Gas Octane??

[1wildthing]

Oh yeah -- on the methanol thing: I've seen on the labels that you should NEVER use methanol (methyl alcohol or wood alcohol) in a 2-stroke engine. I don't know why but I suspect that methanol is such a strong solvent that it could theoretically wash away the oil on the cylinder walls and cause a seize.

I think the reason that you have seen this is that alchohol (methanol or ethanol) will cause your motor to run lean - which can kill a two stroke. Even though the alchohol has a higher octane rating, it carries less energy per volume. Don't remeber the specific gravities and such, but In order to run alky in a motor you need much larger jets in your carb, or injectors in order to deliver enough fuel.

 

[Chainsaw Master]

Hmm I'm not a chemist, nor a fuel technician, but I've ran saws alot using alot of different gasolines. What I've noticed tho is the higher the octane the more power the saw puts out, just the other day the saw was filled with my buddies 87 octane, and was cutting ok, I refilled just before it ran out. When the saw burned out his 87 gas,that was in the lines & carb and started burning the 93 octane, it was like shifting gears, and the saw perked up, and cut alot better.

I heard somewhere that gas companies put more alcohol in the wintrer , than in the summer, because it dosen't evaporate off in the cold. Alcohol messes up carb diaphrams and lines when it sets in them, hotsaws that run on alcohol, have gas run through them before parking them for this reason. Alcohol in gas raises the octane, so burning an alcohol mix is no problem, just the leaving it set in the saw part does. One last one if you mix a pint of alcohol and a pint of water....you don't get two pints of liquid, but like 1 3/4 pints of liquid.....try it and see.

 

[BostonBull]

Hmm I'm not a chemist, nor a fuel technician, but I've ran saws alot using alot of different gasolines. What I've noticed tho is the higher the octane the more power the saw puts out, just the other day the saw was filled with my buddies 87 octane, and was cutting ok, I refilled just before it ran out. When the saw burned out his 87 gas,that was in the lines & carb and started burning the 93 octane, it was like shifting gears, and the saw perked up, and cut alot better.

This is because most saws are MADE to run on high octane fuels. Usually 89 or higher. It is like putting 87 in a Vette or Porsce..it will knock and ping.

 

[bwalker]

MTBE doped fuel is much preffered to Ethanol doped fuel. The only reason MTBE is being banned is because of politics(think corn lobby) and the fact that it has high motilllity and a foul odor/taste. Toxicity has never been proven to be a issue with mtbe.
Iso propyl alchol is the best dry gas. Even though methnaol is sold as dry gas it sucks in practice. It will draw water vapour right out of the atmosphere, through the wall of a gas tank, etc untilly ou get a massive amount of water in the bottom of the tank. When methanol and water mix they always seperate from the gasoline and build up at the bottom of the tank. Iso on the other hand will bond to the water and not drop out of suspension,allowing the water to be ran through the engine and combusted. I know this because I opperate a fleet of outboard motors and in the spring time water in the fuel is a fact of life.
As for octane. Use premium as it is cheep insurance that protects against detonation and pre ignition, which can lead to seizures/scuffing.

 

[BostonBull]

MTBE doped fuel is much preffered to Ethanol doped fuel. The only reason MTBE is being banned is because of politics(think corn lobby) and the fact that it has high motilllity and a foul odor/taste. Toxicity has never been proven to be a issue with mtbe.

Interesting I was told it was tasteless and odorless, and that mixedwith water you couldnt tell it was even in it.........damn teacher!

 

[bwalker]

Ethanol is tasteless and oderless, but MTBE has a very strong flavor and odor. Thats why its a big deal once it gets into the water supply.
BTW there is nothign better than the smell Of Phillips 66 MTBE based race fuel.:rockn:

 

[kevinj]

Octane follow up !!!

HOLY COW ! : I didn't this thread would get so discriptive, and complex!!
Seems there's a lot of things going on out there, that maybe, most people dont know about. As far as the different grades.
Am I the only one ?
So is Midgrade the choice??

 

[SRT-Tech]

Cool fact we learned in Silver school that most of you gurus already know I am sure.

The E-85 gas CANT be run in saws. Physically. The Ethanol content is so high, and ethanol is so thick it wont fit through the passages and jets in the carbs we use on saws.

Takea small graduated beaker with a lid on it and pour some 2 stroke MIXED E-85 ga in it and let it seperate. It will be gas on top, then ethanol then water. The Ethanol looks like a giant snot/lungy. Very gross to look at. When in carbs it comes out of the passages, welch plugs, and jets in long gross strings.

One more cool fact....

You know the test pastes such as Aqua Check to check for water in fuel? It wont read correctly if using Stihl Ultra oil. Something about how the Oil is made makes it test negative even if there is water. I forget the whole story but...

HUH?????? ethanol stringy? thick? you sure that was ethanol you saw?? cuz i'm looking at a 20 liter can of 99.99% Pure Ethanol and the Ethanol is extremely thin and liquidy, and evaporates quickly.

 

[Chainsaw Master]

Ethanol is tasteless and oderless, but MTBE has a very strong flavor and odor. Thats why its a big deal once it gets into the water supply.
BTW there is nothign better than the smell Of Phillips 66 MTBE based race fuel.:rockn:

When running my saw...I've noticed that some gas has a sickly sweet smell, so strong as to even taste it.....is this MTBE?

 

[BostonBull]

HUH?????? ethanol stringy? thick? you sure that was ethanol you saw?? cuz i'm looking at a 20 liter can of 99.99% Pure Ethanol and the Ethanol is extremely thin and liquidy, and evaporates quickly.

That is what they told us at Silver School for Stihl. They showed us carbs that people ran E-85 through and then showed us the seperated fuel in a beaker with a cap......maybe we were duped? Like I said most of this knowledge is from memory, recent classes, and books.

 

[SRT-Tech]

That is what they told us at Silver School for Stihl. They showed us carbs that people ran E-85 through and then showed us the seperated fuel in a beaker with a cap......maybe we were duped? Like I said most of this knowledge is from memory, recent classes, and books.

fair enough, but how come i can run 20 - 30% ethanol in my gas for my truck (for the past 5 years) and i have had ZERO issues with the carb, seals, combustion chambers, piston tops, fuel lines etc???

not stirring up doodoo, just genuinely curious.......

 

[BostonBull]

fair enough, but how come i can run 20 - 30% ethanol in my gas for my truck (for the past 5 years) and i have had ZERO issues with the carb, seals, combustion chambers, piston tops, fuel lines etc???

not stirring up doodoo, just genuinely curious.......

Excellent question....I dont have any idea. Are the passages in the carbs different? I would have to believe so. I was told cars wih the special yellow fuel caps that run E-85 have gigantic fuel injectors as compare to a regular car. There has also been problems of Marine engines....2 and four stroke...having issues with the Ethanol in the fuel.

 

[bwalker]

When running my saw...I've noticed that some gas has a sickly sweet smell, so strong as to even taste it.....is this MTBE?

It could be, but RFG/oxygenated fuel is rare in MI so I dont know. And I cant imagine that Barton City is in a non atainment area.

 

[bwalker]

That is what they told us at Silver School for Stihl.

if they told you MTBE is tasteless and odorless and that Ethanol was thick I think its safe to say the guy teaching the class was a complete idiot.:hmm3grin2orange:
No wonder there are so many misinformed dealers out there.

 

[bwalker]

http://www.epa.gov/mtbe/water.htm

How do I know if I have MTBE in my water?

It is possible your water would taste and/or smell like turpentine if MTBE is present at levels around or above 20-40 ppb (some people may detect it at even lower levels). Though you cannot currently purchase a home testing kit, you can determine if your water contains MTBE the following ways. If your drinking water is supplied by a public water system, you can contact the system directly and ask whether they monitor for MTBE and what levels, if any, have been detected. In 2001, most public water systems will be required to monitor for MTBE. If you have a private well, you may want to have your well water tested. Your local health department may be able to tell you if MTBE has been found in water in your area. If you want to get your water tested, call the Safe Drinking Water Hotline (800-426-4791) or go to http://www.epa.gov/safewater/faq/sco.html to get the phone number for the office in your state that certifies drinking water laboratories.

http://www.braytonlaw.com/practiceareas/mtbe.htm

MTBE is a synthetic, volatile, colorless ether with an unpleasant turpentine–like taste and odor. These properties can make contaminated drinking water unacceptable to the public. Studies have analyzed the concentrations of MTBE in drinking water at which people can detect the odor or taste of the chemical. The results varied. Some who are sensitive to odors can detect very low concentrations of MTBE, and others do not taste or smell the chemical even at much higher concentrations. Moreover, the presence or absence of other natural or water treatment chemicals can mask or reveal MTBE taste or odor.

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

 

[PES+]

Hokay

Let me be brief and as non technical as I can. MBTE did NOT start out as an octane boost but was originally an oxogynate fuel hence the O at the end of the (C5H12O) versus the H at the end of the (CH3OH). This is a fact and I care little for current gasoline crap science takking to the contrary I lived through the conversion from leaded fuel and the reason for the adaptation and modifying was the local refional requirements for "Low emission fuels" so the ether currently used is or was an oxygenate to "clean up" emissions the other thing this additive does is it allows refiners to use much lower quality base gasoline stocks. The problem which I explained and the reason I call it methanol is that the conversion to MBTE from methanol and isobutane and or propane is not permanent and degrades rather rapidly and guess what happens when the gas volitiles leave the fuel mix? What is left?

Boston Bull I have no doubt that Stihl confused Butyl alcohol (which is thick) with ethyl alcohol (which is one of the thinnest)

 

[bwalker]

does is it allows refiners to use much lower quality base gasoline stocks.

Which is where the high octane comes in...
RFG are crap no doubt, but MTBE can be the basis for some pretty outstanding race fuels.

 

[retoocs555]

Would mix oil dissolve in straight ethanol or seperate?

 

[PES+]

Not in this country

I have yet to see an MBTE only fortified racing fuel in the USA and to my knowledge very little is used in aviation gasolines. I do not doubt that higher quailty stocks as base are refined in europe. MBTE stinks it has a definite sour smell. Good racing fuels here are still lead based and have a sweet aromatic smell. EBTE is used in some and it also has a sweet odor to it but it still attracts water just like it's base.

Ethanol is pretty much impossible to keep free of water because it draws water vapor directly out of the air.

 

[bwalker]

PEST, the reason RFG gas breaks down so fast has to do with the crappy cracked base stocks used and not the MTBE. MTBE is really stable/persistant, that's why its a pain in the azz once it gets into the water supply.
Alcohol based RFG are really bad as not only do the have the crappy base stocks, but they also attract water. lets of metal tanks rust out from this and its also the reson you have problems with plastic and rubber parts in carbs(although most fuel parts have been reformulated).