Fuel Oil Ratio

[eyolf]

I have resisted the urge to put in my 2/1,000,000 of a cent worth because there are some pretty wise gleanings on this thread. I had hoped somebody would address the octane thing, though, so I will chime in.

I do not know about everybody's gas, but in my area, all of the regular, most of the midgrade and some of the premium has ethanol in it. Other areas have MBTE in their gas, which behaves a lot like methanol in that it attracts water.

But, at least a few stations have a pump that carries a label designating the gas to be "for antique or special interest vehicles, or off-highway equipment, contains no oxygenated additives." Legally, the stuff is not to be used in your daily driver, but that's OK, it costs enough more that most people won't anyway. This gas is always premium, at either 92 or 93 (r+m/2) octane here.

I'm not certain if I need the octane or not, but I can mix up gas and have it last for 3 or 4 months with no deterioration in the winter, and 6-8 weeks in the summer. Use the 87 gas, and it starts to reek in a couple of weeks. A side benefit: fewer carb rebuilds with the expenssive gas. I think it's worth the extra 20 cents or so.

Having said this, I admit that I don't know what the situation is in most other places. Maybe it only comes to pass in the upper midwest.

As far as oil ratio goes, I have been able to succesfully use 50:1 in almost everything I own, Saw wrenches know...often when we tear a two-stroke down, we find a little oil in the crankcase, bearings, etc. coating everything in a thin layer. This is oil that has separted out of the fuel mix, not gotten burned. Even at 50:1, we are leaving some oil in the crankcase. You can often run a two stroke on straight gas for several minutes before wrecking it...it takes a little while to wash all the old oil away.

I think this supports the premise that 50:1 ratios are fine for any modern two-stroke engine in reasonably good repair.

 

[Dagger]

Whew!..ok..
Methoss..Easy..I recommend whatever the design team that cooked up the engine does!..they did the inital testing..made sure it fell within the parameters of their goals. If you think they made a mistake...then do the heat monitoring test!
NOW..im really gonna stir everyone up..but.. the "color" on the plug is a dang poor way to judge cylinder head temp..it gives you an approximation only of flame/combustion temps..not cooling effectivness. This is only accomplished with thermocouples and temp monitoring equip.

sawracer...Blue rods, heat yes...but why..you have to find that.
High rpm rod ends are difficult to engineer good flow to the bearings, with small crankcase areas to achieve and lowering the mass of internal recprocating parts to help achieve those rpm,s AND keep the weight down due to SALES requirements, these "lighter" weight components transfer heat from the piston down the rod much easier than the old days..and dont cool as easily..the scallops are an obvious way to attempt better flow..you said "lately"...hmmm hard to know what you mean..are the saws newly manufactured?..3 to 5 years old..or just all the saws from all eras lately?...got fuel problems in your area?..how many gasoline distributers supply the stations in your area?.. your question just brings more questions..but first...WHY the HEAT...
AND...big end needle bearings "skate" from excessive clearance...then hammer apart usually.

Big Cicero. ..Specifically,, the "burn" is not hotter.
The cooling effect of the mix is reduced..resulting in a "hotter" temp piston...yes, there are more BTU's in oil that gas...but the burn rate is so slow that it never burns in the combustion chamber..just kinda cooks and spitsout carbon and "paints the skirt with that brown color you all have seen..thats because the piston is getting so hot...plus oil as 100 times the "unburnable" impurities than gas.. an so on.. so you distributer service rep just didnt chose his words carefully!

Keener..smart fella...you obviously dont consider yourself a better engineer than the design team that cooked up your dream machines...stick with it pard!

Eyolf....I run 92 or 93 for the same reason at home in my personal stuff for the same reason...dont need the octane, in fact I know its actually a detriment in all but my highest performance(read that highest compression ratio's) equip...but it lasts MUCH longer than the 87 cheap stuff..


"If you think you have a good high performance piece of equipment, and you like it..then you credit the design team that worked up the model...if you think they were so smart as to accomplish this feat of high performance engineering, but lost all their knowledge when recommending lubrication specs, you have give them no credit at all!

 

[Fish]

Dagger.
I thought you said you were on the design team.
Your first post had a lot of "we" references, but
your last post stepped away from that a little.
Without specifics, do you work for a company
that makes chainsaws? Just curious. Any Llamas
up your way?

 

[Dagger]

heeh Llamas...

Well as the matter of fact..Llamas are begining to show up round here!!...lots of Midwest farmers raising 'em...but I got a kick out of that comment Fish...I read ya...probably well deserved to pard!


The words "we" were chosen simply to designate the brotherhood that i guess all engineers share, and I did not mean to imply that I personally was on all the design teams of all these advances..certainly not.. only some.

I think if I had to describe myself honestly, I would not use titles, degrees or sheepskins...but I'm simply an all-american boy (at the half century mark)..that is a gear-head, tinkerer, sportsman, salesman, pilot ,with a wrench for a heart!..oh ya and I forgot Lucky!..because I have been able to make a good career in an area that I enjoy...POWER!
I spend my spare time at home makin chips' too!.. not many wood chips, ..but metal...in my home shop I have 2 lathes, a vertical mill, valve grinding , dyno,and all sorts of machine shop equip, currently working on a radial aircraft engine design for light planes!..(Read that DREAM MACHINE)

What I am NOT is a journalist, and my grammer ..or choice of words certainly shows that!..
I am an Engineer however..specifically it says on my diploma an aeronautical engineer..but I cant really claim any employment expierience in that field, only as a hobbist, graduating from college in the early 70's . My employment expierience in the engineering field is with power equipment.

I have been deeply involved in the field of chainsaw/outdoor power equipment for..hmmm..exactly 22 years last summer..WHEW!
Without reading you my resume, since i am not looking for a job, (kinda hope to retire at the one I have, I like it here), I will simply tell you that I have previously worked for a couple of the major power equip manufacturers that you know of, and currently do still. Spent time in a certain scandinavian country on project development..in the late 80's (engineering team), went back on a sales project a couple a years later (sales team) and left that company later on due to mainly philosophical dissagreements.
(read that HONOR)
and have spent quite alot of time in the sales end of this biz in this country, from the top end of the supply line...to the bottom, and have had affiliations with 3 major chainsaw/outdoorpower equip manufacturers.
Still wish I had studied my grammer more, and learned to type better..!

I have not been a member of this board very long, and I certainly enjoy reading the threads, because as Keener said, "It causes me to think about what I thought I knew",

and have also learned that a fella ought to read his over a couple a times before he posts 'em too!

Everything I know could be wrong!


"Nothing more fullfilling than excersizes of the mind"

 

[Fish]

Don't mind me. I am just an impish troublemaker
that enjoys harrassing everyone here. I was
just curious if you were actually in the biz or not,
not trying to take you to task on semantics. I hope you
stick around so you can keep us on our toes. Since you are
in the biz, I don't need to know where, then you must
post responses on some of these other posts involving
laminar flow, etc. I won't let you just dominate the oil/mix
topic. You will put a huge damper on the folks here that
like to use big words though, as it is not much fun arguing
with someone that knows everything. I have a lot of
family and ex-brother-in-laws that are engineers, as
well a lot of professors that are drinking buddies, so
I love giving them hell, you must forgive me. I was not
trying to get you to reveal your place of employment and have
no desire to jeopardize your position. Since you revealed a little
about your past, I wonder if you know Walt. Hence my Llama
reference.
Since my dad was an engineer I feel compelled to call you uncle
dagger.
This forum has a lot of good people, a few not so good. But
we all enjoy the discussion. Keep posting here, and do not
get mad at my harrassments, as everyone here will testify,
I do it to everyone.

 

[Methoss084]

Sorry if I sounded a bit pushy, not the intended mood or mode. Dagger, I only stated the grey plug as a "Oh no its to Late!" reference. But since we are on the subject of 2 cycle oil. What are everyones feelings on Synthetic base 2 cycle oils? Pros and Cons.

Thanks Josh.

 

[kdhotsaw]

Scaring the hell out of dagger!

Hello dagger,
This post you wrote on 50-1 to 100-1 is just not correct. no engine manufacturer that builds 2-stroke engines or makes high quality 2-stroke engine oils recommend the
50-1 oil ratio,s. if you have a 250 motorcycle that doesn't operate over 7000 rpm maxima says you can use 50-1 if its synthetic oil. if you go to a 125cc motor and it turns over 10,000 they recommend 25-1 80cc engine that turns over10,000 they recommend 20-1. on yahama's kts-100 kart they recommend 15-1 on petroleum based oil and 25-1 with synthetic oil.In europe on the grand prix karts they are turning 22,000 rpm and making over 40 hp on the 125 shifter karts and they are using 100 percent synthetic at 12.5 to 15- 1 oil ratio's. They do this because their engines wont last at 40-1 or 50-1. they all tried the 100-1 and 50-1 when this was the craze 20 years ago but it didnt work .
the biggest reason you get varnish on a two stroke motor is because with a petroleum based oil . once you reach the 400 degree tempeture on the piston and cylinder wall it begans to break down and turn to a solid and becomes a varnish. Maxima 929 synthetic can be taken to 770 degrees before breakdown of the oil.
when you go on and on about 50-1 and 100-1 ratio's. you sound just like all the stihl factory instructors and factory reps i have ever talked to about oil. Isn't it strange that only the chainsaw, leafblower and weed wacker mfg's are hawking 50-1 ratio's. THey went over to 50-1 when the epa put in their emmision controls on thier motors. they pull engines right off the assembly line randomly and test them for emmisions. when they went to 50-1 is also the point in time that stihl started started having piston seisures on the 066's and husky started having big end rod failures
Sawracer works at a stihl-husky dealership here in california, they had a account that cut brush for PGE . they would buy ten saws at a time. first they lost almost all the big end bearings on the372 husky rods, then they bought 044 and 046 stihls and had piston/ barrels seisures. they finally went to 32-1 oil ratio and the problems were gone. I Dont Know of any engine builders and very few loggers that use 50-1. when You engineering guys design a motor or run all these tests then you need to go out to the dealers and see how this stuff works and what kind of problems are out there. talk to the mechanics, they give you the good data. of course that wont work on the oil ratio problem because stihl and husky are locked in to 50-1 because of the epa here in the usa
.
Ken kdhotsaw

 

[WOLF_RIVER_MIKE]

Maxima 929

Where can you purchase Maxima 929?

 

[tony marks]

sometimes the forum offers an opportunity to read in terms we can understand ,info that we would probably never have the opportunity to get otherwise.seems to me this would help the
good mechanics as well as the users . dont mean i accept everything i read but i do read it an appreciate an respect the offer of
knowlege gained by those offering the help.later now

 

[dbabcock]

Mike,
I think that was a typo. That's Maxima 927. I got mine mailorder in about 5 days UPS ground from Troy Racing in CA (1-800-755-2112). I got 2-64 ounce containers at $16.95 ea. Shipping for this amount was about $9.00. They do sell 16 ounce containers, but at $5.95 each, they're more expensive.

 

[seesaw]

confused on which quote is who's?

KD,
your post states "no engine manufacturer that builds 2-stroke engines or makes high quality 2-stroke engine oils recommend the 50-1 oil ratio,s."

are these your words? Curious because your post goes on the state...

"Isn't it strange that only the chainsaw, leafblower and weed wacker mfg's are hawking 50-1 ratio's."

Surely the later is true. alot of 2-stroke mfg's recommend 50-1. There are plenty of mfg's that produce "high quality engine oils" that offer a wide variety of mixture ratios right on their bottles?

I'm really not trying to stir up any mischief (Fish) but, I find this thread very interesting and want to understand each fella's points. It really is a great place to learn because you guys have tremendous amounts of experience and knowledge to share. Thanks for that!
(Sorry for quoting the entire post earlier...I'm a rookie, it was an accident).

 

[thacket]

Tolerances

Hi All,

I have what might be some dumb questions. Did chainsaw manufacturers change their engine tolerances to accomodate the change to higher oil/fuel ratios? Does anyone know for sure? Some of you have noted more engine failures after the change. Does this still continue?

John

 

[Fish]

I was wondering how you typed with such big letters.
I just assumed that you had really big fingers.
I find this thread interesting as well. I just have
seen no piston/cylinder damage that could be
attributed to using 32:1 ratio.
Piston damage on saws around here usually are:
Carbon buildup causing
actual scratching yes. Seizures from
running too lean on air/fuel mix, yes. Seizures from
insufficient oil, yes. The scoring pattern is different from
lean seizures.
Bad fuel and dirt entry cause most of the dirt/gum/scum
around here but no seizing. wear yes. Of course this is
little saw country. Big saws, and hotsaws, I cannot
comment on. No piston melting or preignition due to
regular gas either. These things may be regional, but
not around here. An 036 is considered a real big saw
here. I always use 32:1 with good results.
We had an earlier thread about whether or not the
manufacturers sought out the input/advice from
homeowners or mechanics in the field. Specifically
do engineers seek out this input? I contended that
the answer is no, they do not. Distributor/sales reps
may pretend to jot down something and say they will
get right on it but that is about the extent. The thought
of any of this info ever reaching the manufacturer's
engineering dept. is absurd. If it did it would be
promptly hit the trash can.
I am not trying to stir any trouble, just calling it
as I see it. If I am off the mark anywhere, let me know
{I know you all will}.

 

[WOLF_RIVER_MIKE]

I got mine mailorder... from Troy Racing...

Thanks Doug

 

[confused]

Hey Doug,

Is the Maxima 927 that great? I'm using the Stihl oil I received with my saw (good dealer), however, I am almost out. Is this the stuff Ken D. recommended for your 3120?

Thanks

 

[dbabcock]

Confused,

I think the principle behind the synthetic and castorbean blend is good for Maxima. Ken explained it to me over the course of a half a hour or so on the phone last week, so on his reccomendation I bought it. If Ken says to get it, I know he backs it up with experience. I'll use it in all my saws from now on.

 

[Bruce Selfridge]

Don't argue with Ken it's like arguing with Art over chains their product and knowledge speeks for themselves. My vote 32:1.

 

[Dagger]

Well Ken, I guess we can just agree to disaree pard!
Funny thing is, you have so many good facts in your post that I completely agree with.
Aint it funny how 2 fellas can stand on different banks of the creek and see the same water so differently!
I guess I either didnt make my lube vs. cooling very clear, or you don't believe it.
I ask you to consider all the engine types you mentioned, and examine the different cylinder/skirt clearance design specs, and also the cooling effiecency of each engine.
Can we agree that the larger a bore size, the larger the clearance can be before piston stabilization is effected? Also can we agree on the faster the piston speed (function of stroke and RPM in FPS) the closer the tolerance needed to maintain piston stabilization without adding more rings?..in other words a 15,000 rpm short stroke engine can have a slower piston speed (FPS) than a 10,000 rpm long stroke engine. I think we surely can come together here. If we ponder these things I think we might see that not all of the examples given compare to the saw engines that concern us. I dont know for sure. If you already know that the examples you mentioned have similiar piston speeds, and similiar cooling effiencies, then you are ahead of me, which is certainly possible!

Now, I could be wrong..but I surely believe that the very rich oil ratio's used in the racing engines you have named are due to the fact they have discovered that you can raise the *BMEP (lets call it combustion pressure) with all that unburned non-compressable oil in the combustion chamber,and raising the power just like water injection does. But they certainly dont have to meet a 300 to 400 hour durability design goal! therefore the detrimental effect of higher carbon build-up due to extra oil does not concern them. (did ya read that Fish?) Just as long as the cooling effeciency is up to the reduced cooling effect of the fuel mix on the engine.

Which brings me to the Synthetic oil. I have noticed in posts that you recommend the Maxima synthetic mix oil, which I have no expierience with, But I have no doubt that this is GOOD advice to most all users, as the higher heat capabilities of synthetics is a definate asset, not to mention better lubrication qualities. In fact, in the days before Nicasil, we were actually exploring the insulative effects of some synthetics to help keep cylinder heat from transferring to the pistons! We were chasing those RPM's vs durability problems..we needed closer tolerances between skirt/wall to maintain piston stabilization at a higher RPM goal, and due to a thinner oil film, heat transfer was a real problem ! of course , Nicasil came along and changed our direction.

You have such a good point when you say that we should design a saw and then go out and talk to the mechanics in the feild..well I cant vouch for all companies..but I WAS THERE when the 3120 was released to 1 distributor in the west and for 6 months shipments would not be released to anyone else untill data collected in what we then called a "test market" to see if there were gonna be any shortcomings in the new design..there were, and they were corrected in production ASAP!..However I will also admit that after the test market period, the chance of a dealer telling his sales rep of a problem and then it getting back to the appropriate ears is very low! After the test market period the failure analysis data is collected solely by computer on warranty claim info! It then goes to the accounting dept and if they think its costing to much...then engineering will get a call!
That was along time ago however, and alot of things have changed with that company, dont think they do that anyore.

It's probably not a big deal, but your timeline is incorrect Ken on when 50:1 was adopted..it was way before then, and the 044 and O66 were probably not even a design spec yet. 266SE had just come out and the EPA was not even looking at the chainsaw world. I assure you my friend, emissions regs had nothing to do with the change. Stihl and Husky are not "locked in" to 50:1 because of EPA regs. NOx content is what we are striving to reduce by EPA mandate, and that is effected very little by the oil ratio.

Here..lemme really get ya going on gov regs, In Scandanivia, it is well known that when you are logging in the winter in the deep snow and you must dig down far to the base of a tree, the sawyer ends up in a hole with all those exhaust fumes that cant get away from him..bad deal right! He can be overcome by the carbon monoxide very quickly. They developed a vegetable based mix based on canola oil that will not overcome the user..cool...
When a distributor in the USA discovered this..he thought it would be a great tool to market as enviromentally friendly! He obtained a part number somehow, as it was never published in the US books...and ordered just 3 cases. When the shipment arrived at Port of Entry the manfest was of course inspected by customs and then, upon reading of this canola oil in the container without an FDA approval number on the manifest..the entire container was Impounded. Customs held this container for 6 weeks. It was only until a representative from sweden flew in (I picked him up at the airport) and relieved the container of the contraband..thats what they called it, and was escorted by a customs agent back to the airport and on the plane would they release the container! this has been 15 years ago probably.
Now you tell me, if the EPA really wanted clean burning saws, why wont they ask the FDA to approve this canola oil based mix as an alternative to petroleum based mix..Husqvarna tried to get this done for several years, and our gov would not allow it! I dont know if they ever did get it approved.

 

[Harley]

Couple of things.

Dagger, what temp difference are we talking about? 10 or 20 degrees? Or more? I don't have a termocouple on hand, please enlighten me. Also the fact that the temp rises as a result of more oil in the mix, means that the Nox level would be higher. Supporting the idea that the higher ( numerical ) ratios improve emissions.

I switched from 50:1 to 40:1 a few weeks ago, after reading some things that Ken wrote. I examined the piston before and after. I did adjust the carb. My engine is alot cleaner now. The piston looks like its brand new, and there's less carbon on the top of the piston. No signs of oil varnish on the skirt. It's a new Stihl, somewhere around 20 cords on it. I use Stihl mix and high octane Exxon.

I want to try the Maxima, but I have some Stihl oil left over. No modified saws, yet. But when I get one I'll switch yet again to 32:1.

 

[Dagger]

Harley..will be different for different saws of course..but I Used to demonstrate this to dealers in the feild with a 3 cube open ported saw..and would get around 30 degrees or so..and then with a 4 cube closed port pro saw and get around 40 degrees , when it was really cold outside, temp difs were slightly lower..maybe 4 or 5 degrees...didnt notice that right off because the same saws were always having the high speed needle adjusted so I chalked the differences up to that initially...but after awhile ..it became apparant that outside air temp did effect it slightly.
Then I would really scare em and put the thermocouple on the exhast bolt!...turn the high speed adjustment in an out and the digital temp moniter would go up an down like a laggy speedometer, at 3 times the temp too!
now..I know some of you might think...30 or 40 degrees..so what!..but the difference between 400 and 440 degrees under the spark plug is the diff between meltin down the piston or not.

the carbs is NOT adjusted between switching mix.
and also.. the feild test is done simply to prove the gas with less oil content cools better than gas with more.

most of you understand this I know...but for those who are having a hard time picturing it..stick your hand in a can of gas that is room temp and when you bring it out...your hand gets cold...stick your hand in oil the same temp and when you bring it out...nothing. thats the evaporitive cooling effect of gasoline..same deal on the piston underside.

Now lab testing is quite a bit more involved...but the system is the same...for a new design , the team will have heat monitoring devices in several places, and run the saw on a load inducing machine for long periods of time.