91 octane OK?

[513yj]

I use premium in all of my small engines from the lawnmower to my pro and homeowner chainsaws. I like higher octane especially for 2 stroke motors since there is oil in the fuel.

 

[Mike Gott]

I run e free 87 octane because all I can get here. What about adding octane booster, how would that work, both my saws are ported too

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[Mike Gott]

What about 100 octane low lead air plane gas?

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[sb47]

I race Motorcycles, so I have plenty of race fuel. I run U4,4 in my race bike and it's originated 105 octane. I also run it in my saws.
2 strokes do like a higher octane. Using 105 it revs quicker and doesn't bog at full throttle as much. Been running it in all my saws for years, no issues.
Race gas smells great too! lol

 

[hardpan]

Not sure about your state but in Tennessee, that is a violation of weights and measures regulations. You should report it to your State Weights and Measures department. That gas should be pulled off the market.

I agree with you. Locally we have terrible high levels of ethanol at some stations. The weights and measures people here only care about accurate weight scales and volume of pumps or liquid containers. They don't check the contents though personally I think 10% should be measured at 10%.

 

[Whitespider]

That's very interesting. I think this helps explain why some guys here report no issues with e10...

Like I always say... It ain't that they've been lucky, it just that they ain't been unlucky yet.
It ain't hype, and it ain't paranoia; I've given more funerals, 5-to-1, for small engines and/or their carburetors using gasohol than those that don't... and carb overhaul kits 10-to-1. I just did another one this weekend... dad's blower from Minnesota lake home where ethanol blended is all he can get locally.

Before using an octane booster I'd do some serious and comprehensive research... most are just snake oil, and can add problems of their own.
Using leaded gasoline, even "low-lead" aviation fuel, can also create problems in a small engine not designed for it... if the tune ain't properly maintained lead deposits can form, which can result in pre-ignition, or worse, detonation, which can be instantaneously catastrophic to a small engine.
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[Mike Gott]

Those are my options, regular 87 octane or or low lead 100 octane aviation gas, so what's my best choice. Everything else is 10% ethanol

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[sb47]

First of all lets educate those that are miss informed about octane ratings and what they are use for. The octane rating is designed to give you an idea of how flammable the fuel is.
There is a myth that the higher the octane is, the more flammable it is. (Wrong) In fact, it's just the opposite.
Low compression motors with 11:0 to 1 or less, can run on low octane gas.
High compression motors that run over 11:0 to 1 or higher need a higher octane fuel to combat pre-ignition.
Higher compression motors need a fuel that resists pre-ignition by being less flammable.
Diesel motors are very high compression motors, upwards of 16:5 to 1 or higher.

There are gas companies that don't do quality control and they buy and sell low grade fuel to save money and reduce operating cost. Some have been found to ad waste oil and other nasty things to fuel to stretch there inventory.
Sometimes it's not that E10 is bad fuel, it's where its kept and what else is in it.

Racing fuel comes in all flavors and all octanes. Some are unleaded and some leaded. Some are oxygenated and some are not. They come in a range of octane levels from 87 to 187 or even higher.
You can go to VP or Sunoco and view all there race fuels.

I think VP even offers a fuel designed for chain saws but I'm not sure.

I use VP U 4.4 witch is a 105 octane leaded oxygenated fuel in my race bike because I run 13:5 to 1 compression.
I also use VP C 110 when I cant get the U44.
Both run fine in all my saws.

I don't run race fuel because of the octane rating alone. It is also oxygenated, so there is oxygen infused in the fuel.
More oxygen in, means you get a better burn of the fuel.

"One must use caution though! running the wrong fuel or running a fuel without the rite air fuel mixture, can and will over heat your motor"

Sometimes ethanol gets a bad rap because other things have contaminated the fuel and they blame it on the ethanol.

You can get race fuel at most Motorcycle dealers boat dealers and race shops.



Sunoco
http://www.racegas.com/

VP
http://www.vpracingfuels.com/

 

[sb47]

Also when you add an octane booster you can only boost the octane a few numbers. Adding more octane booster does nothing after a certain point.
Adding transmission fluid to fuel is like adding an octane booster.
What you are doing is raising the flash point so the fuel will resist pre-ignition.
The flash point is the amount of heat it takes for the fuel to ignite.
The lower the octane the lower the heat needed to ignite it.

 

[Sawyer Rob]

Those are my options, regular 87 octane or or low lead 100 octane aviation gas, so what's my best choice. Everything else is 10% ethanol

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Actually, you have one other option, you can go to your saw dealer and buy pre-mixed fuel from them.

SR

 

[sb47]

 

[Mike Gott]

I understand what you are saying, I'm just wondering if a low lead higher octane gas would be better than a low octane regular gas.

 

[Marshy]

Also when you add an octane booster you can only boost the octane a few numbers. Adding more octane booster does nothing after a certain point.
Adding transmission fluid to fuel is like adding an octane booster.
What you are doing is raising the flash point so the fuel will resist pre-ignition.
The flash point is the amount of heat it takes for the fuel to ignite.
The lower the octane the lower the heat needed to ignite it.

You are confusing autoignition temperature and flash point... Autoignition temperature is the temperature where a fuel source will ignite without a ignition source. Flash point is the temperatuer at which the fuel vapor will ignite in the presense of an ignition source like a spark plug. Knock and ping describe the same condition where the fuel is properly ignited by its ignition source but the flame front propagates incorrectly and pockets of fuel explode causing an irregular pressure wave inside the combustion zone, hence a ping/knock noise. A high octane fuel will resolve ping/knock issues but not autoignition issues. For autoignition issues you need to run a cooler engine or cooler spark plug.

 

[Whitespider]

Those are my options, regular 87 octane or or low lead 100 octane aviation gas, so what's my best choice. Everything else is 10% ethanol.

Well... sort of a hassle... but...
If you mix two parts 87 octane with one part 100 low-lead you end up with approximately 91 octane and dilute the lead content by 2/3's (likely to a non-consequential amount).
Also, I believe aviation fuel is not a reformulated gasoline (i.e., no oxygenates added)... meaning your resulting mix would be slightly higher in energy content than straight pump gas and should be less susceptible to short-term spoilage (i.e., should have a bit longer shelf life).
Not to mention you'd save a couple bucks.

A 50/50 mix would give you an approximate 93 octane and a somewhat higher lead content... but cost a little more with likely no realized benefit.
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[sb47]

You are confusing autoignition temperature and flash point... Autoignition temperature is the temperature where a fuel source will ignite without a ignition source. Flash point is the temperatuer at which the fuel vapor will ignite in the presense of an ignition source like a spark plug. Knock and ping describe the same condition where the fuel is properly ignited by its ignition source but the flame front propagates incorrectly and pockets of fuel explode causing an irregular pressure wave inside the combustion zone, hence a ping/knock noise. A high octane fuel will resolve ping/knock issues but not autoignition issues. For autoignition issues you need to run a cooler engine or cooler spark plug.

The pinging is caused by pre ignition. Pre ignition can be caused by several things. One being the timing being set wrong. The other is the fuel is being ignited before the piston reaches top dead center.
By the time the air fuel mixture reaches the combustion chamber the fuel is mostly atomized and in a vapor form.

Auto ignition is the result of compression. When you compress an air fuel mixture to a certen point, the pressure alone creates heat and makes the air fuel mixture ignite. This is very similar to pre ignition.

High octane fuels help by being harder to ignite from high pressures in the combustion chamber.

Also carbon build up on the valves and in the combustion chamber can stay hot and cause per ignition.

When the fuel ignites before top dead center, you have the force of the mass of the motor wanting to move forward. But if the fuel ignites before top dead center, it wants to force the motor backwards.
But the centrifugal force of the turning mass will force the motor forward. This is where the pinging is coming from.

 

[sb47]

I understand what you are saying, I'm just wondering if a low lead higher octane gas would be better than a low octane regular gas.

You probably wont see much difference in the 2 fuels you are asking about. Most motors can run a average range in octane with no issues or difference in performance. Most two strokes do use a higher compression then most 4 strokes. Therefore a higher octane would work a little better in them.

I do believe that race fuels are a better quality fuel over plane ol pump gas.

I believe aviation fuel is also formulated to be stable at low temperatures when you fly at high altitude. I also believe aviation fuel is a much better quality.

The difference is with race fuel you can get what you are looking for. Leaded or unleaded, oxygenated or non oxygenated, and in a verity of octane ratings.

 

[sb47]

2 stroke motors generally run a higher compression because when you add an oil mix to the fuel, you are raising the octane ratio.

With a fuel that is oxygenated you can force a little more fuel into the air fuel mixture and still get a complete burn before it is forced out the exhaust port.

Burn rate is key as well. Not all fuels burn at the same rate.

To make fire you need three things, oxygen, fuel and heat. But the ratio needs to be in a range where it can burn properly.

 

[Whitespider]

2 stroke motors generally run a higher compression because when you add an oil mix to the fuel, you are raising the octane ratio.

That is incorrect...
Oil... near any oil... near all oil... including diesel fuel... has a much lower octane rating than gasoline (but diesel fuel has a higher cetane number).
Mixing two-cycle oil with gasoline lowers the octane rating (slightly)... it does not raise it.
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[sunfish]

91 non-eth is what I run, but would rather have 89. Most of my saws are modded too.

 

[sb47]

That is incorrect...
Oil... near any oil... near all oil... including diesel fuel... has a much lower octane rating than gasoline (but diesel fuel has a higher cetane number).
Mixing two-cycle oil with gasoline lowers the octane rating (slightly)... it does not raise it.
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I see your still at it! lol Your a piece of work!