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Well, I have come to the conclusion that this subject needs to be addressed. I am going to share my knowledge, and ask for others to share theirs!

1) Gasoline - What is it?

We all know gas is an oil / petroleum product, but what it really is, is a mixture of MANY different chemicals. If you were to analyze a gallon of gas from one station, and then analyze a gallon from a different station, they may be COMPLETLY DIFFERNT chemical make-ups! Also, if you wait 10 days, and re do this test, the gas would be different AGAIN!

The important thing about gas, is WHAT it does, and how it behaves.

2) What is this OCTANE thing?

Octane is a rating. It rates how PRONE or UN-PRONE a gasoline is to "Compression Ignition" This is also known as DETONATION..... And is when gasoline/air mixtures SPONTANEOUSLY COMBUST, due to PRESSURE exerted on the mixture. To high of a compression engine, and low octane gas, are sure to detonate, and cause problems inside your motor.

3) So what's in gas?

I don't have the exact facts in front of me, but basically, gas is made up of organic compounds.....All organic compounds have carbon and hydrogen in them....how many molecules of each, and what other molecules are attached, determines what chemical it is. Gas contains a wide variety of these carbon "chains" with various compounds having "names", and others only having chemical "formulas".

There are several "high OCTANE" compounds that are the MAIN ingredient in gas. TOLULENE and XYLENE come to mind. Both with octane ratings in the 115-120 range. When refiners make fuel, they mix enough "GOOD" stuff, with the other compounds, to obtain the correct octane (87 -89- 91-92-93)

3) OK, so what about it's BEHAVIOR?

The Important things about gas are as follows-
(1)- it has to make POWER....this is basically how much HEAT it will produce when you burn a given QUANTITY. This can be rated in BTU's. Lets say a gallon of gas has 100,000 BTU's......all gas, no matter what, needs to have a very similar BTU rating, and it does! Refiners adjust mixtures to obtain this "ideal number"
(2)- It has to evaporate....This is required to get it to BURN, LIQUID does not burn, but vapors do! Again, this is adjusted, and refineries change this depending on the weather! Summer gas will NOT BURN WELL at -40* F! This feature is called volatility, or vapor pressure.
(3)- It has to BURN the same, from day to day- year to year. By this I mean if it takes 3 qubic feet of air to burn 1 ounce of fuel....This behavior needs to remain CONSTANT. This feature is called the (pardon my spelling) STICIOMETRIC RATIO! And for Gas, it is about 14.7 to 1 (14.7:1). This means it take 14.7 parts of air, mixed with 1 part gasoline, to burn cleanly, and properly. Any change in this Number, and you would have to change your fuel delivery system....i.e. JETS!

THOSE three things Are The Basic parameters that gasoline is manufactured by.

4) What about this Ethanol stuff?

Ethanol is a grain alcohol. (VODKA?) It has a much RICHER sticiometric ratio, more like 10:1, so if used in a motor, you would need to "JET UP" considerably, the reason for this, is that Ethanol, like Nitrous, releases Oxygen molecules when it is burnt, so it is called an OXYGENATOR. Ethanol also has a HIGH octane rating (100?)

5) If it is like Nitrous, isn't that GOOD?

NO! We already discussed that you have to "JET-UP" for ethanol, but the other problem is that Ethanol contains less BTU's.........more like 80,000 BTU's per gallon. IT DOESN'T MAKE AS MUCH POWER! Common mixtures of ethanol are E-10 and E-85. E-10 contains approx. 10 % ethanol, E-85 has anywhere for 50% to 85% Ethanol (I have a tester, and have tested the stuff many times!)

E-10 is sold in Minnesota all year round (required by law), and is By far the most COMMON gasoline here. We definitely don't need any ISO-HEET here!!!! E-85 is available for FLEX fuel vehicles.

Some stations sell "clear" "non-oxygenated" gasoline. In Minnesota, these pumps are labeled with a small sticker, indicating such, and the sticker indicates that it is only to be used in boats, snowmobiles, small engines and collector vehicles.

I suggest EVERYONE find out about the gas, and laws about the gas for your state, and your riding areas. My calculations suggest that burning E-10 is like jetting your sled DOWN 1 to 2 sizes when compared to "clear" gas.....I have melted pistons to prove this theory! When talking jetting, you really need to know WHAT FUEL you are associating with a given JETTING. (Example - I started looking into the whole ethanol thing a little bit closer, when I burnt down two years ago. I had ridden 1000's of miles in the UP of Michigan, with no problems, and on the first tank of MINNESOTA GAS, I burnt it up! U.P. gas is "CLEAR" - Minnesota gas is E-10!)

6) So if at all possible, I should run High octane, "clear" gas?

YES!.....and NO.........Definitely run "clear" if you can. If you must burn the Corn mash (ethanol) Remember that your sled will behave like it has 1 to 2 sizes LEANER jets in it! Either change your jets, or JET for E-10, and just live with being a little rich when burning "clear" gas. By the way, all FACTORY INSTALLED JETS are safe for E-10! If you burn "clear" gas, those stock jets are going be 1 to 2 sizes RICH.

As for High octane fuel, Ideally you would burn fuel that had JUST ENOUGH octane to keep you from detonating....Reason being, the higher the octane, the LESS BTU's per gallon (less power) It is not a HUGE difference, but it is there! I would suggest running the highest octane PUMP gas you can buy, in any and ALL two stroke engines, unless it is modified, and requires "race fuel".......near sea-level, "pump-premium" is usually 91-93 octane. BEWARE of 93 octane!!!!!! Most 93 octane pumps I have EVER come across, have a sticker indicating that it is "oxygenated", meaning it will behave like E-10, and cause you to be LEAN!!!

As of right now, I have started a list
Minnesota - MOST GAS IS E-10 and is usually NOT LABLED AS SUCH!!!......."Clear" is available, and is likely LABLED!
U.P. - Most, if not all gas is "CLEAR".
SUNOCO "93" - Contains ETHANOL, treat it as E-10!

If anyone else knows the laws, and availability of gas in your area, please post.....
I have blamed several burn downs on E-10, A little shared knowledge can help prevent more.
 

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In addtion to this Ive got a aquantance who is a chemist at a refinery. He advised me that to his knowledge( at least here in the east) ALL fuels of 92 octane and greater are oxygenated, not just sunoco. They use ethanol to boost the octane rating, his advice to me.. dont use it unless you absolutely have to.
 

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TT670 said:
In addtion to this Ive got a aquantance who is a chemist at a refinery. He advised me that to his knowledge( at least here in the east) ALL fuels of 92 octane and greater are oxygenated, not just sunoco. They use ethanol to boost the octane rating, his advice to me.. dont use it unless you absolutely have to.
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In addition to what has been said, here is one of my student handouts;

GASOLINE OCTANE INFORMATION and CARBON BUILDUP

I have done allot of snowmobile (all brands) overhauls and more often see carbon build up as the #1 killer. To prevent carbon build-up in the motor verify thermostats, jet checks, timing /sync checks etc...but In addition I recommend after the break in period the use of synthetic oil, AND USE LOW OCTANE FUEL. Fact is, lower octane fuel compared to higher-octane fuel has A LOWER FLASH POINT WHICH DRAMTICALLY IMPROVES IDLE AND STARTING. BURNS MORE COMPLETELY AND AT A HOTTER TEMPURATURE, which in turn leaves less CARBON in the combustion chambers and exhaust ports and LESS FOULING OF SPARK PLUGS with un-burned fuel mixture (on a stock motor). Some engine designs require a higher octane or if they are modified to run on higher than 87 octane gasoline. A common misconception even among some of the best engine gurus is: "high octane burns better" It doesn't. High-octane gasoline has a higher flash point, will ignite later, and burn longer (less piston nock) through out the power stoke causing a rough idle on a stock motor. High octane compared to a lower octane in same quantity and air fuel ratio comparison tests PROVE the high octane's intent and purpose does burn longer through the power stroke requiring a more advanced ignition/timing setting for complete combustion. This in turn provides more power through the stroke if only the compression ratio is adequate to support this benefit. If the unit is not intended, tuned or modified for high-octane fuel, DO NOT USE IT.
So with this in mind- here is what you should do to prevent carbon build-up
Fuel conditioner/carbon guard to prevent carbon build up and stabil use all the time to prevent fuel degradation with 87 octane will provide the best protection from carbon build up and provide the best chance for complete combustion on a properly tuned, stock set up that doesn't have a compression ratio over 9.3 to 1. The primary additive in higher-octane fuels is a anti-knock compound which are less combustible than the fuel itself. Also, lower octane fuels do not have ADDITIVES taken out of them. Hope this clears things up.
Jim
ttt
 

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just something i have noticed maybe it will add to this or not, but when i put a higher octane in my truck, higher from 87 to 89, i get better gas mileage and more power pulling my sled trailer. is this a valid point??

Also i don't want to quote anybody but i think it was Big John that said in TT670's, how to optimize a 600 HO thread, that higher octane is your friend, i am assuming the higher the better. Maybe someone else can add to that one.
 

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I did a little research here in Michigan and found out through the Dept of Agriculture (oversees fuel) that our legislature put forth a bill that was signed by Gov. Granholm Jan '04 that removed the stickers on pumps indicating whether or not it contained Ethanol. So in Michigan, we no longer know what the gas has in it!!
Pretty stupid if you ask me. The only way to know is to ask the station owner and hope they know and hope they tell you the truth. Also, as of now, MI is not mandated to use ethanol blends.

Tweener, are all brands jetted safely for ethanol or only those made in the US?
 

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all skidoos since the mid 90's when oxegenated fuels came out.
By the way, say you jet your sled on the fringe and then add "dry gas" you will be too lean.
 

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Fantastic info guys! Thank you.

I too get better fuel milage on my Suburban when towing by using 91 octane gas.
And I guess I just figured that 91/93 octane would always be better in my sleds too.
I will now start paying more attention, after I check and see what the comp. ratio of my 600SDI is, to see for sure if it is over 9.3:1 or not, off hand I don't know.
And I live in Michigan, and if the pumps don't have to have the stickers on them any more, which I did have noticed were gone, I'm not I'll be able to do much about it, will I?
In the past, I have had many times where I was forced to use the 87 octane due to the fact that was all that was available, and I have always been a little leary about going WOT for long runs until I got some higher octane fuel in the tank.
Sounds like I was worried for nothing, and I can now let 'er rip knowing I'll be removing any built up carbon.
I don't have pyrometers on this new sled, but when I was racing 25 years ago I had them on all my sleds. I wonder what the exhaust temp differences would show between hi & lo octane gas?

Anyway, thanks again for all the great info, I learned something today.

Now if I could only learn how to make it snow...
 

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I believe the reason a number of automobiles get better fuel mileage with higher octane fuels.. is due to the knock strategy in that engine.. and that the engine has a knock sensor.. that retards the timing.. if the engine is in a knock condition - 1. poor quality fuel...2. excess carbon in the combustion chamber raising compression or a piece of glowing carbon that preignites the mixture and under heavy loads.... can be as simple as too tall gearing for the conditions.

I whole heartedly agree with this statement when dealing with 2 cycle engines:

"Also i don't want to quote anybody but i think it was Big John that said in TT670's, how to optimize a 600 HO thread, that higher octane is your friend, i am assuming the higher the better. Maybe someone else can add to that one."

But would add the qualifier Good fuel is a two cycles (particularly with raised compression or pipes or restricted stock exhaust - anything that raises the mep (mean effective pressure) in the cylinders ) best friend. But by good fuel, I would like to see the octane raised by adding a good race fuel to the good high volume "clear" premium.... but would rather add that to a hi volume low octane fuel rather then some hi octane fuel that has sat in a dealers tank for a long time. I personally use a 50/50 mix so that if I am forced to add from an unknown station, hopefully I do so with at least a quarter of a tank of fuel left.. and then I usually will not completely top it off. Insuring that the octane level is still high.

Lots of people don't like to use Aviation gas.. due to the vapor pressure issue; but I have never had a problem in a sled.. when not mixing over 50%.

I would agree that when dealing with a 4 cycle engine that the lowest octane fuel which does not knock, will make the most power and you might see 1 or 2 hundreths of a second improvements in ET. I make this last statement having won a few national NHRA events with low compression stockers and made 1000's of time trials..

And if you are not out to beat your best buddy who runs within a ski length of you normally and just out riding to have fun; jet a little on the rich side for safety sake...

A couple of articles on gas and detonation which are worth reading.. compliments of Hammer from Snowest.

The meaning of Gas

VP Racing Fuels

Detonation

Detonation and timing
 

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Discussion Starter · #12 ·
Good follow ups.......

Trucks and casoften run beter from High octane cause they have a knock sensor, and the TIMING is advanced untill it KNOCKS, then it bacs it off just a little, to keep it from knocking.......The higher octane ALLOWS more advance! Only SDI'sand Powertechs offfer this same "timing alteration" for the rest of us......no such luck.

Sleds have DIFFERNT comp. rations then cars, and there are WAY TO MANY variables in sleds, toallow a conp ratio to octae needed chart!!!!

Run whatever is recomended for your sled, I always run PUMP PREMIUM, cause it gives you a little "cushion" when jetting closeto the edge.......higgh octane fuel burns slower, and cooler, so it can save you from a melt down if you are jetted a little lean!!!

DO NOT put 100 octane in your stock sled........it will be slower.
 

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tweener said:
Good follow ups.......

Trucks and casoften run beter from High octane cause they have a knock sensor, and the TIMING is advanced untill it KNOCKS, then it bacs it off just a little, to keep it from knocking.......The higher octane ALLOWS more advance! Only SDI'sand Powertechs offfer this same "timing alteration" for the rest of us......no such luck.

Sleds have DIFFERNT comp. rations then cars, and there are WAY TO MANY variables in sleds, toallow a conp ratio to octae needed chart!!!!

Run whatever is recomended for your sled, I always run PUMP PREMIUM, cause it gives you a little "cushion" when jetting closeto the edge.......higgh octane fuel burns slower, and cooler, so it can save you from a melt down if you are jetted a little lean!!!

DO NOT put 100 octane in your stock sled........it will be slower.
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People run stock sleds???? I keep swearing to cut a hole in the hood to put oil in and to padlock it shut.. but have not been able to do it....
 

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Discussion Starter · #14 ·
I am UNAWARE of any CONSUMER version snowmobile, that will not run JUST FINE on E-10........

manufactrers jet slds for Worst Case Scenario... E-10 is getting t be VERY COMMON, and they are jetting the sleds to run on E-10

The older arctic cat EFI's had a little "shunt" in the wiring harness to change the EFI program for E-10 or "clear" gas......Problem was that the tings were programed SO RICH, that you could easily run the sled with it set up fo "clear"........fill your tank with E-10.........and It woul be JUST FINE, and actually run a little bit better (they gave you really rich jetting)
 

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So far we hae learned that

---- MI has removed the labels from the pumps.
---- Most PUMP gas 92 octane or HIGHER is E-10
---- Illinois is mostly E-10
---- MN is mostly E-10....NON E-10 is LABLED

I also have to agree with the 92 or higher is E-10......I have talked to severalrefinery workers, and they have told me that only3 grades of gas are pumped through the pipelines ha crisscross the united states....87, 89, and 91.........

92 is nothing more than 90% 89 octane, and 10% ethanol
93 octane is 90% 91 octane and 10% ethanol

(I did some rough calculations)
 

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Discussion Starter · #17 ·
UP-DATE.........

Minnesota wants to increase ethanol precentage in gasoline from 10% to 15%!!!!

For those of us living or riding in Minnesota.........call your state legislators and representatives, and tell them YOU DO NOT WANT them to increase the Ethanol content of gasoline!

Ethanol is more expensive than gasoline.......the state supsedises the cost.........so our tax money will go towards this!

Ethanol has less BTU's per gallon.......meaning fuel millage will go down.

Ethanol is hard on rubber and other components in your engine.....more breakdowns, and expensive fuel pumps, injectors, etc.

And most importantly.......

Ethanol SUCKS in your 2- stroke motors.
 

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tweener said:
UP-DATE.........

Minnesota wants to increase ethanol precentage in gasoline from 10% to 15%!!!!

For those of us living or riding in Minnesota.........call your state legislators and representatives, and tell them YOU DO NOT WANT them to increase the Ethanol content of gasoline!

Ethanol is more expensive than gasoline.......the state supsedises the cost.........so our tax money will go towards this!

Ethanol has less BTU's per gallon.......meaning fuel millage will go down.

Ethanol is hard on rubber and other components in your engine.....more breakdowns, and expensive fuel pumps, injectors, etc.

And most importantly.......

Ethanol SUCKS in your 2- stroke motors.
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I agree with your comments but unfortunatly our world is changing and the reality of the US finding alternative fuels that are non foriegn dependent are coming too close around the corner. Ethanol plants are going to start coming up around the country and e-85 may be common real soon. I think it sucks. The 2-stroke motors I feel have its days numbered, I bet in 5-10 years we will talking about grinding valves and changing cams in our sleds.
 

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If the average age of snowmobilers is 45 - in 5-10 years we'll be talking about who has the best buffet line and which golf clubs work best.
 

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Irondog said:
If the average age of snowmobilers is 45 - in 5-10 years we'll be talking about who has the best buffet line and which golf clubs work best.

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Good one that! I liked this post and all like it. Just being a shmo who just has a 500SS, I just fill it up with 87/Regular everywhere I go and have no problems. For the dirtbike, I mix the 2-stroke oil of choice along with "Super/Premium-unleaded-91, 92 or 93 octane, whatever the gas station has, and am done with it, I pour it into my Honda CR 500R and go ride, no problems in all these years. The Mercury V6-150hp outboard, since new, has been getting the cheapest TCW-II/III oil that money has been able to buy since I've had it along with the 89 octane which Mercury recommends and the motor just plain runs. The Honda CBR 1000 tells me to use 87 and for the 29,000 miles I've run it for, it runs.

It could very well be that for the tuners/Hi-Po guys who want/need more power and like to fiddle and "set-up" for conditions and such, what is in the gas and the octane number make a difference, however, as I and no one else has any control whatsoever over what the manufacturers are putting into the gas, I'm going to go to the gas station and just shove whatever they have into my tank and just hope for the best. I don't know if there is anything for the "Joe-on-his-snowmolile" regular-guy to worry about, or is there? Am I going to have to start changing my jets? Writing a letter to my legislator? What else can we do, right?
 
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