So what's the current Two stroke oil favorite for

[TonyCH]

My buddy would always run 110 octane race fuel thinking he was making more power. We proved it on the dyno that in fact the opposite was true.

Octane is not the thing making more power. Higher octane = more power is a common misconception, like with your buddy.

Octane is one of the factors which determines how much you can advance your timing (and increase compression) without getting pre detonation. And advancing timing and adding more compression are things that allow you to make more power. So, octane and power are related but not the way most people think.

Purely just by using higher octane fuel in an engine with a carburetor does not increase power. But, in fuel injected engine it might, depending on the software ecu is running.

I run 100 octane (US rating) alkylate gas with mix of synthetic oil. It does not make any more power in my chainsaws than other gasolines. But it has other positive effects on both the saw and myself (clean burn, doesn't go bad etc.).

 

[Smitty Smithsonite]

I've come to the conclusion that this stuff is too complicated for my damaged brain to comprehend.

I think it was an instructor at MMI that planted that seed, that higher octane burns "slower" than lower octane fuel does. I still don't doubt this, but I can't prove it. I've heard it from more than one source over the decades. I do realize the ability to ignite has nothing to do with burn speed, but I believe they're interconnected by physics. All this is WAY above my pay grade, lol.

 

[bwalker]

Octane is not the thing making more power. Higher octane = more power is a common misconception, like with your buddy.

Octane is one of the factors which determines how much you can advance your timing (and increase compression) without getting pre detonation. And advancing timing and adding more compression are things that allow you to make more power. So, octane and power are related but not the way most people think.

Purely just by using higher octane fuel in an engine with a carburetor does not increase power. But, in fuel injected engine it might, depending on the software ecu is running.

Correct. Except that detonation and pre ignition are two different things. Pre detonation isn't a thing.

 

[bwalker]

I've come to the conclusion that this stuff is too complicated for my damaged brain to comprehend.

I think it was an instructor at MMI that planted that seed, that higher octane burns "slower" than lower octane fuel does. I still don't doubt this, but I can't prove it. I've heard it from more than one source over the decades. I do realize the ability to ignite has nothing to do with burn speed, but I believe they're interconnected by physics. All this is WAY above my pay grade, lol.

Most people, including those that should have no clue on the subject.

 

[Smitty Smithsonite]

Octane is not the thing making more power. Higher octane = more power is a common misconception, like with your buddy.

Octane is one of the factors which determines how much you can advance your timing (and increase compression) without getting pre detonation. And advancing timing and adding more compression are things that allow you to make more power. So, octane and power are related but not the way most people think.

Purely just by using higher octane fuel in an engine with a carburetor does not increase power. But, in fuel injected engine it might, depending on the software ecu is running.

Yep, known that for decades. But, lots of people still don't - this is true.

 

[bwalker]

I've come to the conclusion that this stuff is too complicated for my damaged brain to comprehend.

I think it was an instructor at MMI that planted that seed, that higher octane burns "slower" than lower octane fuel does. I still don't doubt this, but I can't prove it. I've heard it from more than one source over the decades. I do realize the ability to ignite has nothing to do with burn speed, but I believe they're interconnected by physics. All this is WAY above my pay grade, lol.

Crap repeated over and over is still crap. Make no mistake there is no appreciable difference between low octane and premium as it pertains to flame speed.

 

[TonyCH]

Correct. Except that detonation and pre ignition are two different things. Pre detonation isn't a thing.

Sorry, english is my 3rd language. Well, what is it called then? I was thinking of premature detonation, like the knocking my cars knock sensor tries to prevent.

EDIT: I guess you said it there: pre ignition.

 

[Smitty Smithsonite]

Sorry, english is my 3rd language. Well, what is it called then? I was thinking of premature detonation, like the knocking my cars knock sensor tries to prevent.

EDIT: I guess you said it there: pre ignition.

My '07 Silverado 1500 still knocks and pings at full throttle and heavy loads, unless I run 93. The knock sensor is only able to do so much, I figure.

It's either detonation or preignition - there's no such thing as pre detonation. Detonation is spontaneous combustion from excessive pressure or heat, while preignition is another ignition source besides the spark plug, such as hot glowing carbon, or a head gasket protruding into the combustion chamber.

 

[TonyCH]

Well, maybe. Who am I to argue with native english speakers.

In any case I meant knocking.

 

[bwalker]

My '07 Silverado 1500 still knocks and pings at full throttle and heavy loads, unless I run 93. The knock sensor is only able to do so much, I figure.

It's either detonation or preignition - there's no such thing as pre detonation. Detonation is spontaneous combustion from excessive pressure or heat, while preignition is another ignition source besides the spark plug, such as hot glowing carbon, or a head gasket protruding into the combustion chamber.

Actually detonation isn't spontaneous combustion. Basic sequence is a plug fires, combustion event begins with a gradual pressure rise, as the flame front burns toward the edges of the chamber the unburnt charge starts forming active radicals and suddenly the remaining unburnt charge explodes with a violent rise in pressure.

 

[bwalker]

Well, maybe. Who am I to argue with native english speakers.

In any case I meant knocking.

Don't kid yourself. Your English is pretty good.
Knocking is most often used to describe pre ignition. Detonation often can't be felt or if it can it feels like a small misfire or loss of power.
I had an engine equipped with EGT gages and a data logger. It entered into a detonation event so severe it melted the piston past the second ring and painted the entire exhaust with molten aluminum. The data logger never picked it up. The engine was running great until it wasnt!

 

[North by Northwest]

Most of my expiereance has been with Duraforce motors. I've had three of them and two snowblower with the same basic engine in piston port format.
I'll post some piston pics tonight.

Yeah Duraforce were a later model , some had poor performance due to plastic carburetor flange warpage issues . Bad idle issues aside they were a stout performer when tuned properly & maintained .

 

[Joisey]

Saber or any low ash oil works poorly in a lawnboy motor. And I say this based on expiereance.

https://parkerhomestore.com/?produc...-duraforce-engine-oil-w-stabilizer-8-oz-89930
I'm confused.

 

[calamari]

I just saw an episode on "Engine Masters" where they used a built LS engine with 10:1 compression and tested the power differences that result from 87, 91, California gasoline ( can have up to 10% ethanol), 100, 116 octane leaded race gas and E-85. They ran it as close as they could get it to the same conditions for each run on the dyno on a cold and humid day in SoCal. They used the dyno power reading to set the advance basd upon power dropping off when the advance exceeds optimum. The engine did numerous pulls and the result was that there was no significant difference between the gasoline octanes but E-85 did make a little more power in an engine that made right at 500 hp consistently. The engine, no matter what fuel was used, liked the exact same spark advance. It was felt that E-85 made a little more power because it has a higher oxygen content because of it being 85% ethanol. The reason for the different octanes seemed to be that real world driving involves different ambient temps, various humidities and load durations. A straight pull from 2,000 rpm to redline that lasts a few seconds is different than pulling a load on a grade for many minutes or even hours.
Check the show out. It refutes a lot of conventional wisdom about octanes and its effect.

 

[North by Northwest]

I just saw an episode on "Engine Masters" where they used a built LS engine with 10:1 compression and tested the power differences that result from 87, 91, California gasoline ( can have up to 10% ethanol), 100, 116 octane leaded race gas and E-85. They ran it as close as they could get it to the same conditions for each run on the dyno on a cold and humid day in SoCal. They used the dyno power reading to set the advance basd upon power dropping off when the advance exceeds optimum. The engine did numerous pulls and the result was that there was no significant difference between the gasoline octanes but E-85 did make a little more power in an engine that made right at 500 hp consistently. The engine, no matter what fuel was used, liked the exact same spark advance. It was felt that E-85 made a little more power because it has a higher oxygen content because of it being 85% ethanol. The reason for the different octanes seemed to be that real world driving involves different ambient temps, various humidities and load durations. A straight pull from 2,000 rpm to redline that lasts a few seconds is different than pulling a load on a grade for many minutes or even hours.
Check the show out. It refutes a lot of conventional wisdom about octanes and its effect.

Interesting info . I'll check it out . I realize alcohol was utilized to increase the octane rating , however rather surprised E-85 produced improvement in a high compression engine . I have witnessed awesome power numbers in pure alcohol race engines but that's a different beast !

 

[North by Northwest]

https://parkerhomestore.com/?produc...-duraforce-engine-oil-w-stabilizer-8-oz-89930
I'm confused.

Mr Walker , means low ash is problematic ! Ashless is what is recommended in all lawnboy engines , just at different fuel to oil mix ratio's as the engine technology & design became more refined .

 

[North by Northwest]

Don't kid yourself. Your English is pretty good.
Knocking is most often used to describe pre ignition. Detonation often can't be felt or if it can it feels like a small misfire or loss of power.
I had an engine equipped with EGT gages and a data logger. It entered into a detonation event so severe it melted the piston past the second ring and painted the entire exhaust with molten aluminum. The data logger never picked it up. The engine was running great until it wasnt!

Exactly correct !

 

[North by Northwest]

Most of my expiereance has been with Duraforce motors. I've had three of them and two snowblower with the same basic engine in piston port format.
I'll post some piston pics tonight.

P.S. sorry for the typo on the M-Series oil data , 64:1 was the manufactures design set point on the injection system . Otherwise 40:1 in Premix . I had to go Premix for a few yrs with my 1st M-series when the oil injector crapped out after 15 yrs , which necessitated the Opti2 Premix @ 50:1 trial . I eventually replaced the injector pump but it again failed on both mowers after 20 yrs and I just when with premix on both and they still are running fine today . P.S.S. Mr Walker do send the pics of your newer Duraforce when time permits , I had the last manufacturers Duraforce model yr & a Toro clone after that . My son still has the Toro at his camp loves it .

 

[Joisey]

Mr Walker , means low ash is problematic ! Ashless is what is recommended in all lawnboy engines , just at different fuel to oil mix ratio's as the engine technology & design became more refined .

OK, now I understand.

 

[bwalker]

P.S. sorry for the typo on the M-Series oil data , 64:1 was the manufactures design set point on the injection system . Otherwise 40:1 in Premix . I had to go Premix for a few yrs with my 1st M-series when the oil injector crapped out after 15 yrs , which necessitated the Opti2 Premix @ 50:1 trial . I eventually replaced the injector pump but it again failed on both mowers after 20 yrs and I just when with premix on both and they still are running fine today . P.S.S. Mr Walker do send the pics of your newer Duraforce when time permits , I had the last manufacturers Duraforce model yr & a Toro clone after that . My son still has the Toro at his camp loves it .

Here is a duraforce ran its entire life on quality low ash Jaso FC and FD oils. Notice the piston crown is covered in mettalic deposits and the deposits actually extended down from the crown and into the ring grooves. This was my first Duraforce that I bought back around 1998 IIRC.I tore this one down around 2005 due to lack of compression. Both rings where stuck in the grooves., but no damage or scoring noted. Spark plug life is short with low ash oils in these engines as well and all that mettalic buildup contributes to burning up the coils as well.