I just saw a remark in the ms200t mods about fuel being old at the gas station, which reminded me of another good debate. Which brand/octane to use in saws. I usually use 93, but I've gotten flak from some and agreement from others. I was looking through Madsens site and they seem to like the idea of using premium as well. Any thoughts? /forum/images/graemlins/smile.gif
Octane
- Thread starter Leif
- Start date
- Location
- Grand Marais, MN
Also along with that discussion I forgot to recall, the Stihl rep had a very convincing point regarding how old the fuel is once most stations get it - and the breakdown from additives I'm familiar with. He did say that 92 is perfect and the Stihl 2-cycle had stabilizers, so get the high test and mix it right away if you end-up not using it soon.
I never noticed any difference either way, but will now. The new 200t's are retailing over $500.00 and there's no way I'll climb with anything less a saw.
I never noticed any difference either way, but will now. The new 200t's are retailing over $500.00 and there's no way I'll climb with anything less a saw.
- Location
- Western Norway
For the past ten years we´ve been using Stihl mix without benzen, much better for our health. If it´s good for the saw, well havn´t experienced any saws breaking down yet so I guess it is all right.
Svein
www.hogstogrydding.no
Svein
www.hogstogrydding.no
- Location
- Grand Marais, MN
The '05 prices are higher. Uh huh.
- Location
- Canon City ,CO
I generally use Premium in summer and Midgrade in winter. Octane is high enough in the midgrade but premium seems to resist vapor lock better.
Stump
There is no difference in rvp (reed vapor pressure) from one grade to the next. There is a difference between winter and summer rvp.
Around here or the Northeast rvp will be 15psi in the winter and 8 psi in the summer. Around mid April the rvp will start to lower until you hit the 8 psi for the summer gasoline blends. Vapor pressure is usually controlled by Butane blending in the gasoline mainly because it is cheap other light components can be used and are used when butane inventories are low.
Keep a can of gas from the winter, sealed tight in cool place and try to run it in the summer and let me know how you make out.
/forum/images/graemlins/icon314.gif
There is no difference in rvp (reed vapor pressure) from one grade to the next. There is a difference between winter and summer rvp.
Around here or the Northeast rvp will be 15psi in the winter and 8 psi in the summer. Around mid April the rvp will start to lower until you hit the 8 psi for the summer gasoline blends. Vapor pressure is usually controlled by Butane blending in the gasoline mainly because it is cheap other light components can be used and are used when butane inventories are low.
Keep a can of gas from the winter, sealed tight in cool place and try to run it in the summer and let me know how you make out.
/forum/images/graemlins/icon314.gif
dats funny /forum/images/graemlins/elefant.gif
- Location
- Canon City ,CO
Jersey, I'm not disputing you but what is the explanation for the vapor-lock "cure" in Premium? Is it because the higher octane fuel runs cooler in the saw or because the premium sells slowly and half of what is in the station's tank Aug. 1 is still winter formula? Why wouldn't the winter stuff be MORE volatile than summer and more prone to vaporlock in summmer temps.-in cold temps you need the fuel tovaporise easier, right?
stump
I guess I should have started by saying the EPA sets standards for vapor pressure.
The reason for this is VOC emissions, by lowering the vapor pressure you also reduce the amount of voc emissions. The rules apply to the Northeast, and may not apply in your area.
You are right in that when the temp is colder out you will need a higher vapor pressure. When its hot outside you can lower the vapor pressure because the temp is helping to vaporize the fuel.
Why would one grade vapor lock and not the next?
When gasoline is blended different base stocks are used. Octane cost more at the pump but it also cost more to produce. Gas with a 87 octane will be the cheapest base stocks, generally coming from non-conversion units. Will the change in the base stock cause vapor lock, I would think not because the vapor pressure is the same in the end product. I think I already said that vapor pressure is controlled when the gasoline is blended but this is to hit the final target. When the base stocks are produced there are many control points to meet. This are a range and not a fixed number so you could be on the top of the range with one tank and at the bottom with another.
With this all said the question still has not been answered. Maybe the blend was not even in the correct range, lab error maybe, tester sent in the wrong tank sample?
/forum/images/graemlins/crazy.gif
I guess I should have started by saying the EPA sets standards for vapor pressure.
The reason for this is VOC emissions, by lowering the vapor pressure you also reduce the amount of voc emissions. The rules apply to the Northeast, and may not apply in your area.
You are right in that when the temp is colder out you will need a higher vapor pressure. When its hot outside you can lower the vapor pressure because the temp is helping to vaporize the fuel.
Why would one grade vapor lock and not the next?
When gasoline is blended different base stocks are used. Octane cost more at the pump but it also cost more to produce. Gas with a 87 octane will be the cheapest base stocks, generally coming from non-conversion units. Will the change in the base stock cause vapor lock, I would think not because the vapor pressure is the same in the end product. I think I already said that vapor pressure is controlled when the gasoline is blended but this is to hit the final target. When the base stocks are produced there are many control points to meet. This are a range and not a fixed number so you could be on the top of the range with one tank and at the bottom with another.
With this all said the question still has not been answered. Maybe the blend was not even in the correct range, lab error maybe, tester sent in the wrong tank sample?
/forum/images/graemlins/crazy.gif
I wasn't joking, whats reed vapor pressure? Is reed supposed to be Reed, someones name, maybe the guy that devised the scale to measure this pressure? I live in FL, I wonder if they bother with this summer/winter fuel here, it does hit 20* here occasionally. /forum/images/graemlins/confused.gif
I got this from another site, I hope it helps.
OK I've been working in the oil refinery for almost 30 years. The unit I work on is a Cat Cracker, its main product is unleaded gasoline. This is straight from the book.The measure of volatility is vapor pressure. Vapor pressure is measure of surface pressure it takes to keep a liquid from vaporizing. (Reid Vapor Pressure is the correct name, named after the man who invented the test appartatus RVP)A light hydrocarbon like propane has a very high vapor pressure, oil has a very low vapor pressure. With that said lets look at engines. You need on cold starts about 10% of the gas to vaporize to get it started, if you have to much RVP you will have vaopr locks when starting a hot engine. RVP in the winter in Minnesota will run as high as 13 PSI, in the summer in Texas RVP will be 8.5 PSI. Octane is a term to discribe the molcule C8H16 which is Iso-octane and it has an octane number of 100 and is a standard for testing the octane number of gas.This is done in a knock engine You can changethe compression ratio of the engine by raiseing and lowering the head. This engine has a Knock-O-Meter to determine when an engine starts knocking while it is running. They raise and lower the head to make it knock. Octane numbers are Research Octane Number (RON) and Motor Octane Number(MON). The RON number is a test that simulates driving under mild driving conditions. The MON number is a test of preformance under the full range of conditions. In the late 60's the Federal Trade Commission came up with RON+MON over 2 rating you see on pumps today. The design of the engine demands that the fuel behave a certain way. Compression ratio of an engine determines the amount of power it can deliver. The higher the compression ratio, the longer the power stroke, the more powerful the engine. Basicly our old engine have low compression ratios and should use a lower octane gas. Could go into more detail, but it gets kind of long. I hope this helps explain what you wanted to know.
BUD BORDELON
OK I've been working in the oil refinery for almost 30 years. The unit I work on is a Cat Cracker, its main product is unleaded gasoline. This is straight from the book.The measure of volatility is vapor pressure. Vapor pressure is measure of surface pressure it takes to keep a liquid from vaporizing. (Reid Vapor Pressure is the correct name, named after the man who invented the test appartatus RVP)A light hydrocarbon like propane has a very high vapor pressure, oil has a very low vapor pressure. With that said lets look at engines. You need on cold starts about 10% of the gas to vaporize to get it started, if you have to much RVP you will have vaopr locks when starting a hot engine. RVP in the winter in Minnesota will run as high as 13 PSI, in the summer in Texas RVP will be 8.5 PSI. Octane is a term to discribe the molcule C8H16 which is Iso-octane and it has an octane number of 100 and is a standard for testing the octane number of gas.This is done in a knock engine You can changethe compression ratio of the engine by raiseing and lowering the head. This engine has a Knock-O-Meter to determine when an engine starts knocking while it is running. They raise and lower the head to make it knock. Octane numbers are Research Octane Number (RON) and Motor Octane Number(MON). The RON number is a test that simulates driving under mild driving conditions. The MON number is a test of preformance under the full range of conditions. In the late 60's the Federal Trade Commission came up with RON+MON over 2 rating you see on pumps today. The design of the engine demands that the fuel behave a certain way. Compression ratio of an engine determines the amount of power it can deliver. The higher the compression ratio, the longer the power stroke, the more powerful the engine. Basicly our old engine have low compression ratios and should use a lower octane gas. Could go into more detail, but it gets kind of long. I hope this helps explain what you wanted to know.
BUD BORDELON
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