded fuels around well into the 90s

 

[Tom-D]

Here is another good reference to when all the lead was gone and what replaced it.

http://www.chemcases.com/converter/converter-21.htm

 

[Tom-D]

http://www.eaa.org/autofuel/

Testing started in 64, and the STC was issued in 82

EAA began testing and evaluating alternate fuels for aircraft piston engines in 1964. These included not only automobile gasoline, but also ethanol. In 1982, EAA successfully changed FAA policy to consider the use of automobile gasoline in aircraft. The EAA type certificate program resulted in an FAA Supplemental Type Certificate (STC) being issued for the use of automobile gasoline, rather than aviation gasoline, in the Cessna 150 aircraft, powered by a Continental O-200 engine. The first pilot to legally fly in an aircraft with automobile gasoline was, then FAA Administrator, Lynn Helms. Since then, more than 40,000 STC's have been issued.

end quote

and lead didn't go away until the 90s who is full of ......

 

[timwinters]

Nahhh…you should know me better than that. I try not to get into protracted arguments, especially with moving targets. I just say what I got to say and move along.

 

[dmac5356]

The STC's specifically permit leaded and unleaded mogas that meets ASTM D439. D4814 is an evolution of D439, but adds specs for oxygenates. Ethanol is the only current EPA approved oxygenate for cars (but NOT approved for aircraft, of course).

100LL avgas has 120,200 BTU/gal while mogas has 125,000 BTU/gal... so the statements that mogas contains less energy is incorrect.

I have used mogas in a Cherokee, Bonanza, and Debonair over the past 27 years with great success. No oil sludge, sticking valves, or fouled plugs. YMMV

 

[Tom-D]

T
100LL avgas has 120,200 BTU/gal while mogas has 125,000 BTU/gal... so the statements that mogas contains less energy is incorrect.

Where did you get those numbers?

the 439 spec was leaded fuel withdrawn in 1990.

How can you remove 20% of the gas stock, and replace it with a product that has less BTUs per pound and expect it to have more BTUs per pound?

Some thing is not making common sense.

 

[Dean]

I made my own fuel tank and would buy 91 or 93 Oct from the local marina. We also had a few gas stations near the lake that would carry ethanol free fuel as well. I used a 250 gallon tank and a hand pump I purchased at a farm supply store. Had the tank on a small trailer so I could roll it around the hangar. Worked great and cut my fuel cost in half.