Another chainsaw dyno...

[d997tt]

Did he advance the timing when going from 87-91/92? No.
You don’t just add higher octane, you have to tune for it to take advantage of its higher potential (in this case advanced timing)
Of course it can be argued that “well, I don’t always have access to higher octane so I tune for 87”. Ok, fine, but that does not disprove the potential.

 

[d997tt]

If you haven't done it on saws then from my perspective it's still theoretical...

Never dynoed my saws, no, but all my saws run 100ll and 40:1 Motul 2t. All are faster than with 87 or 93, even the Husky AT and Stihl C

 

[RI Chevy]

How do you know your saws are faster? You time cuts? Or seat of the pants feel?

 

[d997tt]

How do you know your saws are faster? You time cuts? Or seat of the pants feel?

Both, before and after actual timed tests and you can lean into them a bit more

 

[d997tt]

I, for one, am willing to chip in $ to Joe to do the octane testing on the dyno. Takes the wood and operator out of the equation. Id like to see 87 E-free vs the rest including VP 94 and Sunoco Optima 95. Both are small engine fuels.

Is he going to also change timing and afr after switching to higher octane? If there is no change in the tune when switching to a higher octane then the test is incomplete and irrelevant, benefits will not be realized and the claim can be made “it’s no better, just cost more”

 

[RI Chevy]

OK.
Your the next guy up.
Do some testing for the good of the order. Take your mtronic and adjust the timing to your octane.
Do some video'd test cuts before and after.
School us here...

 

[d997tt]

OK.
Your the next guy up.
Do some testing for the good of the order. Take your mtronic and adjust the timing to your octane.
Do some video'd test cuts before and after.
School us here...

Haha! Being a new member I can’t school anyone.
Don’t you know how that works? History + lot of people are set in their ways. And that’s fine, I just report my findings. No problem if it’s accepted or not

 

[RI Chevy]

Maybe we can all learn something. Bust the old theories out. We need some new technology theories in here.

 

[d997tt]

Maybe we can all learn something. Bust the old theories out. We need some new technology theories in here.

The Stihl ms500i is on it’s way to newer car-level tech, but it’s still a low pressure system so it’s limited.
There are many ways to make a combustion engine perform better. The more completely you address what it needs the more power you will make. Fuel/oil/spark/compression/afr/flow are all factors. If any of those are overlooked then you will have lower limits.

 

[Egg Shooter]

Is he going to also change timing and afr after switching to higher octane? If there is no change in the tune when switching to a higher octane then the test is incomplete and irrelevant, benefits will not be realized and the claim can be made “it’s no better, just cost more”

He's probably to busy to do all that but I can't speak for him. It would be time consuming. Using the computer saws can only go so far I assume. I'm not even sure if they have the ability to change the timing themselves. I've not owned nore used an M-tronic / Autotune saw yet.

 

[Egg Shooter]

Maybe we can all learn something. Bust the old theories out. We need some new technology theories in here.

This only works for the open minded. That's in short supply up in here.

 

[Red97]

All with a Muffler mod

661,390xp,500i

 

[d997tt]

He's probably to busy to do all that but I can't speak for him. It would be time consuming. Using the computer saws can only go so far I assume. I'm not e even sure if they have the ability to change the timing themselves. I've not owned nore used an M-tronic / Autotune saw yet.

Yes of course it would be time consuming and the owners probably have them tuned with a certain fuel/oil mix they use regularly and wouldn’t want that changed just for the dyno run.
I was stating the possibility of taking full advantage of higher octane. Spark plug choice and gap size is another factor that allows different afr and octane to be used to their full potential

 

[wcorey]

Never dynoed my saws, no, but all my saws run 100ll and 40:1 Motul 2t. All are faster than with 87 or 93, even the Husky AT and Stihl C

Welcome to the forum btw.
Sorry to come off as confrontational but have seen this sort of thing over and over on the forums where someone pops in and thinks their extensive experience with other-than-saws is going to disprove some commonly held principal of saw tuning/porting.
Might happen someday but so far zip...
We have many regulars here with a combined huge depth of performance tuning knowledge with about any type of power plant you can think of and I have to say it's rare that much of it ends up changing the way we do saws in a significant way.

All I can say is that I haven't had the same experience with octane vs performance, and for what it's worth I have dyno'ed a few saws.
I have a small airport up the road where I also get 100ll but use it mainly for it's stability in storage and hesitate to use it regularly due to the lead.
That and I don't like having the retune everything back and forth for pump gas and then the avgas.
What I'd like to try is a relatively new unleaded avgas, 93UL, but it's not available in very many locations, closest to me is almost a 3 hour round trip.

Seems to me the 661 in the tests should be to some extent advancing itself for max power...

 

[d997tt]

Welcome to the forum btw.
Sorry to come off as confrontational but have seen this sort of thing over and over on the forums where someone pops in and thinks their extensive experience with other-than-saws is going to disprove some commonly held principal of saw tuning/porting.
Might happen someday but so far zip...
We have many regulars here with a combined huge depth of performance tuning knowledge with about any type of power plant you can think of and I have to say it's rare that much of it ends up changing the way we do saws in a significant way.

All I can say is that I haven't had the same experience with octane vs performance, and for what it's worth I have dyno'ed a few saws.
I have a small airport up the road where I also get 100ll but use it mainly for it's stability in storage and hesitate to use it regularly due to the lead.
That and I don't like having the retune everything back and forth for pump gas and then the avgas.
What I'd like to try is a relatively new unleaded avgas, 93UL, but it's not available in very many locations, closest to me is almost a 3 hour round trip.

Seems to me the 661 in the tests should be to some extent advancing itself for max power...

It’s not feasible for some to make changes for various reasons. For others, it’s easy.

 

[Egg Shooter]

View attachment 289162

All with a Muffler mod

661,390xp,500i

Thank you for doing all this Joe. I'll make it down there one of these days.

 

[wcorey]

You don’t just add higher octane, you have to tune for it to take advantage of its higher potential (in this case advanced timing)

In your experience what are the symptoms/signs a saw exhibits with too much timing advance for the octane used?

All I ever get is some exhaust popping and a bit of decrease in power and using a higher octane doesn't seem to change that...

 

[d997tt]

In your experience what are the symptoms/signs a saw exhibits with too much timing advance for the octane used?

All I ever get is some exhaust popping and a bit of decrease in power and using a higher octane doesn't seem to change that...

You partially answered your own question. You’re not burning most of the fuel as you should (besides the crankcase obviously, 2stroke)
It depends on how extreme though. Most people will have the sense to adjust for it obviously if it’s really bad.
If it’s not too bad you can try 1 of 2 things, make your spark plug gap smaller, and/or use a colder plug. (Only downside with colder plug is rough at startup and until it warms up, and it likes a bit more fuel)
Bosch plugs lower number is colder.
NGK plugs higher number is colder.

 

[wcorey]

You partially answered your own question.

And you still didn't answer it, was a simple question...

 

[d997tt]

And you still didn't answer it, was a simple question...

Signs/symptoms: popping, it’s not burning most of the fuel as it should.
likely solution posted also.
Read it again perhaps?