Hey Saw Troll and other chain saw experts

[jomoco]

Can you give us the lowdown on the important relationship between high compression saws and fuel octane levels? What about the dangers of alcohol levels in today's gas and what can be done to avoid damage using it in our fuel mix.

Does Husky's lower compression ratios make it a better choice over Stihl's higher compression ratio to avoid potential damage with these new fangled fuels?

Pointing out the facts on these important questions would be a great help to all of us at this sight, both beginner and pro.

jomoco

 

[stihlatit]

I can hear Mr. Ben Walker heading this way.

 

[ShoerFast]

Is it excepted that Huskys are lower CR then Stihl?

Alcohol dose in effect lean out pure gasoline, but a catch 22 that works for us here, is that alcohol burns cooler and a little more smoothly then gas, lowering the combustion temp, at the cost of less power.

 

[blis]

just use premium gas with all saws... and about alcohol in gas, in theory it affects the gas properties a bit, but a normal user wont notice any difference as long as the alcohol levels are low...

 

[B_Turner]

And with that any information anyone has about the level of alcohol that dirreretn brands of gas in their area have? Lakeside said he could still get no alcohol gas in his area for example, and I thought all the major gases has some.

A local mechanic told me to stick with Chevron and Texaco for saws, but that might be just what he's been told by someone else.....

 

[SawTroll]

I am waiting for Ben on this one - I have read that alcohol is not good for prolonged use in 2-cycles, but I don't really know.....

 

[ShoerFast]

Alcohol is real easy to test for in gas, as it would rather attach it's self to water, putting for a say, say 100 parts of gas (suspected alcohol mix) in a calibrated beaker, add a measured portion of water, another for a say, say 10 parts of water. Shake and walha, the water and alcohol separates to the bottom, you put 10 parts on water in, but if you end up with 15 parts of water/alcohol in the bottom of the beaker, the gas had a 5% alcohol content.

Not a lab test, but more of a track-trick to get better a starting point for a tune using pump-gas.

 

[B_Turner]

Along these same lines, I had a respected local mechanic tell me once when I told him my 066 sometimes leaks gas from the fuel cap especially when warm tell me that locally certain brands of gas (I believe based on the alcohol content) were better than others in terms of swelling the gasket and not leaking. Another thing I always wondered if it were true.

 

[Lakeside53]

I'd rather not run alcohol in my saws, but one day we all will be doing it... If you use gas containing alcohol (NOT E85!!! - different ball game), you need to retune your carb to run richer... All Stihl's shipped since Jan 1st this year have been tuned for 10% alcohol fuels.


Husky's have a lower compression ratio? First I've heard of it in the USA... Be careful though - In some Eastern European countries and parts of Africa (low quality gas), many Stihl saws are low compression... They just use a 1mm cylinder base gasket instead of a 0.5mm..

 

[blis]

.....
Husky's have a lower compression ratio? First I've heard of it in the USA... Be careful though - In some Eastern European countries and parts of Africa (low quality gas), many Stihl saws are low compression... They just use a 1mm cylinder base gasket instead of a 0.5mm....

thats what ive been wondering too, must be those stihl fans who´ve been spreading lies about good ol'huskies...

 

[bwalker]

Avoid alchol doped fuel if you can. It has many issue which have been discussed in depth here many times. Do a search.
Alcohol based fuels do lean out your mix.

 

[blis]

Avoid alchol doped fuel if you can. It has many issue which have been discussed in depth here many times. Do a search.
Alcohol based fuels do lean out your mix.

but alcohol based fuels withstand higher compression...

 

[treehead]

I work in the marine industry and ethanol has been a mojor thorn in our sides this year, the biggest problem we've had is that it eats fuel lines, fiberglass tanks, and it cleans eveythingcouldn't tell you how many carbs I rebuilt about 3 weeks into the season, best advice to give is condition fuel, and don't let it sit long(loses octane after 2 weeks or so)

 

[Mr.]

Try to mix methanol with the oil you currently use. Good luck.

It takes twice as much alcohol as gas. I would call that REAL lean if you don't allow for more fuel.

Fred

 

[bwalker]

but alcohol based fuels withstand higher compression...

No, they do not. 93 octane straight gase and 93 octane gas with 10% ethanol both have the same octane number.
What can and does happen especially with the marine engines is once there is .5% water in the fuel the ethanol drops out of solution and sits in the bottom of the tank. As the tank runs down you get a big slug of ethanol and water with no oil. To add insult to injury the fuel are mix going tinot the cylinder in this situation is ultra lean to boot. This can and does result in scuffed cylinders. It is very common in outboards ran on ethanol doped fuels.

It takes twice as much alcohol as gas. I would call that REAL lean if you don't allow for more fuel.

Will a stock saw carb even have a enough adjustment and pump enough fuel to run on alky?

 

[SawTroll]

Ben, how about the E85 mentioned by Lakeside?

They are treathening to introduce it here not too far into the future.

 

[CaseyForrest]

Can you give us the lowdown on the important relationship between high compression saws and fuel octane levels? What about the dangers of alcohol levels in today's gas and what can be done to avoid damage using it in our fuel mix.

Does Husky's lower compression ratios make it a better choice over Stihl's higher compression ratio to avoid potential damage with these new fangled fuels?

Pointing out the facts on these important questions would be a great help to all of us at this sight, both beginner and pro.

jomoco

Gasoline has a tendency to "spontaneously combust" in the same way diesel does if the compression and temperature are right. Thats what the knocking is in the engine.

Raising the octane in the fuel effectively raises the point at which the fuel will combust.

 

[Lakeside53]

Ben, how about the E85 mentioned by Lakeside?

They are treathening to introduce it here not too far into the future.

Stihl tells us that there is no 2 cycle oil they have tested that is successful with E85, and absolutely not to run it... The boat guys that filled up with E85 by mistake have already found out the hard way...

 

[jomoco]

Racing Fuel?

After going over the many posts in this thread, the consensus seems to be avoiding alcohol.

However alcohol's inclusion in today's fuel seems to be unavoidable. Which leads me to conclude that the only viable " though expensive " way to ensure I don't damage my saws may be to copy what pro racers do and buy high octane racing fuel.

Does anyone see any downsides to this alternative aside from the added cost?

I've been reading up on high compression ratios on WW11 aircraft motors that were forced to drop their compression ratios in order to supercharge their engines, but once 100+ octane fuels became available they were able to raise them back up again.

It seems to be an accepted fact that higher compression ratios equal higher power output.

Are there any potential downsides to running high octane racing fuel, surely some of you hot saw folks have tried this at some point?

Thanks for the valuable feed back so far.

jomoco

 

[blis]

the biggest downside in running racing fuel in saw is the costs, and its totally overkill to run +100 octane gas on saw...