Ethanol Free gas
- Thread starter larrypac
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Premo in 2 strokes is mandatory for pre-ignition, leading up to detonation and more pre-ign. when running air cooled engines Balls Out.
Ethanol up to 15% is ok except for air moisture. It actually raises octane.(another story for that)
Miscibility of ethanol in water is infinite. (it is in solution) Just check the half full old vodka bottle.
Nearly same as for water in ethanol.
Air moisture is not just water in solution. Air has contaminates, and so does the water in the air.
Gasoline with eth. has limited solubility
So gasohol mix will separate what is not in solution.
This brings chemicals from the gasoline out(sulfur, calcium, mag, man) out of the gasoline as a precipitate.
White/yellow chalks found in carb.
cliff
Premium isn't mandatory in two stroke chainsaws. They have very low compression ratios.
The other thing is higher octane doesn't prevent pre ignition. It prevents detonation.
No pissing match here, but deto leads to hot chamber leads to pre-ign.
Pre-ign. leads to deto also.
True, higher octane ******* deto. but, it also slows burn rate and heat rejection to chamber and spark plug, near TDC.
Typicaly no. Because the portion of the chamber where deto occurs is on the exhaust side at the outer edge where it's hottest. The center near the spark plug tends to run much cooler.
Pre ignition is usually caused by plug heat range, mettalic deposits, to much timing advance, or a combination of the those three factors.
Higher octane does not slow burn rate either. Slowing burn rate lowers octane as the faster you can burn the fuel air mixture the less chance you have for detonation to occur. The fastest burning gasolines are pro stock drag fuels, which also have some of the highest octane ratings.
No pissing match, just stating the facts.
Now, deto can lead to pre ignition if you have one or more of the three factors I mentioned above, butbit typicaly doesnt. Once pre ignition haopens you end up with a hole in the center of your piston almost instantly.
I have seen many pistons that failed from deto and several from pre ignition, but known have shown evidence of both phenomenon going on.
All true, except we are mainly speaking of 2 stroke engines.
No hot exhaust valves to deal with!
c
The only time I've had any serious damage that I blamed on ethanol was in the carb of a little Yamaha inverter generator. It was clogged with stuff just like that. Because I've been careless about leaving ethanol fuel in all kinds of engines, and this is the only real damage I've experienced (not counting poor running from stale fuel as damage), I put it down to a materials compatibility issue. I'm more careful since seeing that goo.
There was nothing I said that pertains to four strokes exclusively.
Interesting.. Is there a difference between "burn rate" and "propagation of the flame front"?
According to Google..
The propagation of a flame front is influenced by a number of factors, including the fuel's octane rating, the mixture of combustible species, and the environmental conditions:
- Octane rating
Fuels with a higher octane rating burn more slowly and are better balanced against spontaneous combustion. This means they resist knocking and detonation, which can damage a car engine.
That's poor information on Googles behalf. In fact it's dead wrong.
The amount of terrible information on the web regarding this particular subject is astonishing.
Google up Kevin Cameron if you really want to understand it. He is a tech writer for Cycle world and a Chem engineer IIRC.
4gr/usg for Sunoco 260 TEL
5gr for 280 TEL
Base fuel was crap back then so fuels had TEL added.
Mexico had 85 R+M/2 octane with lead! in the '80's
Burn and propagation are 2 different things.
0-5% MFB is considerably different in hi v. lo octanes.
5-95% is similar.
"Burn" as thought of is how easily to start self propagating flame.
"Propagation" is rate of heat release.
High octane fuels are slow to "burn" or get self sustaining.
It plays catch-up and ends ending after exhaust opens.
Very detrimental to output, unless hi-comp. or a leading spark advance is used.
cliff
This is fun!
Happy Thanksgiving to all!
0-5% MFB is considerably different in hi v. lo octanes.
5-95% is similar.
"Burn" as thought of is how easily to start self propagating flame.
"Propagation" is rate of heat release.
High octane fuels are slow to "burn" or get self sustaining.
It plays catch-up and ends ending after exhaust opens.
Very detrimental to output, unless hi-comp. or a leading spark advance is used.
cliff
This is fun!
Happy Thanksgiving to all!
No, they are not...
What you're describing is the low end of the distillation curve or the 10% boiling point. This has nothing to do with octane or flame speed, which was what you were originally talking about.
A good example is winter blend fuel ignites easier than summer blend fuel, yet they have the same octane number.
Octane is just a measure of flame stability. Detonation is what happens when the fuel being combusted becomes unstable during combustion and explodes instead burns smoothly.
My head hurts.
No and No and close.
Mass Fraction Burned-Not distillation curve.
Winter fuel is bit better on octane due to benzene
Octane is resistance to knock by definition, nothing else.
All of that is false... and this is coming from a guy that works in oil refining. I routinely review quality parameters of gasoline as a function of my job.
The benzene content of gasoline is very low and does not increase in the winter. Winter fuel is higher in volatility so it ignites easier. The fuels octane number is blended to the same numbers regardless of season. Benzene is a lower volatility stream so increasing it would be counter productive. Blending to higher octane numbers than required is also counter productive to the refineries bottom line.
And Octane is a measure of a fuels resistance to detonation. Knock is a symptom and not an abnormal combustion phenomenon in and if itself.
Hermio
Addicted to ArboristSite
I will add to that info by defining detonation, which few understand, and which is often a mis-used term. Detonation is the propagation of a chemical reaction within a medium at the speed of sound within that medium. Essentially, it is triggered by a shock wave or a highly compressed front which travels through the medium. In the case of a fuel-air mixture, the compression wave raises the temperature to the auto-ignition temperature, thus ignition occurs as the compression wave travels through the medium. In the case of true explosives such as dynamite or TNT, the shock wave alone is enough to trigger the decomposition of the explosive. By contrast, gunpowder does not detonate; it just burns quickly. If it detonated, it would destroy the gun barrel.
Thanks for reminding me to update Puregas for the ONLY place that sells 87 E0 in the area - or I'd say region. There are a bunch of forest / remote folk who bite the bit to only get E0 premium at its premium price. If you don't need the octane its a complete waste. Unfortunately the fuel depot is out of the normal way.
I run E0 regular in the generator (used daily in the winter), the log splitter and ATV. I tried a tankful in the pickup and , yes, I monitored the results. I gained fuel mileage but it was a break even for E10 when all was said and done at a $0.30 increase for regular E0. I won't get into the political side but if the fuel stop was closer I'd use nothing but their stuff.
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