Another chainsaw dyno...

[Catman]

Some language, but sums up my thoughts on printers...

HILARIOUS

 

[davidwyby]

My MS260 with the large carb will run on 92 octane gas but the saw will almost always act like a dog that sneezes on their food and pees on it if they don’t like it.

That gas ends up being fed to my 1968 JD 140 lawn tractor which will run even on stale gas.

So I’ve continued to run 87 gas since for all my saws.

I recently got some vp110 in order to get away from ethanol. I didn't immediately notice a power loss in my MMWS 6100, but I noticed unburnt fuel/oil mess coming out of the muffler. After talking to @Benwa I checked the plug, rich. Had prev been tuned in wood. I also noticed I was filing depth gauges down and pushing harder to keep from 4 stroking. I was kinda distracted from the fuel thing by the chain sharpening to go faster learning thing. So I put some TruFuel premix in it. No re-tuning. Wow, woke it right up and started to clean up the plug. I think Tru is 91. I had read somewhere in the past that someone with a dyno went richer and richer on oil mix, tuning as they went, and made more power down to 18:1. My theory is more oil burning longer makes more power, and the remaining unburnt oil seals rings better.

Which brings me to my two questions - would 87 with lots of oil make more power? the 87 lighting easy (kindling) to get the oil (hardwood) going?

AND - if I retune leaner=hotter with the 110, will it run better?

Thanks!

 

[cuinrearview]

I recently got some vp110 in order to get away from ethanol. I didn't immediately notice a power loss in my MMWS 6100, but I noticed unburnt fuel/oil mess coming out of the muffler. After talking to @Benwa I checked the plug, rich. Had prev been tuned in wood. I also noticed I was filing depth gauges down and pushing harder to keep from 4 stroking. I was kinda distracted from the fuel thing by the chain sharpening to go faster learning thing. So I put some TruFuel premix in it. No re-tuning. Wow, woke it right up and started to clean up the plug. I think Tru is 91. I had read somewhere in the past that someone with a dyno went richer and richer on oil mix, tuning as they went, and made more power down to 18:1. My theory is more oil burning longer makes more power, and the remaining unburnt oil seals rings better.

Which brings me to my two questions - would 87 with lots of oil make more power? the 87 lighting easy (kindling) to get the oil (hardwood) going?

AND - if I retune leaner=hotter with the 110, will it run better?

Thanks!

I would suggest that you not consider the two conditions above as connected. I mean, they are, but changing fuels is just like heading up the mountain to cut. The saw will react differently given different conditions.

 

[srcarr52]

I recently got some vp110 in order to get away from ethanol. I didn't immediately notice a power loss in my MMWS 6100, but I noticed unburnt fuel/oil mess coming out of the muffler. After talking to @Benwa I checked the plug, rich. Had prev been tuned in wood. I also noticed I was filing depth gauges down and pushing harder to keep from 4 stroking. I was kinda distracted from the fuel thing by the chain sharpening to go faster learning thing. So I put some TruFuel premix in it. No re-tuning. Wow, woke it right up and started to clean up the plug. I think Tru is 91. I had read somewhere in the past that someone with a dyno went richer and richer on oil mix, tuning as they went, and made more power down to 18:1. My theory is more oil burning longer makes more power, and the remaining unburnt oil seals rings better.

Which brings me to my two questions - would 87 with lots of oil make more power? the 87 lighting easy (kindling) to get the oil (hardwood) going?

AND - if I retune leaner=hotter with the 110, will it run better?

Thanks!

The lowest octane fuel that you can run without detonation will yield the most power. Higher octane fuels allow you to run higher compression and further advanced ignition timing to produce more power. Oil mixture depends on the oil and type of fuel, methanol takes a lot more oil due to the solvent effect of the alcohol. Mostly the power gained from a richer oil ratio is from less friction, lower operating temperature, and better ring seal.

 

[davidwyby]

So, throw the 110 in the sand rail and or the 429 Ford that need it and keep some fresh 87 around for Csaws. Or 92 to be the same as the Tru? Hmm. It will have a little eth, but I will keep smaller amounts and use it up. I run 40:1 because I can buy non eth premix in that ratio for storage, etc.

 

[Sawrain]

The lowest octane fuel that you can run without detonation will yield the most power.

Why?

Flame/combustion speed does not relate to octane rating.

Of course it might just be true with some pump gas, but that does not make it true overall.

 

[ferris]

Wow ... Over 7.2 Hp from a muff modded 462 ... I knew I liked them saws!!! And porting adds even more!

For me the HP numbers are not most important thing. I bet 1000€ that a dyno at the Stihl / husqvarna factory will show other numbers. So u can only compare the numbers from this dyno.
For me the % of gains from a muff mod or something else are more important.
So I can see what power gains i can expect from a muffler mod on this model.

here are 6-7% gains

 

[srcarr52]

Why?

Flame/combustion speed does not relate to octane rating.

Of course it might just be true with some pump gas, but that does not make it true overall.

They pretty much coincide until you get into oxygenated fuel.

 

[NightRogue]

The lowest octane fuel that you can run without detonation will yield the most power. Higher octane fuels allow you to run higher compression and further advanced ignition timing to produce more power. Oil mixture depends on the oil and type of fuel, methanol takes a lot more oil due to the solvent effect of the alcohol. Mostly the power gained from a richer oil ratio is from less friction, lower operating temperature, and better ring seal.

I will 2nd this
My experience is the same, i will always try to run lowest octane fuel on my saws. Thats how you get the most power out of it. High octane technically "retards" the flame, low octane "advance" flame.

Also i accidentally discovered on 084 with dual flywheel key, with the wrong slot which will advance tremendously can run with high octane gas. Ignition is advanced but the fuel doesn't ignite as soon like low octane, so it fires correctly and will run

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[Bigmac]

There is also less need for high octane with rpm, high engine speeds reduces the time for preignition to occur. 12k+ and it’s not even possible, per Honda’s r+d.

 

[davidwyby]

So...since we can't hear detonation in 2smokes, 91
or 87? Husky n steel say 89...

 

[Bigmac]

So...since we can't hear detonation in 2smokes, 92 or 87? Husky n steel say 89...

You can hear detonation a two-stroke, but you may not hear it in a chainsaw. Working on two-stroke motorcycles and quads I’ve heard pinging in them, but it’s usually closer to torque peak or below at wide-open throttle or heavy loads like climbing a hill, I have also had my share of burn downs, that I heard or felt nothing out of the ordinary. I think the higher working rpm of a chainsaw allows them, to when they go lean just score on the exhaust side, versus going lean in a piped two-stroke, will usually burn the exhaust side of the piston off at the edge of the piston. And sometimes still have plenty of lubrication left for the piston. Sometimes it willeven burn a hole in the center of the piston from too much timing, but oiling wasn’t the issue so there may be no scoring. But the bigger two-stroke motorcycle engines work at a much lower RPM range than chainsaws, so it’s a totally different world.[/QUOTE]

 

[mdavlee]

So...since we can't hear detonation in 2smokes, 92 or 87? Husky n steel say 89...

Always 87 corn free if I can get it.

 

[Nutball]

So...since we can't hear detonation in 2smokes, 92 or 87? Husky n steel say 89...

I've heard it in a stock 2188. It was a subtle sound that I wasn't sure about. It went away with 93 octane, 89 mid grade wasn't enough. The same goes for the Volvo I drive. Under enough load at certain rpm it sizzles, but it takes premium to make it stop, and there's a noticeable power increase and 3-5mpg increase.

 

[NightRogue]

The only time you'll need high octane gas in chainsaw is when compression is too high and ignition is too advanced, now it fires too soon and pings/knocks, misfires, detonate or whatever you want to call it.

You run high octane to stop the fuel from burning before it should, it has the ability to not fire before ignition comes in completely and tolerate heat

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[Nutball]

I think most brands say to use premium or at least 89 octane in stock saws. I only heard the knock/ping in the 2188 around the usual working rpm somewhere below 10,000

 

[NightRogue]

Compression ratio on a chainsaw is among the lowest compared to any other engines, it has about 7:1

Cars generally have compression ratio of 8:1 to 14:1, diesel 14:1 to 23:1 thus the no need of ignition(glow plug doesnt count). Compression ratio aka static compression determines how much the motor can harness from the fuel combusted. Higher ratio= more heat= more power, they need higher octane to burn correctly and cooler

The low ratio for chainsaw makes them gain from ignition advance and compression increase with using low octane gas.

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[RI Chevy]

Just curious why the E-Free canned fuels seem to only offer 93-95 octane? Like VP SEF and Sunoco, etc...

 

[huskihl]

Am I right in thinking that fuel loses it’s octane over time? And faster yet if not sealed as well?

 

[MustangMike]

Two things:

1) I will not disagree that lower octane fuel can result in better performance, but I think Stihl sometimes recommends 91 octane. I run 93 octane because higher octane results in lower operating temps, which should result in longer saw life.

2) Diesel engines are a completely different animal. Diesel fuel is lower octane that gas, they can operate at higher compression because they have direct injection. The direct injection prevents pre ignition.