What's the best fuel for chainsaws?

[pleasant]

Briggs and honda single cylinder 4 strokes are typically around 80psi compression, 2-strokes are knackered if they only have 80psi.

[openspaceman]

14 minutes ago, pleasant said:

Briggs and honda single cylinder 4 strokes are typically around 80psi compression, 2-strokes are knackered if they only have 80psi.

That is "cold" pressure, the pressure at combustion is considerably higher as the flame front moves through the charge before the piston has got far down its power stroke. Pinking and knocking are forms of detonation of the fuel-air in front of the flame front caused by engine heat and the pressure of the combustion before the flame front reaches there.

 

Essentially the combustion fuel-air pressure is the  true compression ratio (measured after the exhaust ports have closed) plus the pressure from the heat of combustion, if it was no more than the pressure achieved from pulling the engine over it wouldn't run at all.

 

So risk of detonation increases with engine temperature and is one reason water cooled engines can run with higher compression ratios than air cooled.

 

I don't know of any liquid cooled chainsaws either.

[doobin]

2 hours ago, pleasant said:

Absolutely correct, but not all esso stations sell it in that format so be careful, but essentially a large percentage do. So, yes you can get esso premium which is ethanol free and thats the stuff to go for

From Esso:

 

"Although our pumps have E5 labels on them, our Synergy Supreme⁺ 99 is actually ethanol free (except, due to technical supply reasons, in Devon, Cornwall, North Wales, North England and Scotland). Legislation requires us to place these E5 labels on pumps that dispense unleaded petrol with ‘up to 5% ethanol’, including those that contain no ethanol, which is why we display them on our Synergy Supreme⁺ 99 pumps."

 

Is this accurate?

[pleasant]

2 minutes ago, doobin said:

From Esso:

 

"Although our pumps have E5 labels on them, our Synergy Supreme⁺ 99 is actually ethanol free (except, due to technical supply reasons, in Devon, Cornwall, North Wales, North England and Scotland). Legislation requires us to place these E5 labels on pumps that dispense unleaded petrol with ‘up to 5% ethanol’, including those that contain no ethanol, which is why we display them on our Synergy Supreme⁺ 99 pumps."

 

Is this accurate?

Like I said, not all esso stations, are selling enthanol free e5. As per that press release

[pleasant]

7 minutes ago, openspaceman said:

That is "cold" pressure, the pressure at combustion is considerably higher as the flame front moves through the charge before the piston has got far down its power stroke. Pinking and knocking are forms of detonation of the fuel-air in front of the flame front caused by engine heat and the pressure of the combustion before the flame front reaches there.

 

Essentially the combustion fuel-air pressure is the  true compression ratio (measured after the exhaust ports have closed) plus the pressure from the heat of combustion, if it was no more than the pressure achieved from pulling the engine over it wouldn't run at all.

 

So risk of detonation increases with engine temperature and is one reason water cooled engines can run with higher compression ratios than air cooled.

 

I don't know of any liquid cooled chainsaws either.

Yes, i was obviously referring to cold compression readings.....i didnt realise in your post i was responding to, that you weren"t

[openspaceman]

2 minutes ago, pleasant said:

Yes, i was obviously referring to cold compression readings.....i didnt realise in your post i was responding to, that you weren"t

I should probably have said combustion pressure but even that can be open to a bit of question.

 

 

[pleasant]

24 minutes ago, openspaceman said:

I should probably have said combustion pressure but even that can be open to a bit of question.

 

 

Yup.. Very true. And fair enough.

[Dan Maynard]

4 hours ago, aspenarb said:

I was always led to believe that you should not use high octane fuel in a two stroke, I use the cheap gear at the pumps, batch mix about 40ltrs at a time twice a week. Cant say I have ever seen a problem with water in the fuel.

 

Bob

If you're buying once a week you won't, and modern saws are designed to be fine on E10. There have been tales on here of people's 088 seizing, as it is brought out rarely and hence has fuel that's sat in it.

 

[Dan Maynard]

16 hours ago, Mark_Skyland said:

Everyone should give it a try, dump your fuel into a clear container, I bet most people will find that it looks cloudy. Leave it for an hour or so and then check it out. Look for a water bubble at the bottom. 

I'll be interested to try this, I work on the theory of only storing saws with full tanks because then there's no air for them to absorb water from - but will be good to know if it works.

 

Same is supposed to be true for water in diesel tanks which leads to diesel bug, iirc.

[Mr. Squirrel]

18 hours ago, trigger_andy said:

Yeh, from what Ive read on here you can run you engine on Unleaded indefinitely but switching to Aspen will suddenly causes the issues you mention above. So don’t switch abd you’re good to keep running on Unleaded. Want to make the switch? Then it will kill

your saw, but it’s the petrols fault, not Aspens. 🤣

So if you really want to get bent over the barrel and run Aspen then first change out everything you suggest and get bent over twice. 
 

It’s a no from me. 

I mean that’s slightly dramatic. It won’t kill your saw, it’ll just need some maintenance…

I started running my all my saws on aspen about 4 years ago, had some teething issues with my 10 year old 200, but it was probably past time for a bit of maintenance anyway. Think it was less than £100 to have it running good as new again. The others, everything from 150t though to my 661, have been absolutely fine. 
Saws I’ve bought since and started on aspen obviously don’t have any issues. 
To me aspen is a no brainer, better for your saws, less harmful to your health 👌🏻