What octane is best, and why

[~WBF]

It's called 100 Low Lead, but its anything but. It contains more lead than leaded auto gas ever had.
Lead wont kill you, but it will degrade your cognitive ability. Even in small amounts.

it's killed lots of people. I actually thought it killed the Chemist that put lead in Petrol. He did get lead poisoning but recovered
He was killed by another invention of his.
Kidney failure is generally the cause.of death.

 

[Bull Mountains]

it's killed lots of people. I actually thought it killed the Chemist that put lead in Petrol. He did get lead poisoning but recovered
He was killed by another invention of his.
Kidney failure is generally the cause.of death.

Charles Kettering discovered the effectiveness of TEL as a octane booster and he went on to live a normal life.
It's actually pretty rare to die from lead exposure, but it causes all sorts of other issues.
I use 100LL in my big bore stroker Banshee I run on the street, but I am not exposed to exhaust like you are with OPE.

 

[Bull Mountains]

Yup. View attachment 289782

View attachment 289783

The spark plug color is indicative of burning leaded fuel and is normal.
The exhaust drooling could be multiple things from a rich mixture to fuel related.
Which specific VP where you using.

 

[kanscruzer]

You can use a 10mm socket on that right?

If not a bigger hammer is needed

 

[davidwyby]

The spark plug color is indicative of burning leaded fuel and is normal.
The exhaust drooling could be multiple things from a rich mixture to fuel related.
Which specific VP where you using.

110

the pic doesn’t show it well, and that might have been early in the testing/cutting, but I was more concerned about crusty buildup on the plug.

 

[davidwyby]

I tried leaning the carb a bit on the 395 and it didn’t seem to help.

took the VP and put it in my VW buggy for summer storage.

 

[~WBF]

Charles Kettering discovered the effectiveness of TEL as a octane booster and he went on to live a normal life.
It's actually pretty rare to die from lead exposure, but it causes all sorts of other issues.
I use 100LL in my big bore stroker Banshee I run on the street, but I am not exposed to exhaust like you are with OPE.

I was talking about Thomas Midgley jr. He was on Kettering's team. It was his brain baby to use tet lead to stop the knocking even know they new it was harmful to people and environment
In there prototype factories at GM and Dupont they had a few deaths and people going crazy and hallucinating and depression.

Nice stuff.

He got polio and got tangled up in the apparatus he invented to lift himself out of bed and strangled himself.
That's some karma for ya.
Couldn't have happened to a more hated guy.

 

[Bull Mountains]

I tried leaning the carb a bit on the 395 and it didn’t seem to help.

took the VP and put it in my VW buggy for summer storage.

I suspect not as it was lean all ready from not combusting the un vaporized fuel.

 

[Sawrain]

I made it. I skimmed a lot.

I missed the reason for the creation of this thread.

I thought we already settled this the other day when I tried to use VP110 to avoid eth and it slobbered out the muff of the 6100 and lowered power. I gave it a second chance milling in the 395...coked up the plug, didn’t want to hot/warm restart. Back to 87. I think canned runs the best. Might try 90-whatever from the pump next time.

It is safe to say you found a fuel that does not work for your application, but you cannot equate that directly to it being an octane rating problem, there is allot more to a fuel than that once point, it's kind of like the old four stroke back pressure myth, bigger exhausts lost power and missing back pressure got the blame, when it was the reduced velocity or tuning rpm that caused most of the loss.

Below are different types of fuels, their possible octane ratings and boiling points, as you can see, it is choose your octane and take your pick of how to get there, many options exist.

Nope not abit

And despite what you believe, flame travel is the problem, anti-knock compounds are the cure. If it’s moving fast inside an environment that wasn’t built to handle it, what to do? You must slow it down. Yea, cost you some pony's but you live to run another day. That’s all racing fuel talk and I’m familiar. I used torco in blown vettes. Didn’t need it in the winter, only for summer time. I don’t buy the article in whole to say the least, it certainly represents that fellows opinion and I can see you agree. That’s ok.

As I mentioned, knock being caused by simply too fast of a primary rapid heat release is a discredited theory, one that academics of the 60s sparred over.

Having said that, the chemical reactions that underpin knock are still studied to this day, anti knock additives such as TEL (lead) do not act buy slowing primary combustion, they rather magically have little effect until the factors for knock exist, once conditions for knock start, when end gasses begin to break down to form highly reactive radicals, then the TEL joins to these free radicals, mopping them up/stabilizing them, knock problem solved, I assume (yes) they then burn at the correct time when the primary flame front reaches them.

Current methods for increasing octane are more just diluting the fuel with another higher octane substance, which could increase or decrease burn rate.

Below some more fuel vs burning velocity, unfortunately there are some discrepancies with other studies, but these are not from inside an operating internal combustion engine, the point being that there is not a strong correlation between octane rating and burning velocity, iso-octane (AKI 100) and toluene (AKI 114) one of the easiest to get high octane fuels are fairly close,

I’m gonna venture to postulate that the cooling effect of a fuel probably has more to do with power output in a chainsaw than its ability to burn a microsecond faster or slower.

Seems likely.

 

[Bull Mountains]

It is safe to say you found a fuel that does not work for your application, but you cannot equate that directly to it being an octane rating problem, there is allot more to a fuel than that once point, it's kind of like the old four stroke back pressure myth, bigger exhausts lost power and missing back pressure got the blame, when it was the reduced velocity or tuning rpm that caused most of the loss.

Below are different types of fuels, their possible octane ratings and boiling points, as you can see, it is choose your octane and take your pick of how to get there, many options exist.

View attachment 289862




As I mentioned, knock being caused by simply too fast of a primary rapid heat release is a discredited theory, one that academics of the 60s sparred over.

Having said that, the chemical reactions that underpin knock are still studied to this day, anti knock additives such as TEL (lead) do not act buy slowing primary combustion, they rather magically have little effect until the factors for knock exist, once conditions for knock start, when end gasses begin to break down to form highly reactive radicals, then the TEL joins to these free radicals, mopping them up/stabilizing them, knock problem solved, I assume (yes) they then burn at the correct time when the primary flame front reaches them.

Current methods for increasing octane are more just diluting the fuel with another higher octane substance, which could increase or decrease burn rate.

Below some more fuel vs burning velocity, unfortunately there are some discrepancies with other studies, but these are not from inside an operating internal combustion engine, the point being that there is not a strong correlation between octane rating and burning velocity, iso-octane (AKI 100) and toluene (AKI 114) one of the easiest to get high octane fuels are fairly close,

View attachment 289885



Seems likely.

Listen to this guy! He knows of what he speaks.

 

[Bull Mountains]

One other thing to consider. Race gas with octane ratings over 108 are almost never suitable for a two stroke. The reason is their distillation curves are taylored to long intake runner V-8 engines. When you run these fuels in a two stroke a good portion of them pass through the engine without vaporizing and without combusting. This causes the motor to loose HP and throttle response.

 

[davidwyby]

So what would you fuel experts expect or recommend to work best in a saw? The saw guys say lowest octane you can get. But canned seems to run well and it’s 92, IIRC.

 

[Sawrain]

I have never used a canned fuel.

I myself normally use a reputable low priced/octane fuel in most of my saws, ethanol free, I would be more concerned with the quality and manufacturer most of the time over if it is 87 or 89, but depending on where you are in the world it might all be delivered from the same ship anyway.

I have also used high octane pump fuel leftover from my 2t bikes without issue.

I am not denying people have had problems with high octane fuels, really all I am saying is that the often stated it’s because it burns slower is an easy out, that isn’t based on current thinking, that it has to be looked at on a fuel by fuel basis.

 

[Bull Mountains]

I use non ethanol premium from a busy station.

 

[Sawrain]

So what would you fuel experts expect or recommend to work best in a saw? The saw guys say lowest octane you can get. But canned seems to run well and it’s 92, IIRC.

I’ll answer again, if you have the interest level to facilitate it, you could try different fuels at different outlets, I would say there is a good chance the best fuel will come from a certain plant/distributor and for a chain saw this will possibly have as much or more bearing on performance than octane rating, due to the companies culture of production, additives, etc etc.

@Bull Mountains might be able to speak to how much different producers have different ideas on how it’s done?

I have been involved with storage and transport of crudes, not the production end.

 

[Bull Mountains]

So, to dumb this down, you can have, say a 100 octane fuel that performs as well as an 87 octane fuel in a saw if the burn speed is correct for the way a 2 cycle engine uses fuel. Is that the gist? Like I said, I run the vp94 and Sunoco 95 small engine fuels. Ive also ran SEF 90 octane canned fuel and 90 E-free pump from the busy local Sunoco. I have not noticed a difference in Power with any. Often the tune in damn near identical if the weather is the same. Different Oils and their ratios have effected throttle response and output noticably for me, fuels have not if using the same oil and ratio. All that said I've also never put race gas in a saw nor do I feel the need to.

I'd just forget burn speed altogether as it's just not relevant. Instead fixate on distillation curve.

 

[Bull Mountains]

@Bull Mountains might be able to speak to how much different producers have different ideas on how it’s done?
[/QUOTE]
That would be real tough to comment on because each refinery within a company is different. For instance Exxon-Mobil typicaly produces a pretty good product, but the local E-M refinery is a dumpster fire.
Then there is the fact that just because you buy it at one Brands station it doesnt mean that company refined the product being sold and much of the time they actually dont.

 

[Kiwioilboiler]

Then there is the fact that just because you buy it at one Brands station it doesnt mean that company refined the product being sold and much of the time they actually dont.

Especially true in NZ. Ours/mine is the only refinery and supplies 4 brands with 75 odd percent of the entire countries requirements.
The only difference is Techron or Ultimate or whatever name 'additive' is dosed.

"Xxxx is better" (insert brand here) is such a laughable statement.

 

[Busa2r]

If you find your saw likes AVGAS it probably the most consistent fuel there is. As a caveat it does not go bad when sitting, Your piston wash will have a yellow green color and motors start easy regardless of outside temp.

 

[PissRev]

Any of you guys remember the old Amoco white gas? That's what I used to burn in all my two strokes until Amoco was bought out by BP. As a kid, there was a clear window in the gas pump and you could see that the gas was as clear as water.