Mid grade Gas for stock Saws or lightly modded??

[RiverRat2]

Anybody have any thoughts about it and how long should you keep it once youve mixed it????

 

[computeruser]

I only run premium, 93 octane. I try to use my mix up within 2 weeks, but sometimes go as long as a month. Never had any bad fuel problems so far as I can tell - saws, blowers, string trimmers, and hedge trimmers have always been very happy with the fuel they get fed. I mix in small batches, usually 2 gallons at a time. If I have excess left over, I off-load it on family and neighbors and re-mix the next time I have a cutting session planned.

 

[Rydaddy]

93 octane (premium)

I have always used premium octane just "because." Ran out this summer after dropping 3 cherry trees in a friends yard and had to finish up with some 87 octane. I didn't even think anything of it, but later on I mentioned to him that my saws (using a 357xp and MS361 that day) seemed to be runnin poorly. Went and got more 93 octane, and they woke back up. May not matter in non-pro saws, but those two sure didn't enjoy the 87.

 

[RiverRat2]

I never run Regular, But I do use Mid grade 89 octane in my stock saws and when it gets about a month old I just pour it into my Truck. I do run 93 in my modded saws and just mix a gallon @ at a time. Thanks for the reply

 

[ciscoguy01]

266

Anybody have any thoughts about it and how long should you keep it once youve mixed it????

How did you mod your 266xp eh? For gas, eh, I never worry about it. All the newer oils have preserves in them to keep it fresh. Gas is good for several months w/out any preserves. Think about the smaller gas stations, they keep theirs in the tanks for months. I did start using the 93 though, that seemed to make a large improvement on performance in my saws. Gas companies say that storage of gas is 1 year. These dudes think gas goes bad in a couple months are paranoid. Link below for a dude's test. Found all kind of info on this on a google search... I'm not knocking anyone, but it's kinda the same thing. Everyone has had a friend that won't let you lean on their car, or put their shoes on the floor of their car. It's just what you prefer to do guy. Scientifically, if stored correctly, gas can last for years and years...

http://www.alpharubicon.com/altenergy/gaslifepal.htm

Chevron's take on gasoline storage/life...

http://www.chevron.com/products/prodserv/fuels/bulletin/longterm_gasoline/

 

[RiverRat2]

266 mod

just cleaned the flashing off of the piston and opened the exhaust to match the muffler and cleaned up the intake & transferports, nothing radical but it sure woke it up

 

[Chainsaw Master]

"Chevron gasoline can be stored for a year without deterioration when the storage conditions are good -- a tightly closed container and moderate temperatures."

Quoted from the link from above......With the key words being tightly closed container. The plastic jugs with the clip caps and such, let all the lighter, higher octane gases, evaporate off the gas, in as little as a few days, in warm weather. The best, more explosive gases, evaporate first.
I store & carry all my gas in sealed metal cans to stop the evaporation.

 

[ciscoguy01]

Hmm

just cleaned the flashing off of the piston and opened the exhaust to match the muffler and cleaned up the intake & transferports, nothing radical but it sure woke it up

Wowzer dude. I'm happy with mine stock, I guess I'd be ecstatic at one like that. Thanks for the info dude.

 

[SRT-Tech]

i store my fuel (after mixing) in these:

i generally mix up ten liters of fuel and then pour it into the fuel bottles. I put about three - four fuel bottles in my backpack... makes it handy to carry into the woods and my saw takes exactly one fuel bottle every refill. The bottles are spill proof and ther eis no spoilage.

 

[Marco]

Ever notice how many folks are putting premium in their cars at the pump? Would stand to reason that the premium may be the oldest gas at the station.

 

[ciscoguy01]

"Chevron gasoline can be stored for a year without deterioration when the storage conditions are good -- a tightly closed container and moderate temperatures."

Quoted from the link from above......With the key words being tightly closed container. The plastic jugs with the clip caps and such, let all the lighter, higher octane gases, evaporate off the gas, in as little as a few days, in warm weather. The best, more explosive gases, evaporate first.
I store & carry all my gas in sealed metal cans to stop the evaporation.

Your right dude. That's absolutely true. Gotta be a sealed container. Wanna hear something funny? Do a search on Octane. It's chemically impossible to add octane to gas. It's not a liquid. When I see guys spending $5 on a container of 105 octane boost i just laugh. Most don't realize what they are doing is adding something that doesn't give the gas higher octane, it just causes the gas to combust at a higher compression. Kids... Whatcha gonna do eh?

 

[Marc1]

On the topic of old gasoline...I was 20 and had found a way to make money by making bricks.
All was good but I needed a truck badly.
So I found a farmer who had abandoned an old Morris 1954 8 tonner in his vegy patch many years before. Pumpkins had almost completely covered it, the tyres had sunk 1/3 in the dirt, the engine was frozen solid, and the leads insulation had been eaten up by rats.
I took the head off, cleaned the rust out of the cylinders and got it to turn again. I cleaned the carby, petrol pump and glas filter the best I could. Changed points spark plugs and leads, primed the carby with fresh petrol and got it started. I forgot to check the petrol tank that was half full and the thing kept on going on 4 - 5 years old petrol no problems.

 

[Marc1]

..... It's chemically impossible to add octane to gas. It's not a liquid. When I see guys spending $5 on a container of 105 octane boost i just laugh. Most don't realize what they are doing is adding something that doesn't give the gas higher octane, it just causes the gas to combust at a higher compression. Kids...

Octane is not a liquid?...depends what octane are you talking about.

Octane is a mesure of how much compression the fuel can handle before autoignition.

Yet the octane grade of fuel is rated by mixing two components found in petrol, octane and heptane and comparing their knocking level to the fuel to be graded.

So Octane is a liquid, my word! It is an hydrocarbon with eight carbon molecules.

Octane rating can be improoved, of course it can.
Since octane is mesured according to a mixture of octane and heptane, all you need to do is to add more octane and you will obtain higher grade gasoline.
Alternatively you can add other components that produce the same result, resistence to autoignition. The cheapest is Tetraethil lead, however it is banned and only allowed in Aviation fuel. Other additives are alcohol, Toluene and MMT, all very well known octane busters.

However fuel that has higher octane does not automatically translate in more power or better combustion, and so adding octane buster to an egnine that does not need it is a waste of money. Only an engine that suffers from poor performance due to autoignition will have some benefit from it.
However it is true that high octane fuel is also manufactured with higher grade components, so as a fringe benefit, higher octane comes with better quality and so even if a 2 stroke engine 32:1 mix has an octane grade of (say) 65 or 70 octanes ( I don't remember exaclty) and the engine is desinged to take it, the higher quality of fuel in the high octane, will still give some benefit to 2 stroke engines.

 

[bcmktg]

Octane is not a liquid?...depends what octane are you talking about.

Octane is a mesure of how much compression the fuel can handle before autoignition.

Yet the octane grade of fuel is rated by mixing two components found in petrol, octane and heptane and comparing their knocking level to the fuel to be graded.

So Octane is a liquid, my word! It is an hydrocarbon with eight carbon molecules.

Octane rating can be improoved, of course it can.
Since octane is mesured according to a mixture of octane and heptane, all you need to do is to add more octane and you will obtain higher grade gasoline.
Alternatively you can add other components that produce the same result, resistence to autoignition. The cheapest is Tetraethil lead, however it is banned and only allowed in Aviation fuel. Other additives are alcohol, Toluene and MMT, all very well known octane busters.

However fuel that has higher octane does not automatically translate in more power or better combustion, and so adding octane buster to an egnine that does not need it is a waste of money. Only an engine that suffers from poor performance due to autoignition will have some benefit from it.
However it is true that high octane fuel is also manufactured with higher grade components, so as a fringe benefit, higher octane comes with better quality and so even if a 2 stroke engine 32:1 mix has an octane grade of (say) 65 or 70 octanes ( I don't remember exaclty) and the engine is desinged to take it, the higher quality of fuel in the high octane, will still give some benefit to 2 stroke engines.

Marci is definitely correct when he says that octane rating is the measure of how much the fuel/air mixture can be compressed before auto-ignition occurs. A clearer picture of the combustion process in an IC engine might be to think of the event in terms of flame travel. If you consider all the factors which must be in correct balance for combustion to occur at its greatest efficiency, you realize all IC engines are designed with a calculated fuel "octane rating". Some of the more important factors involved in the combustion process are compression ratio, cylinder temperature, ignition timing and spark, fuel/air ratio, cam duration/valve overlap, engine rpm and power range, and of course, fuel octane rating. If you also think of all those things that have to come together so precisely for it to even work at all, much less efficiently, the dynamics are truly exciting and spectacular. Hey, the same spectacular combustion thermodynamics you see every time the space shuttle blasts off into outer space occur in your hotrod Stihl or my old Remington Pl-5 every time the piston fires. It is no less than magic.

Let's say, for the sake of discussion, that you are modifying your engine one factor at a time and you choose to raise the compression first. By raising the compression you have decreased the amount of time it takes for the compressed fuel/air mixture to burn completely and increased the tendency to pre-ignite (detonation). You could change one of the other factors like retard the ignition timing a bit, but that would defeat your purpose. The easiest and most effective thing to do would be to raise the octane level of the fuel to increase the flame travel and yield more power through a longer period of piston travel. Yeah, mo' power! Let's look at two classic examples, each at opposite ends of the IC spectrum from each other:

The diesel engine - extremely high compression, long stroke, lower rpm range, shorter cam duration, low octane fuel, etc. You ever wonder what that noisy, 'knocking" sound is when you hear one running? It is the same type of detonation that will destroy your hotrod Stihl. You see, this engine was designed to run under these conditions. It uses the extremely high compression to compress the air in the combustion chamber to ignition temperature and, at precisely the right instant, the diesel fuel is injected into the superheated air of the combustion chamber and combustion occurs. Voila! No spark plugs or ignition system! I've been thinking of getting a bumper sticker for my 2001 Dodge truck with the Cummins diesel that says "Real trucks don't need spark plugs". Maybe I will.

How about something at the other end of the spectrum? Let's look at a IC aircraft engines. Lightweight, high compression, high power-to-weight ratio, air cooled like your Stihl, fairly high valve overlap and advanced ignition timing, and in addition, many are turbocharged to increase combustion density, especially at high altitudes. Can you see why you would want long, cool burning flame travel with very low tendency towards pre-ignition? If you put 87 octane auto gasoline in one of those, it would run horribly up until the time it holed a piston and locked up. That is why those engines use specially formulated aviation gasoline with an octane rating somewhere between 100 and 120 octane depending on the engine.

In terms of age, I am an old fart at 58. I have no formal engineering education. Everything I know about such things I have learned over the years by tinkering with cars, motocycles, farm tractors, model airplanes, chainsaws, lawn mowers, and you-name-it. While it is not infallible, what I learned along the way has served me well. That also explains why the above description might not be accurate enough for some people. lol

How much do you know about your saw? Here is a simple question to ponder that may lead to a greater understanding of fuel/air ratio: When you turn either of the caburetor mixture adjustment screws, is that screw basically controlling a flow of fuel mix or a flow of air?

Later, dudes.

 

[jack-the-ripper]

The local Stihl dealer told me to use 89 octane in my saws, not 92/93 octane. I have ran premium in my Husky from day one. Also use premium in the mower, snowblower and stringtrimmer without any problems.

 

[ciscoguy01]

Odd

The local Stihl dealer told me to use 89 octane in my saws, not 92/93 octane. I have ran premium in my Husky from day one. Also use premium in the mower, snowblower and stringtrimmer without any problems.

That's odd dude. When I bought the new saw last monday, they told me only to run 93 in the darned thing. Strange from one dealer to the next eh?

 

[computeruser]

Ever notice how many folks are putting premium in their cars at the pump? Would stand to reason that the premium may be the oldest gas at the station.

Depends where you're buyin' gas. In some of the big-dollars neighborhoods where everybody drives cars that call for it, it is actually a hot seller.

 

[RiverRat2]

Marc1 is spot on

On the topic of old gasoline...I was 20 and had found a way to make money by making bricks.
All was good but I needed a truck badly.
So I found a farmer who had abandoned an old Morris 1954 8 tonner in his vegy patch many years before. Pumpkins had almost completely covered it, the tyres had sunk 1/3 in the dirt, the engine was frozen solid, and the leads insulation had been eaten up by rats.
I took the head off, cleaned the rust out of the cylinders and got it to turn again. I cleaned the carby, petrol pump and glas filter the best I could. Changed points spark plugs and leads, primed the carby with fresh petrol and got it started. I forgot to check the petrol tank that was half full and the thing kept on going on 4 - 5 years old petrol no problems.

The key is a sealed system, I have a good friend who is a labtech @ Exxon/Mobil refinery near Beaumont TX, His Job is to test the Octane rating On the Gasoline as it comes off of the distillation towers before it is blended and he acually grades the gas on which it will be according to his results, Ie Regular/Mid grade Or Premium it is then piped to the Tank Farm where it is stored as was stated in the thread, He also monitors the Gas while it is stored and the oldest stuff is what is going out to us the consumers.. Also that octane # you see on the pump is Garunteed minimum rating @ the time it gets to us. The actual octane when we get it is usually two to three points over what is listed on the pump,,,,, If you buy from a station that sells lots of fuel and is always getting a good turn over of their storage... so your 89 or mid grade fuel is actually 91/92 but as also was stated if you dont have a quality fuel can and just cheapo plastic jugs and it is exposed to the suns radiant heat and high temps like in the back of your truck causes it to vaporize all the good stuff that is blended in to keep it at that minimum rated octane level......... you are better off to just mix what you will need and turn it over every couple of weeks or get some of those expensive fuel cells,,, what ever kind of can you have keep em cool and shaded,,, anyway


Just my take on it,,,,,

 

[ol'homey]

What are the physical signs that tell you that you need to run premium in a saw? Can you hear or feel a saw ping under load? It seems like there would be a drastic drop in power under load if a single cyl small engine were pinging right?
I do notice a difference in power, ease of starting etc. when going from old 87 gas to fresh 87 gas. But I've never been able to detect a difference between fresh 87 and fresh 91 gas. Could the reason be my 87 gas was fresh (actual octane higher than 87) and my 91 was not as fresh (actual octane lower than 91) as mentioned previously?
Last question: If an engine without computer control of timing or a knock sensor runs on 87 under load without pinging how is it going to make more power by running premium. IOW does going from "not pinging" to "really not pinging" make more power? Note I understand how a modern auto engine can advantage of the extra octane by advancing the timing to make more power until knock is detected. What I don't understand is how putting premium into an engine with a fixed timing curve that is not pinging on 87 is going to make more HP just by changing to premium?

 

[Marc1]

At age 15 I was in charge of looking after a brand new Bungartz walk behind tractor we had aquired. It had a 250cc Sachs 2 stroke stationary engine that run on 25:1 mix with SAE 30 motor oil.
After a few month of feeding it that crappola of fuel, it would develop a crust of carbon in the chamber and start pinning. All i needed to do was to take the head off, scrape the carbon and put the head back on. It did not even need a gasket. No more pinning...for a few more month.