Weird Visual Fuel Test

[blsnelling]

If it doesn't pour anymore......maybe I can use a spoon!

I bet it'll run

 

[super3]

I hope to do some testing within the next few days to compare cut times with the same saw and chain and chainging only the fuel from 100LL to 93 octane gasoline. I'll report my findings here.

I remember reading a post where someone tested 89,93 and 100+ octane in the same saw and wood with times recorded.
Can't remember who,and iv'e searched and can't find it.
Anyone know who it was?

 

[Carlyle]

Now after all that, I've bought into this thing. Just last week I purged all my saws of gasoline and filled them with AvGas. So I'm guilty too. I'm suspectful that AvGas is causing poor idling characteristics, poorer throttle response, greater chance of carb icing, and less power over all. Why? It doesn't burn as hot. Again, these are just my surmisings. I've yet to prove any of them to myself. I will be testing the power differences here soon though.

Brad,
I agree that the AV gas reacted the same for me. I tried fix'n the idle problem on the 5100 and the 460 and said forget it(even had my EDT-8 tach with me). I don't like screwing with saws in the woods when there are other things to be done. I was leaning the saws sooo much that I wouldn't want to run 91/93 octane and be even leaner. I may try the AV again but 2.5 gals was enough for me at this point. As a side note I did realize that I would have to retune the saws when switching, but the scope of retune is not worth it for me. I will just replace fuel lines and not not leave gas in saws for any period of time. I will bet you that there aren't any measurable power differences and with that said give me 89 or higher.

Carlyle

 

[Lakeside53]

From the link I referenced above..

Grades 100 and 100LL avgas are based on alkylate. As such, it is mainly a
synthetic product – few of the compounds in avgas come directly from crude
oil. Toluene is often added to Grade 100LL to help meet the rich-mixture
antiknock requirement. Grade 80 avgas may contain some straight-run
gasoline distillate that has been subjected to additional purification after
distillation, because of the lower antiknock requirements of this grade. Light
hydrocarbons, such as butane or isopentane, typically are added to all grades
to meet the minimum vapor pressure requirement. Finally, additives are
added: the required concentration of the appropriate tetraethyl lead/ethylene
dibromide/dye mixture plus any of the optional additives the refiner chooses
to use

 

[Orange Hill]

Most modern Stihls have a flap disc that seals pressure in the fuel tank. If there's a vacuum in the tank, air can be drawn in, but nothing gets out. Therefore, I don't see how therecan be evaporations problems in a chainsaw. Perhaps this is why I've never had a problem with them.

I hope to do some testing within the next few days to compare cut times with the same saw and chain and chainging only the fuel from 100LL to 93 octane gasoline. I'll report my findings here.

The plastic used for the fuel tank is microscopically porous and allows the volatiles to dissipate and allowing oxygen in. If you have ever seen a person paint a plastic fuel tank it always bubbles up the paint.

The interesting thing with new E10 fuels is their ability to wick moisture from the air. I am curious if you had measured the fuel samples on a gram scale when they were new if any of the pump fuels would gain weight from water absorption.

 

[demographic]

Motorcycle fuel tanks have a breather, I would be interested to see what happens if those bottled had a small hole in the lid to simulate that.

Regards scott.

 

[oneoldbanjo]

Motorcycle fuel tanks have a breather, I would be interested to see what happens if those bottled had a small hole in the lid to simulate that.

Last week I dumped all the bottles into my lawnmower. They all looked and smelled fine and there was no evidence of anything having gone bad even after a year of sitting still. The oil had not settled out of any of the fuels that were mixed and I did not see any phase seperation visually. I did drill a small hole into the cap to simulate a breather.

I am not sure that the results prove anything - the bottles were stored in my insulated garage and were not subject to any temperature swings or heating cooling cycles that occur in barns or unheated garages. I did notice that the plastic bottles that had the Avgas and Race Fuel had a funky white haze and the bottles were no longer clear after the fuel was dumped out. The motorcycle I have has a plastic tank and the manufacturer warns not to use Avgas or Racing fuel as it will make the tank swell - the plastic absorbs something in those fuels and the tank grows and gets very soft.

I may retry this experiment again with some fuel in the heated garage and some in the pole barn where it gets lots of temperature swings. I do know that if I had this fuel in my motorcycle tank for that same year it would have gone bad.....the bottles just didn't seem to properly simulate real world conditions.