A question of fuel

[Ward Barnes]

Howdy: 

I have the choice of fuels to use in my 2007 MS 390.  I can use either 87, 89, or 92 octane gas/oil with 10 percent ethanol or 87 octane real gas (no ethanol).  I have been using the 92 octane w/ethanol for several years on the advice of my dealer who said that there is a 30 degree drop in head temperature for each step up in octane rating.  The owners manual calls for 89 octane, but, does not mention the ethanol stuff.  I do not currently have a source for the higher octane non-ethanol gas.  Now I am wondering, which would be best 89 or 92 octane with ethanol or 87 octane without ethanol?

God Bless, Ward.

[albirk]

I run the 87 with fuel treatment saws,weedeat,leaf blower all take the same mix

[T Welsh]

Ward, all saw,s will run lower grade fuels with out issue,s. The problem with the ethanol added in is when you let the fuel in the tanks for an extended period of time,it will erode seals and rubber pretty fast. we never had a problem with fuel lines and impluse hoses in the last 30 years and in the last 5 to 8 years I have had to change out at  least 3 or 4 hoses because of degradation. Maybe dump the gas from the tank when done using saw for firewood season and run it till it dies and put it away dry.we run our saw,s everyday and have no issue,s with gas,we also go through 5 gallons of mix a week. I tell my brother to do this to his saw after using it,because he only uses it for about two weeks out of the year. Tim

[Al_Smith]

The rascals make us use ethanol blended gasoline under the guise of less polutants etc while all the while knowing it takes 40 percent more alcohol than gasoline to produce the same power .

Ethanol is the greastest hoax ever pulled on the American public since Billy SolEstes and the Hunt brothers .About 80 percent of all ethanol producing plants go bankrupt within two years of operation and are bought up by several big conglomerants for pennys on the dollar .

[Al_Smith]

Now that I've whined about high tech moonshine to the subject .

About the only option left for high octane non ethanol gasoline is aviation fuel .Not all airports will sell the stuff though ,depends .

Here of late the carb kits in addition to OEM Stihl crankshaft seals are made of a material which is more robust to degradation than the older Buna-n material which was used for decades before .

I might get a couple years between carb rebuilds but that's about it .On that though I've gotten real good at rebuilding carbs because I've done so many .

[drilldog]

Try checking with all of the gas stations in your area. Even ask if they know of any ethanol free gas available or if they ever intend on getting it. There is a station in my area (5 blocks from my house) that started carrying regular ethanol free gas and just recently started carrying premium ethanol free. Maybe you will get lucky and a station in your area will see that there is a market for it. The mentioned station is always busy with 4 wheelers, snowmobiles, lawn mowers, etc.

[Stihlnorm]

the higher the octane the better to a point. basically buys you more time in storage. you want to stay above 89(ron)

the main issues with ethanol are as follows...

Problem #1 Debris in fuel - Ethanol gums rapidly in the tank and fuel delivery system as the fuel sits. However, ethanol is also a powerful solvent that will strip away those deposits and introduce those particles back into the fuel stream. This leads to clogged filters, injectors and carbs.

 

Problem #2 Excessive water in fuel and phase separation – Ethanol attracts moisture from the atmosphere, forming an ethanol/water solution mixed in the gasoline. Ethanol fuels will naturally hold .5% water in suspension, but when water levels exceed this threshold, or when the fuel cools significantly, the ethanol/water drops out of suspension. This is phase separation. Ethanol provides a significant amount of the fuels octane, so when the ethanol/water solution drops to the bottom of the tank, the remaining fuel is left without enough octane to properly operate the engine. Additionally, the ethanol/water solution can be partially combustible, which also leads to engine damage.

 

Problem #3 Ethanol breaks down quickly – As ethanol evaporates the fuel loses octane and becomes stale quickly and because ethanol blended fuels rely so heavily on the ethanol to boost the octane rating of the fuel the results are numerous. This causes hard starting, pinging ( pre ignition ), engine knock ( detonation ), loss of power and engine damage.

 

Problem #4 Ethanol causes poor performance and decreased fuel economy – Ethanol does not produce as much energy as traditional fuel. This results in inefficient combustion, poor throttle response and poor fuel economy.

 

[John Mc]

Stihlnorm gies a good summary on ethanol's problems. To add to his points a bit:

the higher the octane the better to a point. basically buys you more time in storage. you want to stay above 89(ron)

Once you get above the octane rating required to avoid detonation (which varies with different engines and operating conditions), you don't gain anything by going higher.

The one exception to this is that since fuel will tend to lose octane rating over time as various components of the fuel evaporate off, starting with a higher octane than absolutely needed to run the engine safely gives you some extra margin or a bit of extra shelf life.

Ethanol provides a significant amount of the fuels octane, so when the ethanol/water solution drops to the bottom of the tank, the remaining fuel is left without enough octane to properly operate the engine.

Specifically, the ethanol an an E10 blend (10% ethanol) adds about 3 or 4 points of octane rating. So for example the "pure gas" gas blend stock used to make 91-93 octane E10 blend would have only about 89 octane before blending. (wouldn't it be great if they'd just sell you the blend stock?)

Additionally, the ethanol/water solution can be partially combustible, which also leads to engine damage.

That ethanol/water mix is also corrosive.

Problem #4 Ethanol causes poor performance and decreased fuel economy – Ethanol does not produce as much energy as traditional fuel. This results in inefficient combustion, poor throttle response and poor fuel economy.

I've checked our two family cars extensively (2002 and 2004 models - so they were made well after E10 gas became common). On one, I get about 10% worse gas mileage when running E10 gas. On the other, I get 12-13% worse mileage with E10.

In the summer, you can find premium ethanol-free gas here in VT, if you look around for it. Since that only costs about 7% more than the E10 regular gas, I'm ahead of the game buying the premium E0 gas.

Some of the biggest problems with ethanol tend to relate to how long it's been sitting. (It takes time for it to absorb enough moisture out of the air to cause phase separation. It also takes time for ethanol and other components to evaporate off, lowering the octane rating.) So guys who buy fresh fuel, and go through it quickly tend to have less problems with it than folks who may buy some, use a bit, and let the rest sit a bit. Weekend warriors (like me) need to be more careful about keeping an eye on what shape their fuel is in.

[Norm]

I've been running ethanol blended fuel for 20 years with no more problems than the unblended I bought before. Nice to see the fuel makers found a whipping boy for their crappy gas though.

[Bill Gaiche]

I run premium fuel in all my 2 cycle engines and can say that it has worked fine for me. bg

[mad murdock]

Norm, I don't doubt you have had good results with blended fuel. Ethanol blends by being mandated under the guise of "cleaner burning" is nothing more than a thinly veiled excuse to get more tax dollars without having to "pay " for it politically.  Physical properties of fuels show the difference in BTU's of given quantities of any fuel. You can't get more energy released from a fuel with less btu potential, in my opinion.  You are probably more diligent than the average bear in keeping up on your preventative maintenance to not have had the problems that ethanol blends can incur.

[John Mc]

The majority of ethanol-related problems can be solved by buying fresh fuel, and using it up quickly. Don't store it in a small engine's fuel tank and don't leave it in the carb for any length of time.

Yes, there are those engines that just plain don't like ethanol (my old garden tractor is one of them). There are those that need an older fuel line or diaphragm replaced with something ethanol resistant. But if you are someone who turns over your fuel regularly and quickly, you'll avoid a lot of the problems.

You will see a loss in gas mileage in vehicles burning E10 gas. Ethanol has about 2/3 the energy content of gas, so in theory, if E10 burns with the same efficiency that gas does, you should see about a 3.3% reduction in MPG (since only 10% of your fuel is "missing" 33% of the energy of gas). For some reason, I see a drop that ranges from 3 to 4 times that amount -- and this is on relatively modern cars (2002 and 2004 model years). I can only conclude that there is more going on here than just the straight energy content of the fuel.

Getting back to chainsaws: I have noticed a difference in tuning needed to run E10 blends, as compared to "straight gas". If I'm set for pure gas, when I put the E10 in, I'll be running a bit lean. In he summer, when both E0 and E10 are available around here, I'll sometimes tune for E10 when I think there's a chance I'll be switching back and forth -- that way, the worst case is I'm running a bit rich when I'm on E0. (The better way would be to stick with one type, or tune more frequently, but sometimes that just doesn't happen when I'm working with the land co-op and we're sharing fuel. Generally, I tend to burn only my own fuel, but you never know...)

The chainsaw shops with whom I've spoken have seen an increase in "toasted" cylinders as E10 has become more widespread. Some have also noticed more frequent corrosion. Hard to say how much of this is from the rash of new chainsaw owners who started burning more wood as oil and gas prices shot up, and how much of this is from gas. However, Just last week, I ran into two friends who've been woodburners for 25+ years who each just burnt up their chainsaws. (We did have one gas station that got a bad load of fuel, but that's a 40 minute drive from us, and neither of them bought fuel there. There have been no other reports of bad loads at stations closer by -- looks like that one was just a fluke.)

And I see that once again, I got off on a long rambling rant. I meant to just rite the first two paragraphs, but for some reason, the whole ethanol issue just punches my buttons...

John Mc

[Al_Smith]

The ethanol situation has caused problems not only on two cycle engines but just nearly every engine that uses it .

The auto manufacuers had to go to more robust materials for seals because of it .The diaphragm fuel pumps on lawn mower type engines only last about 5 years and all kinds of problems .

Now here you go about lawnmower engines .The "pulsa-jet" carbs which Briggs uses is just a float carb with a diaphragm pump . Many times the repair shops just stick a new carb on them to the tune of 150 bucks a pop when all it is is bad pump innards .The complete rebuild kit for those pumps is 8 bucks through Baileys .

Being a tight wad I just buy the diaphragms for under a buck a pop which is two dollars per carb .---Al the miser ---

[Gary_C]

I will echo what Norm has said. But neither of us has an agenda to blame ethanol for all the problems with running small engines. Could it be that chainsaw manufacturers are making saws that are less reliable and more prone to problems?

And I couldn't abuse my saw any more. Since I do essentially all my sawing with a harvester, my chainsaw lays in the back of the pickup just about all the time. I can and do go months without running it and when I need it, it has the last gas I put in it and yet it starts right off. I've never had it in the shop but once and that was to replace the rusted out muffler. So I don't have the time nor the desire to blame something for any problems with the saw.

Last winter I lived out in the woods in far below zero weather and relied on a new Honda generator for power. One morning it -30 or more and the generator was not running well. So I took it back to the place I bought it to see what was wrong. And the first thing the service man tried to do was blame it on ethanol in the gas. Told me I should get a can of Heat and put in the gas. And I said to him "so the problem is ethanol in the gas and the solution is to get a jug of alcohol and put in the tank?" He though a minute and said "you're right." So he brought it inside and let it thaw out. Turns out the problem there was frost forming on the throttle plate and the air inlet to the carb. So the solution was to stay home when it gets that cold. The generator is made to run on any amount of ethanol in the gas and it does just fine. I always buy regular gas with whatever ethanol it contains and still no problems.

[Paul_H]

What is this "agenda" BS thrown around here lately whenever it might be suggested that ethanol might be a factor in some issues with small engines? I don't agree that ethanol is evil but lets not pretend that it doesn't cause some problems that need to be discussed.
I know Stihlnorm personally and he knows what he is talking about.He wasn't railing against corn,just issues with ethanol in engines that should be kept in mind when using it or storing it.

[Gary_C]

Paul, since I was the one using the word "agenda" I will respond with this.

Ethanol is the greastest hoax ever pulled on the American public since Billy SolEstes and the Hunt brothers .About 80 percent of all ethanol producing plants go bankrupt within two years of operation and are bought up by several big conglomerants for pennys on the dollar .

I have never said that ethanol nor gasoline for that matter does not cause problems in small engines. What I have said is that blaming ethanol for all the problems in running small engines is not right. Here from Wiki is a good description of what the blend of organic compounds called gasoline contains.

The various refinery streams blended to make gasoline have different characteristics. Some important streams are:

straight-run gasoline is distilled directly from crude oil. Once the leading source of fuel, its low octane rating required lead additives. It is low in aromatics (depending on the grade of crude oil), containing some naphthenes (cycloalkanes) and no olefins. About 0-20% of gasoline is derived from this material, in part because the supply of this fraction is insufficient and its RON is too low.
reformate, produced in a catalytic reformer with a high octane rating and high aromatic content, and very low olefins (alkenes). Most of the benzene, toluene, and xylene (the so-called BTX) are more valuable as chemical feedstocks and are thus removed to some extent.
cat cracked gasoline or cat cracked naphtha, produced from a catalytic cracker, with a moderate octane rating, high olefins (alkene) content, and moderate aromatics level.
hydrocrackate (heavy, mid, and light) produced from a hydrocracker, with medium to low octane rating and moderate aromatic levels.
alkylate is produced in an alkylation unit, involving the addition of isobutane to alkenes giving branched chains but low aromatics.
isomerate is obtained by isomerizing low octane straight run gasoline to iso-parafins (like isooctane).
The terms above are the jargon used in the oil industry but terminology varies.

Overall, a typical gasoline is predominantly a mixture of paraffins (alkanes), naphthenes (cycloalkanes), and olefins (alkenes). The actual ratio depends on:

the oil refinery that makes the gasoline, as not all refineries have the same set of processing units;
crude oil feed used by the refinery;
the grade of gasoline, in particular, the octane rating.
Currently, many countries set limits on gasoline aromatics in general, benzene in particular, and olefin (alkene) content. Such regulations led to increasing preference for high octane pure paraffin (alkane) components, such as alkylate, and is forcing refineries to add processing units to reduce benzene content.

Gasoline can also contain other organic compounds, such as organic ethers (deliberately added), plus small levels of contaminants, in particular organosulfur compounds, but these are usually removed at the refinery.

So blaming ethanol for all the ills of running small engines is just not right. And that is what Norm said also.

Nice to see the fuel makers found a whipping boy for their crappy gas though.

[Paul_H]

Gary,
Al is a self professed bar room lawyer so most wouldn't take the post you quoted him too seriously but I doubt that he has any agenda other than letting off a bit of steam.
I like the ideas of alternate fuels and have plans and parts purchased to make ethanol one day soon.
Stihlnorm and other technicians like him don't look to politics but to solving problems related to fuels whatever they may be and to me it's worth listening to.

[Ward Barnes]

Howdy Folks:

A local marina is now selling 93 octane without Ethanol to any customer, not just the boaters.  The saw seems to like it and the price per gallon is just a few cents above what the 92 E10 is selling for.

During the boating season they just about don't shut their pumps off.  Outboards don't like E10.

God Bless, Ward and Mary.

[John Mc]

Hey, I'll admit, I do tend to go overboard. I don't have an "agenda" against ethanol. I have an agenda against things that don't work well, or don't make sense, particularly if they are also being heavily subsidized by tax dollars (and yes, I'm well aware of the fact that just about every form of energy used in the US is subsidized in some way - probably one of the reasons we're such energy hogs in the US as compared to many other countries.). I grew up on a farm in "corn country" (maybe not quite to the extent that Iowa is corn country, but it was - and still is - a major crop for the farmers in that area).

What really bugs me is that it receives a huge subsidy, supposedly to help foster our independence from imported oil. I don't see how an additive that causes a drop of anywhere from 9 to 13% in Fuel economy when blended at 10% with gas is accomplishing anything on that front. (Mileage as tracked in detail on four different vehicles that I've followed, including some "blind" tests.)

The ethanol mandate adopted by our friends in Washington does not actually specify a percent to blend (or even a percent of total fuel sales). It specifies a straight gallon amount to be sold each year (and increasing year-over-year). The original intent was that it would spur the market for E85 fuel. In that, it's failed miserably. In all of my travels, I've only seen one E85 pump in my life.

If E85 were widely available (and at a somewhat competitive price), my next vehicle would be one able to run it, and I'd buy that fuel willingly (at least for use in my cars). Widespread use of E85 would in fact reduce our dependence on foreign oil. E85 is in fact more stable than E10 blends, so shelf life would not be as much of an issue as it is now.

John Mc

[John Mc]

A local marina is now selling 93 octane without Ethanol to any customer, not just the boaters.  The saw seems to like it and the price per gallon is just a few cents above what the 92 E10 is selling for.

Nice that you can get it. It's only available in the summertime around here.